LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 LM25056 System Power Measurement IC with PMBus Check for Samples: LM25056 FEATURES APPLICATIONS * Input Voltage Range: 3V to 17V * I2C/SMBus Interface with PMBus Compliant Command Structure * Remote Temperature Sensing with Programmable Warning and Shutdown Thresholds * Real Time Monitoring of VIN, IIN, PIN, VAUX with 12-bit Resolution and 1 kHz Sampling Rate * True Input Power Measurement Using Simultaneous Sampling of VIN and IIN Accurately Averages Dynamic Power Readings * Averaging of VIN, IIN, PIN, and VAUX Over Programmable Interval Ranging from 0.001 to 4 Seconds * User Programmable WARN and FAULT Thresholds with SMBA Notification * Black Box Capture of Telemetry Measurements and Device Status Triggered by WARN and FAULT Conditions * Full Featured Application Development Software * WQFN-24 Package * * * 1 234 Server Backplane Systems Base Station Power Distribution Systems Subsystem Power Measurement DESCRIPTION The LM25056 combines high performance analog and digital technology with a PMBusTM compliant SMBusTM/I2C interface to accurately measure the operating conditions of electrical systems including computing and storage blades connected to a backplane power bus. The LM25056 continuously supplies real-time power, voltage, current, and temperature data to the system management host via the SMBus interface. The LM25056 monitoring block captures both realtime and average values of subsystem operating parameters (VIN, IIN, PIN, VAUX) as well as peak power. Accurate power measurement is accomplished by measuring the product of the input voltage and current through a shunt resistor. LM25056 current measurement has a 1.5% accuracy over the temperature range of -40C to +85C with operation from -40C to +125C. A black box (Telemetry/Fault Snapshot) function captures and stores telemetry data and device status in the event of a warning or a fault. Typical Application Schematic RS +12V MMBT3904 VIN VOUT POL REGULATOR CIN VIN VDD VS+ VS- DIODE ADR2 NC ADR1 NC ADR0 VAUX VREF ENABLE LM25056 SMBA SMBus Interface CVREF VDD SDA CVDD SCL DGND AGND 1 2 3 4 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. SMBus is a trademark of Intel Corporation. PMBus is a trademark of SMIF, Incorporated. All other trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2012-2013, Texas Instruments Incorporated LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com VAUX NC NC NC AGND NC DGND Connection Diagram SDA ENABLE SCL VIN SMBA NC NC NC VS- VDD DIODE ADR0 VS+ ADR1 VREF ADR2 24 NC Exposed Pad 1 Solder exposed pad to ground. Figure 1. Top View WQFN-24 2 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 PIN DESCRIPTIONS Pin No. Name Description Applications Information PAD Exposed Pad Exposed pad of WQFN package No internal electrical connections. Solder to the ground plane to reduce thermal resistance. 1 ADR2 SMBus address line 2 3 - state address line. Should be connected to GND, VDD, or left floating. 2 ADR1 SMBus address line 1 3 - state address line. Should be connected to GND, VDD, or left floating. 3 ADR0 SMBus address line 0 3 - state address line. Should be connected to GND, VDD, or left floating. 4 VDD Internal sub-regulator output Internally sub-regulated 3.7V bias supply. Connect a 1 F capacitor on this pin to ground for bypassing. VDD can be driven from an external voltage for low voltage operation. 5 NC No Connect Not bonded to die. Can be connected to the ground plane. 6 NC No Connect Not bonded to die. Can be connected to the ground plane. 7 NC No Connect Not bonded to die. Can be connected to the ground plane. 8 VS- Current sense input (-) Negative IIN sense amplifer input. The voltage across the current sense resistor (RS) is measured from VS+ to this pin. 9 VS+ Current sense input (+) Positive IIN sense amplifier input. The voltage across the current sense resistor (RS) is measured from this pin to VS-. 10 NC No Connect 11 VIN Positive supply input Not bonded to die. Can be connected to the ground plane. 12 ENABLE Enable 13 VAUX Auxiliary voltage input 14 NC No Connect Not bonded to die. Can be connected to the ground plane. 15 NC No Connect Not bonded to die. Can be connected to the ground plane. 16 NC No Connect Not bonded to die. Can be connected to the ground plane. 17 AGND Analog ground 18 NC No Connect 19 DGND Digital ground 20 SDA SMBus data pin Data pin for SMBus. 21 SCL SMBus clock Clock pin for SMBus. 22 SMBA SMBus alert line Alert pin for SMBus. Active low. 23 VREF Internal reference Internally generated precision 2.82V reference used for analog to digital conversion. Connect a 1 F ceramic capacitor on this pin to ground for bypassing. 24 DIODE External diode A small 0.1 F ceramic bypass capacitor close to this pin is recommended. VIN is measured from this pin. Enable pin. This pin has a rising threshold of +1.2V to enable the LM25056. Lowering this pin below the 75mV hysteresis from the +1.2V threshold will put the part into power down mode. Auxiliary pin allows voltage telemetry from an external source. Full scale input of 1.2V Connect analog ground to digital ground and then to a quiet system ground. Be sure to avoid high current return ground lines. Not bonded to die. Can be connected to the ground plane. Connect analog ground to digital ground and then to a clean system ground. Be sure to avoid high current return ground lines. Connect this to a diode-configured MMBT3904 NPN transistor for temperature monitoring. These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) VIN, VS-, VS+ to AGND/DGND -0.3V to 24V SCL, SDA, SMBA, ADR0, ADR1, ADR2, VDD, VAUX, DIODE, ENABLE to AGND/DGND -0.3V to 6V VS+ to VSESD Rating (3) -0.3V to +0.3V Human Body Model 2kV Storage Temperature -65C to +150C Junction Temperature +150C (1) (2) (3) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional. For specifications and conditions see the Electrical Characteristics. If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications. The human body model is a 100 pF capacitor discharged through a 1.5 k resistor into each pin. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 3 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Operating Ratings VIN, VS-, VS+ voltage 3V to 17V VDD 3V to 5.5V Junction Temperature -40C to +125C Electrical Characteristics Limits in standard type are for TJ = +25C only; limits in boldface type apply over the junction temperature (TJ) range of -40C to +85C unless otherwise stated. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25C, and are provided for reference purposes only. Unless otherwise stated the following conditions apply: VIN = 12V. See (1) and (2). Symbol Parameter Conditions Min. Typ. Max. Units Input (VIN Pin) ISUPPLY-EN Supply current, enabled ENABLE > 1.2V 1.7 2.8 mA ISUPPLY-DIS Supply current, disabled ENABLE < 1.2V 10 100 A VREF Reference VREF Reference voltage 2.82 V VDD Regulator (VDD pin) VDD IVDDLIM 3.1 3.7 4.1 V VDD current limit VIN = 12V 50 mA PORVDD Power on reset threshold at VDD VDD increasing 2.4 PORHYS POR hysteresis VDD decreasing 90 mV 12 Bits Acquisition round robin time Update all telemetry channels 1 ms 3.0 V ADC and MUX Resolution tRR Telemetry Accuracy 20 A IINFSR IINIB Current sense input bias current Current sense full scale range, VSENSE = GAIN = 0 VS+ - VSGAIN = 1 29.68 mV 60.88 mV IINLSB Current sense input LSB GAIN = 0 7.25 V GAIN = 1 14.87 V 1.199 V VAUXFSR VAUX input full scale range (ADC native range) VAUXLSB VAUX input LSB 293 V V 6.14 mV Supply voltage measurement full scale range VINLSB Supply voltage measurement LSB IINERR Current sense measurement error GAIN = 0, VSENSE = 25 mV IINERR Current sense measurement error GAIN = 1, VSENSE = 55 mV PERR Input power measurement error GAIN = 0, VIN = 12V, VSENSE = 25 mV PERR Input power measurement error GAIN = 1, VIN = 12V, VSENSE = 55 mV VINERR Input voltage measurement error VIN = 12V -1.5 +1.5 % Auxiliary measurement error VAUX = 1V -2.5 +2.5 % VAUXERR For calculation only, observe maximum voltage ratings. 25.13 VINFSR -1.5 +1.5 1 -3 % % +3 2 % % Remote Diode Temperature Sensor TACC IDIODE (1) (2) 4 Temperature accuracy using local diode 3 C Remote diode resolution 9 bits External diode current source High Level 240 Low Level 9.2 325 A A Current out of a pin is indicated as a negative value. All electrical characteristics having room temperature limits are tested during production at TA = +25C. All bold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Electrical Characteristics (continued) Limits in standard type are for TJ = +25C only; limits in boldface type apply over the junction temperature (TJ) range of -40C to +85C unless otherwise stated. