DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP General Description Features The AAT4685 OVPSwitchTM is a member of Skyworks' Application Specific Power MOSFETTM (ASPMTM) product family. It is an N-channel MOSFET power switch with precise over-voltage protection control, designed to protect low-voltage systems against high-voltage faults up to +28V. It also integrates over-current protection (OCP), battery over-voltage protection (BOVP) and overtemperature protection (OTP). * VIN Range: 3.0V - 28V * OVP Threshold Setting Range: 4V - 7V Fixed: 5.85V and 6.8V Adjustable * Fast OVP Response: 1s (max) Response to Over-Voltage Transient * OVP Recovery Delay Time: 8ms * Over-Current Protection * Adjustable 0.3 - 1.8A * Battery OVP 4.35V * Thermal Shutdown Protection * Low Quiescent Current 600A Typical 100A Typical Standby Current * Under-Voltage Lockout * 120m Typical RDS(ON) at 5.0V * Active Low Enable with Internal 200k Pull-Down Resistor * Input Supply Power Good Indicator, Open Drain * OVP/OCP/BOVP/OT Fault Indicator, Open Drain * Temperature Range: -40C to 85C * 3x3mm TDFN-12 Package When the input voltage exceeds the programmed overvoltage threshold, the N-channel MOSFET switch will be turned off to prevent damage to the output load circuits. An external resistor divider is adopted to program the adjustable version over-voltage trip point. Over-current protection protects the case of output short circuits by disconnecting the load from the input supply. A battery voltage monitor is integrated and disconnect the IN and OUT when the battery voltage exceed its rated voltage. The AAT4685 also monitors its own die temperature and OVP switch off if it becomes too hot. The AAT4685 includes an under-voltage lockout (UVLO) protection circuit, which puts the device into sleep mode at low input voltages only consuming 100A current. It also includes two indicators: input supply power good indicator (POK) which is always active whether EN is low or high, and a fault flag indicator (FLT) which goes to active low when a fault condition (OV, OC, BOV and OT) occurs at EN = low. Applications *Cell Phones *Digital Still Cameras *MP3 *Personal Data Assistants (PDAs) The AAT4685 is offered in a Pb-free, 3x3mm 12-pin TDFN package with a pin-out optimized for safety and is specified for operation over the -40C to +85C ambient temperature range. Typical Application VIN 3.0V - 28V IN OVP C1 1F ROVP2 ROCP VOUT OUT AAT4685 ROVP1 OCP IC EN GND Fault Flag FLT POK BAT BOVP C2 1F VIO VIO Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 1 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Pin Descriptions Pin # Symbol 1 2 3 OCP IC EN 4 POK 5,6 7,8 9 OUT IN GND 10 FLT 11 BOVP 12 OVP (N/C) Function Over-current protection threshold input. Connect resistor to ground to set OCP limit. Internally connected. Connect this pin to ground. Active low enable with internal 200k resistor pull down to GND Input supply power-good status pin, open-drain. The POK function is always active whether EN is low or high. Connect a 1k to 100k pull-up resistor to the logic I/O voltage of the host system. Output. Connect a 0.1F~47uF capacitor from OUT to GND. Power input pin. Connect 1F capacitor from IN to GND. Ground connection. Open-drain output. Active low when input over-voltage, input over-current, battery over-voltage, or over temperature and EN = low. The FLT pin goes to high impedance state when EN = high. Connect a 1k to 100k pull-up resistor to the logic I/O voltage of the host system. Battery voltage sense input. Connect to battery positive terminal through a 100k resistor to limit the current in case of a short circuit condition. Over-voltage protection threshold input (Adjustable only). Fixed version not connected. Pin Configuration TDFN33-12 (Top View) OCP IC EN POK OUT OUT 2 1 12 2 11 3 10 4 9 5 8 6 7 OVP (N/C) BOVP FLT GND IN IN Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Absolute Maximum Ratings1 Symbol VIN VN VP IMAX TJ TS TLEAD Description IN to GND BOVP, OVP , OCP, OUT , IC to GND FLT, EN, POK to GND Maximum Continuous Switch Current Operating Junction Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value Units -0.3 to 28 -0.3 to VP +0.3 -0.3 to 7.5 1.9 -40 to 150 -65 to 150 300 V V V A C C C Value Units 50 2 C/W W Thermal Characteristics Symbol JA PD Description Maximum Thermal Resistance2 Maximum Power Dissipation2, 3 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on a FR4 board. 3. Derate 25mW/C above 25C. Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 3 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Electrical Characteristics1 VIN = 5V, VBOVP = 4.2V, V/EN = 0V , ROCP = 30k , TA = -40C to 85C unless otherwise noted. Typical values are at TA = 25C. Symbol VIN IQ Description Conditions Input Voltage Range Operation Quiescent Current IOUT = 0, ROCP = 30k Standby Current (Only UVLO and OVP ISTDBY circuit is "Enable", other function blocks EN = 5V, VOUT = 0 are all "Disable") VUVLO Under-Voltage Lockout Threshold Rising edge VUVLO_HYS Under-Voltage Lockout Hysteresis Deglitch Time, Input Power Detected Time measured from VIN 0V to 5V; TDGL Status 1s rise time to Output Turn ON Input OVP - Adjustable (AAT4685-1) ( Measured at OVP pin ) VOVP_TH Over-Voltage Lockout Threshold Rising Edge Over-Voltage Lockout Threshold VOVP_HYS Hysteresis Over-Voltage Lockout Threshold VOVP_RANGE Adjustable Range TRESP_OV Over-Voltage Response Time VOVP rise to 1.13V from 1.07V in 1ns Recovery Time From Input Over-Voltage TOVP_REC VOVP fall to 1.07V from 1.13V in 1ns Release Input OVP - Fixed (AAT4685-2 and AAT4685-3) ( Measured at IN pin ) Overvoltage Protection AAT4685-2 Rising Edge VOVPT Trip Voltage AAT4685-3 Over-Voltage Protection Trip Point VOVP_HYS Hysteresis TRESP_OV Over-Voltage Response Time VIN rise to 7.5V from 5V Recovery Time From Input Over-Voltage VIN fall to 5V from 7.5V TOVP_REC Release Input OCP IOCP Over-Current Range (Programmable) Rising Edge. ROCP = 30k IOCP/IOCP Over-Current Trip Tolerance Blanking Time, Input Over-Current TOCP_BL Detected Recovery Time From Input Over-Current TOCP_REC Condition Battery OVP ( Measured at BOVP pin ) Battery Over-Voltage Protection Trip Rising Edge VBOVPT Voltage Battery Over-Voltage Protection Trip VBOVP_HYS Point Hysteresis IBOVP Battery OVP Pin Input Current TBOVP_BL Battery OVP Pin Blanking Time Min Typ Max Units 600 28 800 V A 100 150 A 2.7 0.1 2.9 V V 3 2.5 8 0.97 1.0 ms 1.03 20 4 mV 7 V 1.0 s 8 6.60 5.71 6.80 5.85 ms 7.0 6.0 60 8 4.2 1.0 V V mV 1.0 0.3 0.9 V s ms 1.8 1.1 A A 180 s 64 ms 4.35 4.5 275 V mV 100 180 nA s 1. The AAT4685 is guaranteed to meet performance specification over the -40 to 85C operating temperature range and are assured by design, characterization and correlation with statistical process controls. 4 Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Electrical Characteristics1 VIN = 5V, VBOVP = 4.2V, V/EN = 0V , ROCP = 30k , TA = -40C to 85C unless otherwise noted. Typical values are at TA = 25C. Symbol Description OVP Switch On-Resistance RDS(ON) ID(OFF) Switch Off-Leakage Logic Control and Protection VEN(L) EN Input Low Voltage VEN(H) EN Input High Voltage IEN(H) EN Input Current VFLT FLT Output Low Voltage IFLT FLT Output Leakage VPOK POK Output Low Voltage IPOK POK Output Leakage TON OVP Switch Turn On Delay Time TSHDN Chip Thermal Shutdown Temperature Conditions Min ROCP = 16.5k, IOUT = 1200mA EN = 5V Typ Max Units 120 200 1 m A 0.4 V V A V A V A ms 1.2 VEN = 5.0V, Internal Pulldown = 200k IFLT = 4mA VIN = 0V, FLT = 5.5V IPOK = 4mA VIN = 0V, POK = 5.5V EN from 0V to 5V; ROUT = 10; COUT= 1F Threshold Hysteresis 25 0.4 1 0.4 1 8 140 15 C 1. The AAT4685 is guaranteed to meet performance specification over the -40 to 85C operating temperature range and are assured by design, characterization and correlation with statistical process controls. Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 5 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Typical Characteristics Operation Quiescent Current vs. Temperature Standby Current vs. Temperature 110 620 105 ISB (A) IQ (A) 610 600 590 100 95 90 580 -40 -15 10 35 60 85 -40 85 -15 Temperature (C) Operation Quiescent and Standby Current vs. Supply Voltage UVLO Threshold (V) Current (A) 60 85 2.80 IQ ISB 600 500 400 300 200 100 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 UVLO_Hi UVLO_Lo 2.75 2.70 2.65 2.60 2.55 -40 7.5 -15 Supply Voltage (V) 10 35 60 85 Temperature (C) AAT4685-1 Input OVP Threshold vs. Temperature Battery Over-Voltage Protection Trip Voltage vs. Temperature (VIN = 5.0V) 1.01 OVP_Rising OVP_Falling 4.50 Battery OVP_Thresh_hi Battery OVP_Thresh_low 4.45 1.00 4.40 VBOVPT (V) OVP Threshold (V) 35 Under-Voltage Lockout Threshold vs. Temperature 700 0 3.0 10 Temperature (C) 0.99 4.35 4.30 4.25 4.20 4.15 0.98 4.10 4.05 0.97 -40 -15 10 35 Temperature (C) 6 60 85 4.00 -40 -15 10 35 60 Temperature (C) Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 85 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Typical Characteristics EN VIH and VIL vs. Supply Voltage EN Pin vs. Temperature (VIN = 5.0V) 0.90 0.90 VIH VIL 0.85 0.80 VEN (V) 0.80 VEN (V) VIH VIL 0.85 0.75 0.75 0.70 0.70 0.65 0.65 0.60 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 0.60 -40 7.0 -15 10 35 60 85 Temperature (C) Supply Voltage (V) Over-Current Limit vs. ROCP NMOS On-Resistance vs. Temperature 2.25 155 2.00 1.75 RDS(ON) (m) 140 IOCP (A) 1.50 1.25 1.00 0.75 125 110 0.50 0.25 0.00 10 100 95 -40 -15 10 ROCP (k) 35 60 85 Temperature (C) Normal Power-On Startup Over-Current Protection (ROUT = 6.3) (IOUT switches from 0.8A to 1.5A, ILIM = 1A) VIN (5V/div) VOUT (2V/div) VIN (2V/div) 5V IOUT (500mA/div) VOUT (2V/div) FLT (5V/div) IOUT (500mA/div) Time (2ms/div) Time (50s/div) Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 7 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Typical Characteristics Over-Voltage Protection Response for Input Step Recovery from Over-Voltage Protection (VIN = 7V to 5V) (VIN = 5V to 12V) VIN (2V/div) VIN (2V/div) VOUT (2V/div) IOUT (500mA/div) VOUT (2V/div) FLT (5V/div) FLT (5V/div) Time (20s/div) Time (2ms/div) Battery Over-Voltage Protection Recovery from Battery Over-Voltage Protection (VBOVP steps from 3.8V to 4.5V) (VBOVP = 4.5V to 3.8V) VBOVP (1V/div) VOUT (2V/div) VBOVP (1V/div) IOUT (500mA/div) VOUT (2V/div) IOUT (500mA/div) FLT (5V/div) FLT (5V/div) Time (100s/div) Time (500s/div) Battery Over-Voltage Protection Power-up into Short Circuit on the OUT Pin (VBOVP Cycles Between 4V and 4.5V) VBOVP (2V/div) VIN (5V/div) VOUT (2V/div) IOUT (500mA/div) VOUT (5V/div) FLT (5V/div) FLT (5V/div) Time (20ms/div) 8 Time (200ms/div) Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Functional Block Diagram OVP Switch OUT IN UVLO OVP POK OCP CP Driver VREF POK Detect INT _VP INT Regulator FLT INT _VP POR Bias VREF and BG INT _VP BOVP OCP Control and Timer INT _VP VREF EN OTP option Functional Description The AAT4685 provides up to 28V over-voltage and overcurrent protection when powering low-voltage systems such as cell phones, MP3, and PDAs or when charging Lithium Ion