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25C, and are provided for reference purposes only. Unless otherwise stated the following conditions apply: VIN = 12V. See (1) and (2). Symbol Parameter Conditions Min. Diode Current Ratio Typ. Max. Units 26 PMBus Pin Thresholds (SMBA, SDA, SCL) VIL Data, clock input low voltage VIH Data, clock input high voltage VOL Data output low voltage IPULLUP = 5 mA ILEAK Input leakage current SDA, SMBA, SCL = 5.5V ENABLE threshold voltage Rising threshold 0.9 V 2.1 5.5 V 0 0.4 V 1 A ENABLE Pin VEN VEN-HYS ILEAK IPULLUP ENABLE threshold voltage hysteresis Input Leakage Current 1.4 1.2 V 75 mV ENABLE = 5V ENABLE pin pullup current 1 2.8 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 mA A 5 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics Unless otherwise specified the following conditions apply: TJ = +25C, VIN = 12V. All graphs show junction temperature. VIN Pin Current (Enabled) VIN Pin Current (Disabled) 1.8 14 17V 5V, 12V, 17V 12 CURRENT ( A) CURRENT (mA) 1.7 1.6 1.5 1.4 10 12V 8 5V 6 1.3 1.2 -40 -20 3V 3V 4 0 20 40 60 80 100 120 140 TEMPERATURE (C) -40 -20 Figure 2. 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 3. VS+ Pin Input Bias Current (Enabled) VS- Pin Input Bias Current (Enabled) 12 25 CURRENT ( A) CURRENT ( A) 24 11 10 23 22 21 9 20 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) -40 -20 Figure 4. 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 5. POR Threshold ENABLE Threshold 2.50 1.30 2.46 1.25 VOLTAGE (V) VOLTAGE (V) Rising 2.40 2.35 2.30 Falling Rising 1.20 1.15 2.25 2.20 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Falling 1.10 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 6. 6 Figure 7. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Typical Performance Characteristics (continued) Unless otherwise specified the following conditions apply: TJ = +25C, VIN = 12V. All graphs show junction temperature. VREF Voltage VDD Voltage 2.840 3.73 2.835 3.72 VOLTAGE (V) VOLTAGE (V) 2.830 2.825 2.820 2.815 3.71 3.70 3.69 2.810 3.68 2.805 2.800 3.67 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 8. Figure 9. VIN Error, VIN=12V VAUX Error, VAUX=1V 1.0 1.0 0.8 0.8 VAUX ERROR (%) VIN ERROR (%) 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 0.6 0.4 0.2 0.0 -0.2 -0.8 -0.4 -1.0 -0.6 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 10. Figure 11. IIN Error, GAIN=0, VSENSE=25mV PIN Error, GAIN=0, VIN=12V, VSENSE=25mV 0.4 0.8 0.6 0.4 PIN ERROR (%) IIN ERROR (%) 0.2 0.0 -0.2 -0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -0.6 -1.0 -0.8 -1.2 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 12. -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 13. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 7 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified the following conditions apply: TJ = +25C, VIN = 12V. All graphs show junction temperature. PIN Error, GAIN=1, VIN=12V, VSENSE=55mV 0.8 0.3 0.6 0.2 0.4 0.1 0.2 PIN ERROR (%) IIN ERROR (%) IIN Error, GAIN=1, VSENSE=55mV 0.4 0.0 -0.1 -0.2 -0.3 0.0 -0.2 -0.4 -0.6 -0.4 -0.8 -0.5 -1.0 -0.6 -1.2 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 14. 8 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 15. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 VS- VS+ VIN VDD 3.7V Block Diagram VDD REG VREF 2.82V 1.2V 2.35x REF GEN BUF 1/21 12 bit ADC S/H AMUX 20x, GAIN=0 40x, GAIN=1 ENABLE Black Box SMBA SMBus Interface Telemetry State Machine SDA VAUX Measurement/ Averaging Warning Registers ADR0 ADR2 DGND ADR1 Address Decoder Diode Temp Sense AGND DIODE SCL FUNCTIONAL DESCRIPTION The LM25056 provides intelligent monitoring of the input voltage, input current, input power, temperature, and an auxiliary input. The LM25056 also provides a peak capture of the input power and programmable hardware averaging of the input voltage, current, power, temperature, and the auxiliary voltage. Warning thresholds which trigger the SMBA pin may be programmed for input and auxiliary voltage, current, power, and temperature via the PMBus interface. Enabling/Disabling and Resetting The LM25056 has an ENABLE pin that can be used to power on and off the device. If desired, the LM25056 can be kept in shutdown until the supply reaches a particular threshold using ENABLE with a resistor divider or with an active control as shown in Figure 16. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 9 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com +12V VIN ENABLE LM25056 SHUTDOWN CONTROL GND Figure 16. ENABLE Control When taken low, this logic pin will reduce the quiescent current for the device and will no longer respond to PMBus commands. Also, taking the ENABLE low is a functional reset of the LM25056. Raising ENABLE sets the part to its default operation. If this functionality is not used, then ENABLE should be left floating (an internal pullup will maintain its operation) or tied to an external VDD voltage. Do not tie ENABLE to the onboard VDD. The VDD power-up is delayed and when power is first applied, and VDD starts low. This in turn will keep ENABLE low and the LM25056 will not start up. VDD and VREF also have a power-on-reset (POR) circuit that holds the LM25056 in reset until it reaches the operating state. Note that if either of these output lines are inadvertently pulled low, the device is reset to its initial default state, erasing the volatile memory the same as ENABLE pulled low. Once VDD and VREF have reached the POR threshold of 2.4V, the device comes out of reset. As an example, the SMBus address of the LM25056 is captured based on the states (GND, NC, VDD) of the ADR0, ADR1, and ADR2 pins during turn on and is latched into a volatile register once the ENABLE pin is determined to be high and the VDD and VREF has exceeded its POR threshold of 2.4V. Reassigning or postponing the address capture can be accomplished by holding the ENABLE pin to AGND. For more information on the operation of these pins, please see the PMBus Address Lines section of this datasheet. The logic and volatile memory can also be reset with a PMBus write to the MFR_DEVICE_SETUP (D9h) register into the software reset bit. However, this software reset will not trigger a read of the states of the address pins as the ENABLE pin or VDD and VREF POR events will. VDD Sub-Regulator The LM25056 contains an internal linear sub-regulator which steps down the input voltage to generate a 3.7V rail used for powering low voltage and low power circuitry. When the input voltage is below 3.7V, VDD will track VIN. For input voltages 3.3V and below, VDD should be tied directly to VIN to avoid the dropout of the sub-regulator. The VDD sub-regulator should be used as the pull-up supply for the ADR2, ADR1, and ADR0 pins if they are to be tied high. It may also be used as the pull-up supply for SMBus signals (SDA, SCL, SMBA). The VDD subregulator is not designed to drive high currents and should not be loaded to drive high current circuits. The VDD pin is current limited to 50 mA in order to protect the LM25056 in the event of a short. The sub-regulator requires a ceramic bypass capacitance of 1 F or greater to be placed as close to VDD as the PCB layout allows. Additionally, VDD can be driven from an external source to maintain telemetry readings for VIN and temperature if the VIN drops below its operation point. To do this, use an external 5V supply driving the VDD through a Schottky diode. This allows for telemetry readings down to VIN=0. A large capacitor (100uF) can also be placed at on the VDD line to momentarily supply current to the device to similarly maintain telemetry readings that would normally shutdown and reset the device. Note that when using an external VDD drive, ENABLE will not operate independently. To use this functionality, simply connect the external VDD source to ENABLE and lower this source to put the LM25056A into low power mode. 10 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Remote Temperature Sensing The LM25056 is designed to measure temperature remotely using an MMBT3904 NPN transistor. The base and collector of the MMBT3904 should be connected to the DIODE pin and the emitter of the MMBT3904 connected to AGND. Place the MMBT3904 near the device whose temperature is to be monitored. In noisy environments with large currents or switching noise, it is especially important to bring this connection back to AGND and not just to the nearest ground plane. If the temperature of a pass MOSFET is to be measured, the MMBT3904 should be placed as close to device as the layout allows. The temperature is measured by means of a change in an external diode voltage in response to a step in current supplied by DIODE. DIODE sources 9.2 A but pulses 240 A once every millisecond in order to measure the diode temperature. Care must be taken in the PCB layout to keep the parasitic resistance between DIODE and the MMBT3904 low so as not to degrade the measurement. Additionally, a small 100 pF bypass capacitor can be placed in parallel with the MMBT3904 to reduce the effects of noise. The temperature can be read using the READ_TEMPERATURE_1 PMBus command (8Dh). The default warning limit of the LM25056 will cause SMBA to be pulled low if the measured temperature code exceeds 07D0h. The PMBus will also indicate an over temperature fault if the measured temperature code exceeds 0960h. These thresholds can be reprogrammed via the PMBus interface using the OT_WARN_LIMIT (51h) and OT_FAULT_LIMIT (4Fh) commands. If the temperature measurement and protection capability of the LM25056 is not used the DIODE pin should be grounded. Application Section RS +12V MMBT3904 VIN VOUT POL REGULATOR CIN VIN VDD VS+ VS- DIODE ADR2 NC ADR1 NC ADR0 VAUX VREF ENABLE LM25056 SMBA SMBus Interface CVREF VDD SDA CVDD SCL DGND AGND Figure 17. Typical Application Circuit DESIGN-IN PROCEDURE (Refer to Figure 17 for Typical Application Circuit) Shown here is the step-by-step procedure for hardware design of the LM25056. This procedure refers to section numbers that provide detailed information on the following design steps. The recommended design-in procedure is as follows: Current Range, RS: Determine the current range based on the voltage dropped across the sense resistor (RS). Depending on the GAIN setting, the voltage across the sense resistor to get a full scale reading for the current measurement should be 30 mV for GAIN=0 and 60 mV for GAIN=1. Use the Equation 1 to determine the value for RS. Refer to Programming Guide section: After all hardware design is complete, refer to the programming guide for a step by step procedure regarding software. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 11 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com CURRENT RANGE, (RS) The LM25056 monitors current by measuring the voltage across the sense resistor (RS) connected from VS+ to VS -. The required resistor value is calculated from: (1) where IFS is the expected full scale current range based on the current sense gain setting (GAIN). If the voltage across RS reaches VS, the current measurement will reach the full scale measurement. As mentioned before, it is important to limit the current to the full scale reading. While there is internal circuitry intended to maintain the integrity of the other readings in the telemetry, the ADC and MUX are shared and overranging an input may compromise the integrity of the other readings. VS can be set to either 30 mV or 60 mV through software commands. This setting defaults to the sense voltage full scale of 30 mV (GAIN = 0), or it can be set to 60 mV (GAIN = 1). The value can be set via the PMBus with the MFR_DEVICE_SETUP (D9h) command, which defaults to the 30 mV setting. Once the current measurement full scale is known and the VS range is chosen, calculate the shunt based on that input voltage and maximum current range. The maximum load current in normal operation can be used to determine the required power rating for resistor RS. Connections from RS to the LM25056 should be made using Kelvin techniques. In the suggested layout of Figure 18, the small pads at the lower corners of the sense resistor connect only to the sense resistor terminals and not to the traces carrying the high current. With this technique, only the voltage across the sense resistor is applied to VS+ and VS-, eliminating the voltage drop across the high current solder connections. SENSE CURRENT PATH FROM SYSTEM INPUT VOLTAGE TO LOAD SENSE RESISTOR RS VS+ VS- Figure 18. Sense Resistor Connections PC BOARD GUIDELINES The following guidelines should be followed when designing the PC board for the LM25056: * Place the LM25056 close to the board's input connector to minimize trace inductance from the connector to following devices. * Place a small capacitor, CIN, (0.1F) directly adjacent to the VIN and AGND and DGND pins of the LM25056 to help minimize transients which may occur on the input supply line. Transients of several volts can easily occur when the load current is shut off. * Place a 1 F capacitor as close as possible to VREF pin. * Place a 1 F capacitor as close as possible to VDD pin. * The sense resistor (RS) should be placed close to the LM25056. In particular, the traces to the VS+, VS-, and VIN pins should be made as low resistance as practical to ensure maximum current and power measurement accuracy. Connect RS using the Kelvin techniques shown in Figure 18. * The high current path from the board's input to the load and the return path should be parallel and close to each other to minimize loop inductance. * The ground connections for the various components around the LM25056 should be connected directly to each other, and to the LM25056's DGND and AGND pins, and then connected to the system ground at one point. Do not connect the various component grounds to each other through the high current ground line. The 12 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 ground of the MMBT3904 should also be connected to the AGND pin to prevent corruption of the temperature diode measurement. PMBus Command Support The device features an SMBus interface that allows the use of PMBus commands to set warn levels, error masks, and get telemetry on VIN, VAUX, IIN, PIN, and temperature. The supported PMBus commands are shown in Table 1. Table 1. Supported PMBus Commands Number Of Data Bytes Default Value Code Name Function R/W 03h CLEAR_FAULTS Clears the status registers and re-arms the black box registers for updating. Send Byte 0 19h CAPABILITY Retrieves the device capability. R 1 B0h 4Fh OT_FAULT_LIMIT Retrieves or stores over temperature fault limit threshold. R/W 2 0960h 51h OT_WARN_LIMIT Retrieves or stores over temperature warn limit threshold. R/W 2 07D0h 57h VIN_OV_WARN_LIMIT Retrieves or stores input over-voltage warn limit threshold. R/W 2 0FFFh 58h VIN_UV_WARN_LIMIT Retrieves or stores input under-voltage warn limit threshold. R/W 2 0000h 78h STATUS BYTE Retrieves information about the parts operating status. R 1 01h 79h STATUS_WORD Retrieves information about the parts operating status. R 2 1001h 7Ch STATUS_INPUT Retrieves information about input status. R 1 00h 7Dh STATUS_TEMPERATURE Retrieves information about temperature status. R 1 00h 7Eh STATUS_CML Retrieves information about communications status. R 1 00h 80h STATUS_MFR_SPECIFIC Retrieves information about manufacturer specific device status. R 1 10h 88h READ_VIN Retrieves input voltage measurement. R 2 0000h 8Dh READ_TEMPERATURE_1 Retrieves temperature measurement. R 2 0000h 99h MFR_ID Retrieves manufacturer ID in ASCII characters (NSC). R 3 4Eh 53h 43h 9Ah MFR_MODEL Retrieves Part number in ASCII characters. (LM25056). R 8 4Ch 4Dh 32h 35h 30h 35h 36h 00h 9Bh MFR_REVISION Retrieves part revision letter/number in ASCII (e.g., AA). R 2 41h 41h D0h MFR_SPECIFIC_00 MFR_READ_VAUX Retrieves auxiliary voltage measurement. R 2 0000h D1h MFR_SPECIFIC_01 MFR_READ_IIN Retrieves input current measurement. R 2 0000h D2h MFR_SPECIFIC_02 MFR_READ_PIN Retrieves input power measurement. R 2 0000h D3h MFR_SPEICIFIC_03 MFR_IIN_OC_WARN_LIMIT Retrieves or stores input current limit warn threshold. R/W 2 0FFFh D4h MFR_SPECIFIC_04 MFR_PIN_OP_WARN_LIMIT Retrieves or stores input power limit warn threshold. R/W 2 0FFFh D5h MFR_SPECIFIC_05 MFR_READ_PIN_PEAK Retrieves maximum input power measurement. R 2 0000h Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 13 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Table 1. Supported PMBus Commands (continued) Number Of Data Bytes Default Value Code Name Function R/W D6h MFR_SPECIFIC_06 MFR_CLEAR_PIN_PEAK Resets the contents of the peak input power register to zero. Send Byte 0 D8h MFR_SPECIFIC_08 MFR_ALERT_MASK Retrieves or stores user SMBA fault mask. R/W 2 0000h D9h MFR_SPECIFIC_09 MFR_DEVICE_SETUP Retrieves or stores information about the LM25056 setup. R/W 1 0000h DAh MFR_SPECIFIC_10 MFR_BLOCK_READ Retrieves most recent diagnostic and telemetry information in a single transaction. R 12 0080h 0000h 0000h 0000h 0000h 0000h DBh MFR_SPECIFIC_11 MFR_SAMPLES_FOR_AVG Exponent value AVGN for number of samples to be averaged, range = 00h to 0Ch . R/W 1 00h DCh MFR_SPECIFIC_12 MFR_READ_AVG_VIN Retrieves averaged input voltage measurement. R 2 0000h DDh MFR_SPECIFIC_13 MFR_READ_AVG_VAUX Retrieves averaged auxiliary voltage measurement. R 2 0000h DEh MFR_SPECIFIC_14 MFR_READ_AVG_IIN Retrieves averaged input current measurement. R 2 0000h DFh MFR_SPECIFIC_15 MFR_READ_AVG_PIN Retrieves averaged input power measurement. R 2 0000h E0h MFR_SPECIFIC_16 MFR_BLACK_BOX_READ Captures diagnostic and telemetry information which are latched when an SMBA occurs after faults have been cleared. R 12 0080h 0000h 0000h 0000h 0000h 0000h E1h MFR_SPECIFIC_17 MFR_DIAGNOSTIC_WORD_READ Manufacturer-specific parallel of the STATUS_WORD to convey all FAULT/WARN data in a single transaction. R 2 0080h E2h MFR_SPECIFIC_18 MFR_AVG_BLOCK_READ Retrieves most recent average telemetry and diagnostic information in a single transaction. R 12 0080h 0000h 0000h 0000h 0000h 0000h E3h MFR_SPECIFIC_19 MFR_VAUX_OV_WARN_LIMIT Retrieves or stores auxiliary over-voltage warn limit threshold. R 2 0FFFh E4h MFR_SPECIFIC_20 MFR_VAUX_UV_WARN_LIMIT Retrieves or stores auxiliary under-voltage warn limit threshold. R 2 0000h STANDARD PMBus Commands CLEAR_FAULTS (03h) The CLEAR_FAULTS command is a standard PMBus command that resets all stored warning and fault flags and the SMBA signal. If a fault or warning condition still exists when the CLEAR_FAULTS command is issued, the SMBA signal may not clear or will re-assert almost immediately. This command uses the PMBus send byte protocol. CAPABILITY (19h) The CAPABILITY command is a standard PMBus command that returns information about the PMBus functions supported by the LM25056. This command is read with the PMBus read byte protocol. 14 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Table 2. CAPABILITY Register Value Meaning Default B0h Supports Packet Error Check, 400Kbits/sec, Supports SMBus Alert B0h OT_FAULT_LIMIT (4Fh) The OT_FAULT_LIMIT is a standard PMBus command that allows configuring or reading the threshold for the overtemperature fault detection. Reading and writing to this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read or write word protocol. If the measured temperature exceeds this value, an Overtemperature fault is triggered, OT Fault flags are set and the SMBA signal is asserted. Table 3. OT_FAULT_LIMIT Register Value Meaning Default 0h - 0FFEh Overtemperature Fault Threshold Value 0960h 0FFFh Overtemperature Fault detection disabled n/a OT_WARN_LIMIT (51h) The OT_WARN_LIMIT is a standard PMBus command that allows configuring or reading the threshold for the overtemperature warning detection. Reading and writing to this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read or write word protocol. If the measured temperature exceeds this value, an Overtemperature warning is triggered and the OT Warning flags are set and the SMBA signal is asserted. Table 4. OT_WARN_LIMIT Register Value Meaning Default 0h - 0FFEh Overtemperature Warn Threshold Value 07D0h 0FFFh Overtemperature Warn detection disabled n/a VIN_OV_WARN_LIMIT (57h) The VIN_OV_WARN_LIMIT is a standard PMBus command that allows configuring or reading the threshold for the VIN overvoltage warning detection. Reading and writing to this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read or write word protocol. If the measured value of VIN rises above the value in this register, VIN OV Warn flags are set and the SMBA signal is asserted. Table 5. VIN_OV_WARN_LIMIT Register Value Meaning Default 0h - 0FFEh VIN Overvoltage Warning detection threshold 0FFFh (disabled) 0FFFh VIN Overvoltage Warning disabled n/a VIN_UV_WARN_LIMIT (58h) The VIN_UV_WARN_LIMIT is a standard PMBus command that allows configuring or reading the threshold for the VIN undervoltage warning detection. Reading and writing to this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read or write word protocol. If the measured value of VIN falls below the value in this register, VIN UV Warn flags are set and the SMBA signal is asserted. Table 6. VIN_UV_WARN_LIMIT Register Value Meaning Default 1h - 0FFFh VIN Undervoltage Warning detection threshold 0000h (disabled) 0000h VIN Undervoltage Warning disabled n/a Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 15 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com STATUS_BYTE (78h) The STATUS_BYTE is a standard PMBus command that returns the value of a number of flags indicating the state of the LM25056. Accesses to this command should use the PMBus read byte protocol. To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command issued. Table 7. STATUS_BYTE Definitions Bit Name Meaning Default 7 BUSY Not supported 0 6 OFF Not supported 0 5 VOUT_OV Not supported 0 4 IOUT_OC Not supported 0 3 VIN_UV An input undervoltage fault has occurred 0 2 TEMPERATURE A temperature fault or warning has occurred 0 1 CML A Communication Fault has occurred 0 0 NONE OF THE ABOVE A fault or warning not listed in bits [7:1] has occurred 1 STATUS_WORD (79h) The STATUS_WORD is a standard PMBus command that returns the value of a number of flags indicating the state of the LM25056. Accesses to this command should use the PMBus read word protocol. To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command issued. The INPUT and VIN UV flags will default to 1 on startup. Table 8. STATUS_WORD Definitions Bit Name Meaning Default 15 VOUT Not supported 0 14 IOUT/POUT Not supported 0 13 INPUT An input voltage or current fault has occurred 0 12 MFR A manufacturer specific fault or warning has occurred 1 11 POWER_GOOD# Not supported 0 10 FANS Not supported 0 9 OTHER Not supported 0 8 UNKNOWN Not supported 0 7 BUSY Not supported 0 6 OFF Not supported 0 5 VOUT_OV Not supported 0 4 IOUT_OC Not supported 0 3 VIN_UV An input undervoltage fault has occurred 0 2 TEMPERATURE A temperature fault or warning has occurred 0 1 CML A communication fault has occurred 0 0 NONE OF THE ABOVE A fault or warning not listed in bits [7:1] has occurred 1 STATUS_INPUT (7Ch) The STATUS_INPUT is a standard PMBus command that returns the value of the of a number of flags related to input voltage, current, and power. Accesses to this command should use the PMBus read byte protocol. To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command issued. Table 9. STATUS_INPUT Definitions 16 Bit Name Meaning Default 7 VIN OV Fault Not supported 0 6 VIN OV Warn An input overvoltage warning has occurred 0 5 VIN UV Warn An input undervoltage warning has occurred 0 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Table 9. STATUS_INPUT Definitions (continued) Bit Name Meaning Default 4 VIN UV Fault Not supported 0 3 Insufficient Voltage Not supported 0 2 IIN OC Fault Not supported 0 1 IIN OC Warn An input overcurrent warning has occurred 0 0 PIN OP Warn An input overpower warning has occurred 0 STATUS_TEMPERATURE (7Dh) The STATUS TEMPERATURE is a standard PMBus command that returns the value of the of a number of flags related to the temperature telemetry value. Accesses to this command should use the PMBus read byte protocol. To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command issued. Table 10. STATUS_TEMPERATURE Definitions Bit Name Meaning Default 7 OT FAULT An overtemperature fault has occurred 0 6 OT WARN An overtemperature warning has occurred 0 5 UT WARN Not supported 0 4 UT FAULT Not supported 0 3 reserved Not supported 0 2 reserved Not supported 0 1 reserved Not supported 0 0 reserved Not supported 0 STATUS_CML (7Eh) The STATUS_CML is a standard PMBus command that returns the value of a number of flags related to communication faults. Accesses to this command should use the PMBus read byte protocol. To clear bits in this register, a CLEAR FAULTS command should be issued. Table 11. STATUS_CML Definitions Bit Meaning Default 7 Invalid or unsupported command received 0 6 Invalid or unsupported data received 0 5 Packet Error Check failed 0 4 Not supported 0 3 Not supported 0 2 Reserved 0 1 Miscellaneous communications fault has occurred 0 0 Not supported 0 STATUS_MFR_SPECIFIC (80h) The STATUS_MFR_SPECIFIC command, is a standard PMBus command that contains manufacturer specific status information. Accesses to this command should use the PMBus read byte protocol. To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command should be issued. Table 12. STATUS_MFR_SPECIFIC Definitions Bit Meaning Default 7 Not supported 0 6 Not supported 0 5 Not supported 0 4 Defaults loaded 1 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 17 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Table 12. STATUS_MFR_SPECIFIC Definitions (continued) Bit Meaning Default 3 Not supported 0 2 Not supported 0 1 A VAUX Overvoltage Warning has occurred 0 0 A VAUX Undervoltage Warning has occurred 0 READ_VIN (88h) The READ_VIN is a standard PMBus command that returns the 12 bit measured value of the input voltage as read from the VIN pin. Reading this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read word protocol. This value is also used internally for the VIN Over and Under Voltage Warning detection. Table 13. READ_VIN Register Value Meaning Default 0h - 0FFFh Measured value for VIN 0000h READ_TEMPERATURE_1 (8Dh) The READ_TEMPERATURE_1 is a standard PMBus command that returns the signed value of the temperature measured by the external temperature sense diode. Reading this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read word protocol. This value is also used internally for the Over Temperature Fault and Warning detection. This data has a range of -256C to + 255C after the coefficients are applied. Table 14. READ_TEMPERATURE_1 Register Value Meaning Default 0h - 0FFFh Measured value for TEMPERATURE 0000h MFR_ID (99h) The MFR_ID is a standard PMBus command that returns the identification of the manufacturer. To read the manufacturer ID, use the PMBus block read protocol. Table 15. MFR_ID Register Byte Name Value 0 Number of bytes 03h 1 MFR ID-1 4Eh `N' 2 MFR ID-2 53h `S' 3 MFR ID-3 43h `C' MFR_MODEL (9Ah) The MFR_MODEL is a standard PMBus command that returns the part number of the chip. To read the manufacturer model, use the PMBus block read protocol. Table 16. MFR_MODEL Register 18 Byte Name Value 0 Number of bytes 08h 1 MFR ID-1 4Ch `L' 2 MFR ID-2 4Dh `M' 3 MFR ID-3 32h `2' 4 MFR ID-4 35h `5' 5 MFR ID-5 30h `0' 6 MFR ID-6 35h `5' Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Table 16. MFR_MODEL Register (continued) Byte Name Value 7 MFR ID-7 36h `6' 8 MFR ID-8 00h MFR_REVISION (9Bh) The MFR_REVISION is a standard PMBus command that returns the revision level of the part. To read the manufacturer revision, use the PMBus block read protocol. Table 17. MFR_REVISION Register Byte Name Value 0 Number of bytes 02h 1 MFR ID-1 41h `A' 2 MFR ID-2 41h `A' Manufacturer Specific PMBus Commands MFR_SPECIFIC_00: MFR_READ_VAUX (D0h) The MFR_READ_VAUX command will report the 12-bit ADC measured auxiliary voltage. Voltages greater than or equal to 1.199V to AGND will be reported at plus full scale (0FFFh). Voltages less than or equal to 0V referenced to AGND will be reported as 0 (0000h). Coefficients for the VAUX value are dependent on the value of the external divider (if used). To read data from the MFR_READ_VAUX command, use the PMBus Read Word protocol. Table 18. MFR_READ_VAUX Register Value Meaning Default 0h - 0FFFh Measured value for AUX input 0000h MFR_SPECIFIC_01: MFR_READ_IIN (D1h) The MFR_READ_IIN command will report the 12-bit ADC measured current sense voltage. To read data from the MFR_READ_IIN command, use the PMBus Read Word protocol. Reading this register should use the coefficients shown in the Table 38 Table. Please see the section on coefficient calculations to calculate the values to use. Table 19. MFR_READ_IIN Register Value Meaning Default 0h - 0FFFh Measured value for input current sense voltage 0000h MFR_SPECIFIC_02: MFR_READ_PIN (D2h) The MFR_READ_PIN command will report the upper 12-bits of the VIN x IIN product as measured by the 12-bit ADC. To read data from the MFR_READ_PIN command, use the PMBus Read Word protocol. Reading this register should use the coefficients shown in the Table 38 Table. Table 20. MFR_READ_PIN Register Value Meaning Default 0h - 0FFFh Value for input current x input voltage 0000h MFR_SPECIFIC_03: MFR_IIN_OC_WARN_LIMIT (D3h) The MFR_IIN_OC_WARN_LIMIT PMBus command sets the input overcurrent warning threshold. In the event that the input current rises above the value set in this register, the IIN Overcurrent flags are set in the status registers and the SMBA is asserted. To access the MFR_IIN_OC_WARN_LIMIT register, use the PMBus Read/Write Word protocol. Reading/writing to this register should use the coefficients shown in the Table 38 Table. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 19 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Table 21. MFR_IIN_OC_WARN_LIMIT Register Value Meaning Default 0h - 0FFEh Value for input over current warn limit 0FFFh 0FFFh Input over current warning disabled n/a MFR_SPECIFIC_04: MFR_PIN_OP_WARN_LIMIT (D4h) The MFR_PIN_OP_WARN_LIMIT PMBus command sets the input overpower warning threshold. In the event that the input power rises above the value set in this register, the PIN Overpower flags are set in the status registers and the SMBA is asserted. To access the MFR_PIN_OP_WARN_LIMIT register, use the PMBus Read/Write Word protocol. Reading/writing to this register should use the coefficients shown in the Table 38 Table. Table 22. MFR_PIN_OP_WARN_LIMIT Register Value Meaning Default 0h - 0FFEh Value for input over power warn limit 0FFFh 0FFFh Input over power warning disabled n/a MFR_SPECIFIC_05: MFR_READ_PIN_PEAK (D5h) The MFR_READ_PIN_PEAK command will report the maximum input power measured since a Power On reset or the last MFR_CLEAR_PIN_PEAK command. To access the MFR_READ_PIN_PEAK command, use the PMBus Read Word protocol. Use the coefficients shown in the Table 38 Table. Table 23. MFR_READ_PIN_PEAK Register Value Meaning Default 0h - 0FFEh Maximum Value for input current x input voltage since reset or last clear 0000h MFR_SPECIFIC_06: MFR_CLEAR_PIN_PEAK (D6h) The MFR_CLEAR_PIN_PEAK command will clear the MFR_READ_PIN_PEAK register. This command uses the PMBus Send Byte protocol. MFR_SPECIFIC_08: MFR_ALERT_MASK (D8h) The MFR_ALERT_MASK is used to mask the SMBA when a specific fault or warning has occurred. Each bit corresponds to one of the 9 different analog and digital faults or warnings that would normally result in an SMBA being asserted. When the corresponding bit is high, that condition will not cause the SMBA to be asserted. If that condition occurs, the registers where that condition is captured will still be updated (STATUS registers, MFR_DIAGNOSTIC_WORD, OT_FAULT_LIMIT). This register is accessed with the PMBus Read / Write Word protocol. Table 24. MFR_ALERT_MASK Definitions 20 BIT NAME DEFAULT 15 VAUX UNDERVOLTAGE WARN 0 14 IIN LIMIT WARN 0 13 VIN UNDERVOLTAGE WARN 0 12 VIN OVERVOLTAGE WARN 0 11 Reserved, always set to 0 0 10 OVERTEMPERATURE WARN 0 9 VAUX OVERVOLTAGE WARN 0 8 OVERPOWER LIMIT WARN 0 7 Reserved, always set to 0 0 6 Reserved, always set to 0 0 5 Reserved, always set to 0 0 4 Reserved, always set to 0 0 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Table 24. MFR_ALERT_MASK Definitions (continued) BIT NAME DEFAULT 3 Reserved, always set to 0 0 2 OVERTEMPERATURE FAULT 0 1 CML FAULT (Communications Fault) 0 0 Reserved, always set to 0 0 MFR_SPECIFIC_09: MFR_DEVICE_SETUP (D9h) The MFR_DEVICE_SETUP command may be used to define operation or reset the LM25056 under host control. This command is accessed with the PMBus read / write byte protocol. Table 25. MFR_DEVICE_SETUP Byte Format Bit Name 7 Reserved, always set to 0 6 Reserved, always set to 0 5 Reserved, always set to 0 4 Current sense gain 3 Reserved, always set to 0 2 Reserved, always set to 0 1 Reserved, always set to 0 0 Software reset Meaning GAIN = 0, Low setting (30mV) GAIN = 1, High setting (60mV) 0 = Default 1 = Reset Within this command byte, the current sense gain bit changes the range and coefficients used for current and power measurements as well as relevant warning registers. The software reset bit is used to reset the LM25056. Writing a 1 to this bit will reset the device back to its default startup values. MFR_SPECIFIC_10: MFR_BLOCK_READ (DAh) The MFR_BLOCK_READ command concatenates the MFR_DIAGNOSTIC_WORD_READ with input telemetry information (IIN, VAUX, VIN, PIN) as well as READ_TEMPERATURE_1 to capture all of the operating information of the LM25056 in a single SMBus transaction. The block is 12 bytes long with telemetry information being sent out in the same manner as if an individual READ_XXX command had been issued (shown below). The contents of the block read register are updated every clock cycle (85 ns) as long as the SMBus interface is idle. MFR_BLOCK_READ also ensures that the VIN, VAUX, IIN and PIN measurements are all time-aligned whereas there is a chance they may not be if retrieved with individual PMBus commands. The Block Read command is read via the PMBus block read protocol. Table 26. MFR_BLOCK_READ Register Format Byte Count (always 12) (1 byte) DIAGNOSTIC WORD (1 Word) IIN_BLOCK (1 Word) VAUX_BLOCK (1 Word) VIN_BLOCK (1 Word) PIN_BLOCK (1 Word) TEMP_BLOCK (1 Word) Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 21 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com MFR_SPECIFIC_11: MFR_SAMPLES_FOR_AVG (DBh) The MFR_SAMPLES_FOR AVG is a manufacturer specific command for setting the number of samples used in computing the average values for IIN, VIN, VAUX, PIN. The decimal equivalent of the AVGN nibble is the power of 2 samples (e.g. AVGN=12 equates to 4096 samples used in computing the average). The LM25056 supports average numbers of 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096. The MFR_SAMPLES_FOR_AVG number applies to average values of IIN, VIN, VAUX, PIN simultaneously. The LM25056 uses simple averaging. This is accomplished by summing consecutive results up to the number programmed, then dividing by the number of samples. Averaging is calculated according to the following sequence: Y = (X(N) + X(N-1) + ... + X(0)) / N (2) When the averaging has reached the end of a sequence (for example, 4096 samples are averaged), then a whole new sequence begins that will require the same number of samples (in this example, 4096) to be taken before the new average is ready. Table 27. MFR_SAMPLES_FOR_AVERAGE AVGN N = 2AVGN Averaging/Register Update Period (ms) 0000 1 1 0001 2 2 0010 4 4 0011 8 8 0100 16 16 0101 32 32 0110 64 64 0111 128 128 1000 256 256 1001 512 512 1010 1024 1024 1011 2048 2048 1100 4096 4096 Note that a change in the MFR_SAMPLES_FOR_AVG register will not be reflected in the average telemetry measurements until the present averaging interval has completed. The default setting for AVGN is 0000 and therefore the average telemetry will mirror the instantaneous telemetry until a value higher than zero is programmed. The MFR_SAMPLES_FOR_AVG register is accessed via the PMBus read / write byte protocol. Table 28. MFR_SAMPLES_FOR_AVG Register Value Meaning Default 0h - 0Ch Exponent for number of samples to average over 00h MFR_SPECIFIC_12: MFR_READ_AVG_VIN (DCh) The MFR_READ_AVG_VIN command will report the 12-bit ADC measured input average voltage. If the data is not ready, the returned value will be the previous averaged data. However, if there is no previously averaged data the default value (0000h) will be returned. This data is read with the PMBus Read Word protocol. This register should use the coefficients shown in the Table 38 Table. Table 29. MFR_READ_AVG_VIN Register 22 Value Meaning Default 0h - 0FFFh Average of measured values for input voltage 0000h Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 MFR_SPECIFIC_13: MFR_READ_AVG_VAUX (DDh) The MFR_READ_AVG_AUX command will report the 12-bit ADC measured auxiliary average voltage. If the data is not ready, the returned value will be the previous averaged data. However, if there is no previously averaged data the default value (0000h) will be returned. This data is read with the PMBus Read Word protocol. This register should use the coefficients shown in theTable 38 Table. Table 30. MFR_READ_AVG_VAUX Register Value Meaning Default 0h - 0FFFh Average of measured values for auxiliary voltage 0000h MFR_SPECIFIC_14: MFR_READ_AVG_IIN (DEh) The MFR_READ_AVG_IIN command will report the 12-bit ADC measured current sense average voltage. If the data is not ready, the returned value will be the previous averaged data. However, if there is no previously averaged data the default value (0000h) will be returned. This data is read with the PMBus Read Word protocol. This register should use the coefficients shown in the Table 38 Table. Table 31. MFR_READ_AVG_IIN Register Value Meaning Default 0h - 0FFFh Average of measured values for current sense voltage 0000h MFR_SPECIFIC_15: MFR_READ_AVG_PIN (DFh) The MFR_READ_AVG_PIN command will report the upper 12-bits of the average VIN x IIN product as measured by the 12-bit ADC. If the data is not ready, the returned value will be the previous averaged data. However, if there is no previously averaged data the default value (0000h) will be returned. This data is read with the PMBus Read Word protocol. This register should use the coefficients shown in the Table 38 Table. Table 32. MFR_READ_AVG_PIN Register Value Meaning Default 0h - 0FFFh Average of measured value for input voltage x input current sense voltage 0000h MFR_SPECIFIC_16: MFR_BLACK_BOX_READ (E0h) The MFR_BLACK_BOX_READ command retrieves the MFR_BLOCK_READ data which was latched in at the first assertion of SMBA. It is re-armed with the CLEAR_FAULTS command. It is the same format as the MFR_BLOCK_READ registers, the only difference being that its contents are updated with the SMBA edge rather than the internal clock edge. This command is read with the PMBus Block Read protocol. MFR_SPECIFIC_17: MFR_DIAGNOSTIC_WORD_READ (E1h) The MFR_DIAGNOSTIC_WORD_READ PMBus command will report all of the LM25056 faults and warnings in a single read operation. The standard response to the assertion of the SMBA signal of issuing multiple read requests to various status registers can be replaced by a single word read to the MFR_DIAGNOSTIC_WORD_READ register. The MFR_DIAGNOSTIC_WORD_READ command should be read with the PMBus Read Word protocol. The MFR_DIAGNOSTIC_WORD_READ register is also returned in the MFR_BLOCK_READ, MFR_BLACK_BOX_READ, and MFR_AVG_BLOCK_READ operations. Table 33. MFR_DIAGNOSTIC_WORD_READ Format Bit Name 15 Reserved Meaning Default 14 MFR_IIN_OC_WARN or MFR_PIN_OP_WARN Input Overcurrent or Overpower Warning 0 13 VIN_UV_WARN Input Undervoltage Warning 0 12 VIN_OV_WARN Input Overvoltage Warning 0 11 Reserved 0 0 10 OT_WARN Overtemperature Warning 0 9 MFR_VAUX_UNDERVOLTAGE_WARN VAUX Undervoltage Warning 0 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 23 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Table 33. MFR_DIAGNOSTIC_WORD_READ Format (continued) Bit Name Meaning Default 8 MFR_VAUX_OVERVOLTAGE_WARN VAUX Overvoltage Warning 0 7 CONFIG_PRESET 1 6 Reserved 0 5 Reserved 0 4 Reserved 0 3 Reserved 2 OT__FAULT Over Temperature Fault 0 1 CML_FAULT Communications Fault 0 0 Reserved 0 0 MFR_SPECIFIC_18: MFR_AVG_BLOCK_READ (E2h) The MFR_AVG_BLOCK_READ command concatenates the DIAGNOSTIC_WORD with input average telemetry information (IIN, VAUX, VIN, PIN) as well as TEMPERATURE to capture all of the operating information of the part in a single PMBus transaction. The block is 12 bytes long with telemetry information being sent out in the same manner as if an individual READ_AVG_XXX command had been issued (shown below). AVG_BLOCK_READ also ensures that the VIN, VAUX, IIN, and PIN measurements are all time-aligned whereas there is a chance they may not be if read with individual PMBus commands. To read data from the AVG_BLOCK_READ command, use the SMBus Block Read protocol. Table 34. MFR_AVG_BLOCK_READ Register Format Byte Count (always 12) (1 byte) DIAGNOSTIC WORD (1 word) AVG_IIN (1 word) AVG_VAUX (1 word) AVG_VIN (1 word) AVG_PIN (1 word) TEMPERATURE (1 word) MFR_SPECIFIC_19: VAUX_OV_WARN_LIMIT (E3h) The VAUX_OV_WARN_LIMIT command allows configuring or reading the threshold for the VAUX overvoltage warning detection. Reading and writing to this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read or write word protocol. If the measured value of VAUX rises above the value in this register, VAUX OV Warn flags are set and the SMBA signal is asserted. Table 35. VAUX_OV_WARN_LIMIT Register Value Meaning Default 0h - 0FFEh VAUX Overvoltage Warning detection threshold 0FFFh (disabled) 0FFFh VAUX Overvoltage Warning disabled n/a MFR_SPECIFIC_20: VAUX_UV_WARN_LIMIT (E4h) The VAUX_UV_WARN_LIMIT command allows configuring or reading the threshold for the VAUX undervoltage warning detection. Reading and writing to this register should use the coefficients shown in the Table 38 Table. Accesses to this command should use the PMBus read or write word protocol. If the measured value of VAUX falls below the value in this register, VAUX UV Warn flags are set and the SMBA signal is asserted. Table 36. VAUX_UV_WARN_LIMIT Register 24 Value Meaning Default 1h - 0FFFh VAUX Undervoltage Warning detection threshold 0000h (disabled) 0000h VAUX Undervoltage Warning disabled n/a Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 +12V To load VIN VS- VS+ + VAUX IIN WARNING LIMITS S/H VIN WARNING SYSTEM ADC MUX DIODE VIN_OV_WARN_LIMIT 57h VIN_UV_WARN_LIMIT 58h DATA OUTPUT MFR_SAMPLES_FOR_AVG DBh READ_VIN 88h MFR_READ_AVG_VIN DCh MFR_READ_IIN D1h MFR_READ_AVG_IIN DEh MFR_READ_PIN D2h READ_AVG_PIN DFh MFR_READ_VAUX D0h READ_AVG_VAUX DDh MFR_IIN_OC_WARN_LIMIT D3h MFR_PIN_OP_WARN_LIMIT D4h MFR_VAUX_OV_WARN_LIMIT E3h CMP VIN_OV WARNING STATUS_INPUT 7Ch CMP VIN_UV WARNING STATUS_INPUT 7Ch STATUS_BYTE 78h CMP IIN_OC WARNING STATUS_INPUT 7Ch CMP PIN_OP WARNING STATUS_INPUT 7Ch CMP VAUX_OV WARNING STATUS_MFR_SPECIFIC 80h CMP VAUX_UV WARNING STATUS_MFR_SPECIFIC 80h CMP OT_WARNING_LIMIT STATUS_WORD 79h STATUS_TEMPERATURE 7Dh CMP OT_FAULT_LIMIT STATUS_WORD 79h STATUS_TEMPERATURE 7Dh READ_TEMPERATURE_1 8Dh AVERAGED DATA MFR_VAUX_UV_WARN_LIMIT E4h OT_WARNING_LIMIT 51h READ_PIN_PEAK D5h CLEAR_PIN_PEAK D6h PEAK-HOLD OT_FAULT_LIMIT 4Fh MFR_DIAGNOSTIC_WORD_READ E1h PMBus Interface Figure 19. Command/Register and Alert Flow Diagram Reading and Writing Telemetry Data and Warning Thresholds All measured telemetry data and user programmed warning thresholds are communicated in 12 bit two's compliment binary numbers read/written in 2 byte increments conforming to the Direct format as described in section 8.3.3 of the PMBus Power System Management Protocol Specification 1.1 (Part II). The organization of the bits in the telemetry or warning word is shown in Table 37, where Bit_11 is the most significant bit (MSB) and Bit_0 is the least significant bit (LSB). The decimal equivalent of all warning and telemetry words are constrained to be within the range of 0 to 4095, with the exception of temperature. The decimal equivalent value of the temperature word ranges from 0 to 65535. Table 37. Telemetry and Warning Word Format Byte B7 B6 B5 B4 1 Bit_7 Bit_6 Bit_5 Bit_4 2 0 0 0 0 B3 B2 B1 B0 Bit_3 Bit_2 Bit_1 Bit_0 Bit_11 Bit_10 Bit_9 Bit_8 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 25 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Conversion from direct format to real world dimensions of current, voltage, power, and temperature is accomplished by determining appropriate coefficients as described in section 7.2.1 of the PMBus Power System Management Protocol Specification 1.1 (Part II). According to this specification, the host system converts the values received into a reading of volts, amperes, watts, or other units using the following relationship: where * * * * * X: the calculated "real world" value (volts, amps, watt, etc.) m: the slope coefficient Y: a two byte two's complement integer received from device b: the offset, a two byte, two's complement integer R: the exponent, a one byte two's complement integer (3) R is necessary only in systems where m is required to be an integer (for example, where m may be stored in a register in an integrated circuit). In those cases, R only needs to be large enough to yield the desired accuracy. Table 38. Telemetry and Warning Conversion Coefficients Commands Format Number of Data Bytes m b R Units READ_VIN, MFR_READ_AVG_VIN, VIN_OV_WARN_LIMIT VIN_UV_WARN_LIMIT DIRECT 2 16296 1343 -2 V MFR_READ_VAUX, MFR_READ_AVG_VAUX, MFR_VAUX_OV_WARN_LIMIT MFR_VAUX_UV_WARN_LIMIT DIRECT 2 3416 -4 0 V (1) MFR_READ_IIN, MFR_IIN_OC_WARN_LIMIT, MFR_READ_AVG_IIN , GAIN = 0 DIRECT 2 13797 -1833 -2 A (1) MFR_READ_IIN, MFR_IIN_OC_WARN_LIMIT, MFR_READ_AVG_IIN , GAIN = 1 DIRECT 2 6726 -537 -2 A (1) MFR_READ_PIN, MFR_PIN_OP_WARN_LIMIT, MFR_READ_PIN_PEAK, MFR_READ_AVG_PIN GAIN = 0 DIRECT 2 5501 -2908 -3 W (1) MFR_READ_PIN, MFR_PIN_OP_WARN_LIMIT, MFR_READ_PIN_PEAK, MFR_READ_AVG_PIN GAIN = 1 DIRECT 2 26882 -5646 -4 W DIRECT 2 1580 -14500 -2 C READ_TEMPERATURE_1, OT_FAULT_LIMIT, OT_WARN_LIMIT (1) 26 Condition The coefficients relating to current/power measurements and warning thresholds shown in Table 38 are normalized to a sense resistor (RS) value of 1m. In general, the current/power coefficients can be calculated using the relationships shown in Table 39. Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Table 39. Current and Power Telemetry and Warning Conversion Coefficients (RS in m) Commands Condition Format Number of Data Bytes m b R Units (1) MFR_READ_IIN, MFR_IIN_OC_WARN_LIMIT, MFR_READ_AVG_IIN , GAIN = 0 DIRECT 2 13797 x RS -1833 -2 A MFR_READ_IIN, MFR_IIN_OC_WARN_LIMIT, MFR_READ_AVG_IIN , GAIN = 1 DIRECT 2 6726 x RS -537 -2 A (1) MFR_READ_PIN, MFR_PIN_OP_WARN_LIMIT, MFR_READ_PIN_PEAK, MFR_READ_AVG_PIN GAIN = 0 DIRECT 2 5501 x RS -2908 -3 W (1) MFR_READ_PIN, MFR_PIN_OP_WARN_LIMIT, MFR_READ_PIN_PEAK, MFR_READ_AVG_PIN GAIN = 1 DIRECT 2 26882 x RS -5646 -4 W (1) (1) The coefficients relating to current/power measurements and warning thresholds shown in Table 38 are normalized to a sense resistor (RS) value of 1m. In general, the current/power coefficients can be calculated using the relationships shown in Table 39. Care must be taken to adjust the exponent coefficient, R, such that the values of m and b remain within the range of -32768 to +32767. For example, if a 5 m sense resistor is used, the correct coefficients for the MFR_READ_IIN command with GAIN = 0 would be m = 3363, b = -537, R = -1. A Note on the "b" Coefficient Since b coefficients represent offset, for simplification b is set to zero in the following discussions. Reading Current The current register actually displays a value equivalent to a voltage across the user specified sense resistor, RS. The coefficients enable the data output to be converted to amps. The values shown in the example are based on having the device programmed for a 30 mV current sense range (GAIN = 0). In the 30 mV range, the LSB value is 7.25 V and the full scale range is 29.68 mV. In the 60 mV current sense range (GAIN = 1), the LSB value is 14.87 V and the full scale range in 60.88 mV. Step Example 1. Determine full scale current and shunt value based on 29.68 mV across shunt at full scale.Use either: Example: Application with 250 shunt. (5) (4) or: 2. Determine m': (7) (6) 3. Determine exponent R necessary to set m' to integer value m: Select R to provide integer value of m: (8) (9) R = -2 m = 3450 4. Final values R = -2 b=0 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 27 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Reading Input Voltage Coefficients for VIN are consistent between read telemetry measurements (e.g., READ_VIN, READ_AVG_VIN) and warning thresholds (e.g., VIN_OV_WARN_LIMIT, VIN_UV_WARN_LIMIT). Input voltage values are read/written in Direct format with 12-bit resolution and a 6.14 mV LSB. An example of calculating the PMBus coefficients for input voltage is shown below. Reading the auxiliary voltage (e.g. MFR_READ_VAUX, MFR_READ_AVG_VAUX) and setting the warning threshold (e.g. MFR_VAUX_UV_WARN_LIMIT) is done in similar manner with different coefficients provided in Table 38. Step Example 1. Determine m' based on full scale analog input and full scale digital range: (11) (10) 2. Determine exponent R necessary to set m' to integer value m with Select R to provide 5 digit accuracy for the integer value of m (which desired accuracy: would be 16295 in this example): (12) (13) R = -2 m = 16295 3. Final values R = -2 b =0 Reading Power The power calculation of the LM25056 is a relative power calculation meaning that full scale of the power register corresponds to simultaneous full scale values in the current register and voltage register such that the power register has the following relationship based on decimal equivalents of the register contents: PIN = IIN x VIN 4095 (14) For this reason power coefficients will also vary depending on the shunt value and must be calculated for each application. The power LSB will vary depending on shunt value according to 374 mW/RS for the GAIN=1 range or 182 mW/RS for the GAIN=0 range. Step Example 1. Determine full scale power from known full scale of input current and input voltage Example: Application with 250 shunt. (16) (15) 2. Determine m': (18) (17) 3. Optional: Determine exponent R necessary to set m' to integer value m with desired accuracy: Select R (in this case selected to provide 4 digit accuracy for the integer value of m): (19) (20) R = -4 m = 13728 4. Final values R = -4 b=0 28 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 Determining Telemetry Coefficients Empirically with Linear Fit The coefficients for telemetry measurements and warning thresholds presented in Table 38 are adequate for the majority of applications. Current and power coefficients must be calculated per application as they are dependent on the value of the sense resistor, RS, used. Table 39 provides the equations necessary for calculating the current and power coefficients for the general case. The small signal nature of the current measurement make it and the power measurement more susceptible to PCB parasitics than other telemetry channels. This may cause slight variations in the optimum coefficients (m, b, R) for converting from Direct format digital values to real-world values (e.g., amps and watts). The optimum coefficients can be determined empirically for a specific application and PCB layout using two or more measurements of the telemetry channel of interest. The current coefficients can be determined using the following method: 1. While the LM25056 is in normal operation measure the voltage across the sense resistor using kelvined test points and a high accuracy DVM while controlling the load current. Record the integer value returned by the MFR_READ_AVG_IIN command (with the MFR_SAMPLES_FOR_AVG set to a value greater than 0) for two or more voltages across the sense resistor. For best results, the individual MFR_READ_AVG_IIN measurements should span nearly the full scale range of the current (For example, voltage across RS of 5mV and 20mV). 2. Convert the measured voltages to currents by dividing them by the value of RS. For best accuracy the value of RS should be measured. Table 40 assumes a sense resistor value of 5 m. Table 40. Measurements for linear fit determination of current coefficients: Measured voltage across RS (V) Measured Current (A) READ_AVG_IIN (integer value) 0.005 1 672 0.01 2 1362 0.02 4 2743 3. Using the spreadsheet or math program of your choice determine the slope and the y-intercept of the returned by the MFR_READ_AVG_IIN command values versus the measured current. For the data shown in Table 39: (a) MFR_READ_AVG_IN value = slope x (Measured Current) + (y-intercept) (b) slope = 690.4 (c) y-intercept = -18.5 4. To determine the `m' coefficient, simply shift the decimal point of the calculated slope to arrive at at integer with a suitable number of significant digits for accuracy (typically 4) while staying with the range of -32768 to +32767. This shift in the decimal point equates to the `R' coefficient. For the slope value shown above, the decimal point would be shifted to the right once hence R = -1. 5. Once the `R' coefficient has been determined, the `b' coefficient is found by multiplying the y-intercept by 10R . In this case the value of b = -185. (a) Calculated Current Coefficients: (b) m = 6904 (c) b = -185 (d) R = -1 where * * * * * X: the calculated "real world" value (volts, amps, watts, temperature) m: the slope coefficient, is the two byte, two's complement integer Y: a two byte two's complement integer received from device b: the offset, a two byte, two's complement integer R: the exponent, a one byte two's complement integer (21) Step 5 can be repeated to determine the coefficients of any telemetry channel simply by substituting measured current for some other parameter (e.g., power, voltage, etc.). Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 29 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com Writing Telemetry Data There are several locations that will require writing data if their optional usage is desired. Use the same coefficients previously calculated for your application, and apply them using this method as prescribed by the PMBus revision section 7.2.2 "Sending a Value" where * * * * * X: the calculated "real world" value (volts, amps, watts, temperature) m: the slope coefficient, is the two byte, two's complement integer Y: a two byte two's complement integer to send to the device b: the offset, a two byte, two's complement integer R: the exponent, a one byte two's complement integer (22) PMBus Address Lines (ADR0, ADR1, ADR2) The three address lines are to be set high (connect to VDD), low (connect to GND), or open to select one of 27 addresses for communicating with the LM25056. These lines are read after the ENABLE pin is returned high, and the VDD and VREF are out of a POR condition. Table 41 depicts 7-bit addresses (eighth bit is read/write bit): Table 41. Device Addressing 30 ADR2 ADR1 ADR0 Decoded Address Z Z Z 40h Z Z 0 41h Z Z 1 42h Z 0 Z 43h Z 0 0 44h Z 0 1 45h Z 1 Z 46h Z 1 0 47h Z 1 1 10h 0 Z Z 11h 0 Z 0 12h 0 Z 1 13h 0 0 Z 14h 0 0 0 15h 0 0 1 16h 0 1 Z 17h 0 1 0 50h 0 1 1 51h 1 Z Z 52h 1 Z 0 53h 1 Z 1 54h 1 0 Z 55h 1 0 0 56h 1 0 1 57h 1 1 Z 58h 1 1 0 59h 1 1 1 5Ah Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 SMBus Communications Timing Requirements tR SCL tF tLOW VIH VIL tHIGH tHD;DAT tHD;STA tSU;STA tSU;STO tSU;DAT SDA VIH VIL tBUF P S S P Figure 20. SMBus Timing Diagram Table 42. SMBus Timing Definition (1) (2) (3) (4) (5) (6) Symbol Parameter Limits Units Min Max fSMB SMBus Operating Frequency 10 400 tBUF Bus free time between Stop and Start Condition 1.3 s tHD:STA Hold time after (Repeated) Start Condition. After this period, the first clock is generated. 0.6 s tSU:STA Repeated Start Condition setup time 0.6 s tSU:STO Stop Condition setup time 0.6 s tHD:DAT Data hold time 300 ns tSU:DAT Data setup time 100 tTIMEOUT Clock low time-out 25 Comments kHz ns 35 ms See (1) tLOW Clock low period 1.5 s tHIGH Clock high period 0.6 s See (2) tLOW:SEXT Cumulative clock low extend time (slave device) 25 ms See (3) tLOW:MEXT Cumulative low extend time (master device) 10 ms See (4) tF Clock or Data Fall Time 20 300 ns See (5) tR Clock or Data Rise Time 20 300 ns See (6) Devices participating in a transfer will timeout when any clock low exceeds the value of tTIMEOUT,MIN of 25 ms. Devices that have detected a timeout condition must reset the communication no later than tTIMEOUT,MAX of 35 ms. The maximum value must be adhered to by both a master and a slave as it incorporates the cumulative stretch limit for both a master (10ms) and a slave (25ms). tHIGH MAX provides a simple method for devices to detect bus idle conditions. tLOW:SEXT is the cumulative time a slave device is allowed to extend the clock cycles in one message from the initial start to the stop. If a slave exceeds this time, it is expected to release both its clock and data lines and reset itself. tLOW:MEXT is the cumulative time a master device is allowed to extend its clock cycles within each byte of a message as defined from start-to-ack, ack-to-ack, or ack-to-stop. Fall time is defined as follows: tF = 0.9 VDD to (VILMAX - 0.15) Rise time is defined as follows: tR = ( VILMAX - 0.15) to (VIHMIN + 0.15) Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 31 LM25056 SNVS784A - JANUARY 2012 - REVISED APRIL 2013 www.ti.com SMBA Response The SMBA effectively has two masks: 1. The Alert Mask Register at D8h, and 2. The ARA Automatic Mask. The ARA Automatic Mask is a mask that is set in response to a successful ARA read. An ARA read operation returns the PMBus&trade; address of the lowest addressed part on the bus that has its SMBA asserted. A successful ARA read means that THIS part was the one that returned its address. When a part responds to the ARA read, it releases the SMBA signal. When the last part on the bus that has an SMBA set has successfully reported its address, the SMBA signal will de-assert. The way that the LM25056 releases the SMBA signal is by setting the ARA Automatic mask bit for all fault conditions present at the time of the ARA read. All status registers will still show the fault condition, but it will not generate and SMBA on that fault again until the ARA Automatic mask is cleared by the host issuing a Clear Fault command to this part. This should be done as a routine part of servicing an SMBA condition on a part, even if the ARA read is not done. Figure 21 depicts a schematic version of this flow. From other fault inputs SMBAlert Fault Condition Alert Mask D8h From PMBus Set ARA Operation Flag Succeeded ARA Auto Mask Clear Clear Fault Command Received Figure 21. Typical Flow Schematic for SMBA Fault 32 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 LM25056 www.ti.com SNVS784A - JANUARY 2012 - REVISED APRIL 2013 REVISION HISTORY Changes from Original (April 2013) to Revision A * Page Changed layout of National Data Sheet to TI format .......................................................................................................... 32 Submit Documentation Feedback Copyright (c) 2012-2013, Texas Instruments Incorporated Product Folder Links: LM25056 33 PACKAGE OPTION ADDENDUM www.ti.com 13-Apr-2018 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LM25056PSQ/NOPB NRND WQFN NHZ 24 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L25056P LM25056PSQE/NOPB NRND WQFN NHZ 24 250 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L25056P (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. 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Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 13-Apr-2018 Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 30-Apr-2018 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM25056PSQ/NOPB WQFN NHZ 24 1000 178.0 12.4 4.3 5.3 1.3 8.0 12.0 Q1 LM25056PSQE/NOPB WQFN NHZ 24 250 178.0 12.4 4.3 5.3 1.3 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 30-Apr-2018 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM25056PSQ/NOPB WQFN NHZ 24 1000 210.0 185.0 35.0 LM25056PSQE/NOPB WQFN NHZ 24 250 210.0 185.0 35.0 Pack Materials-Page 2 MECHANICAL DATA NHZ0024B SQA24B (Rev A) www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated (TI) reserves the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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