batteries from a badly regulated supply. The AAT4685 is inserted between the power supply or charger source and the load to be protected. The AAT4685 IC consists of a low resistance OVP switch, under-voltage lockout protection, over-voltage monitor and protection, over-current protection, battery over-voltage protection, fast shut-down circuitry and a fault output flag. In normal operation the OVP switch acts as a slew-rate controlled load switch, connecting and disconnecting the power supply from IN to OUT. A low resistance N channel MOSFET is used as to minimize the voltage drop between the voltage source and the load and to reduce the power dissipation. When the voltage on the input exceeds the programmed over-voltage trip point, the device immediately turns off GND the internal OVP switch disconnecting the load from the abnormal voltage, preventing damage to any downstream components. In the case of an over current condition, it limits the system current at the threshold value, and if the over current persists, the OVP switch is turned off after a blanking period. If the battery voltage rises to an unsafe level (BOVP threshold), the IC disconnects OUT from the charging input power IN until the battery voltage returns to an acceptable value. BOVP or OCP blanking time ignores short time transients of over-battery voltage and overload current. Additionally, AAT4685 also monitors its own die temperature and turns the OVP switch off if it becomes too hot. The AAT4685 has a fault flag (FLT) pin to indicate the fault conditions of input power over-voltage, load current over-current, battery over-voltage, and over-temperature by pulling the flag signal down to alert the system. If an input over-voltage condition or over-voltage battery condition exists at the time of the device enable, then the OVP switch will remain OFF and FLT is always low. Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 9 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Under-Voltage Lockout (UVLO) The AAT4685 has a fixed 2.7V under-voltage lockout level (UVLO) trip level for IN rising. When the input voltage is less than 2.7V - VUVLO_HYS, the OVP switch is turned off. 100mV of hysteresis is included to ensure circuit stability. Over-Voltage Protection (OVP) The AAT4685 adjustable version has a 1.0V 3% overvoltage trip threshold on the OVP pin. With a resistor divider on OVP pin from IN to GND, the over-voltage protection point of IN can be adjusted between 4V and 7V. If the over-voltage trip level is triggered, the OVP switch will start to be turned off in 1s. The FLT pin is driven low. When the input voltage pin returns below VOVPT - VOVP_HYS (but is still above VUVLO), the OVP switch is turned on again after a TOVP_REC recovery time to ensure that the input supply has stabilized. Fixed OVP products are also available where the resistive divider is internally integrated. Pin 12 is designed to be not connected. Over-Current Protection (OCP) The AAT4685 integrates adjustable over-current protection. Once the load current exceeds the pre-set limit of IOCP current (ILOAD>IOCP), the load current is limited after the OCP blanking time (typical 180s). During the OCP blanking time, the OVP switch stays ON. Once the load current drops below IOCP, current restriction will be removed. If the over-current state continues after the blanking period, the OVP switch turns off and FLT is pulled down. In order to prevent the input voltage from spiking up due to the inductance of the input cable, the OVP switch is turned off slowly, resulting in a "soft-stop." The OVP switch will turn back on again after TOCP_REC (typical 64ms) and the current is monitored all over again. Each time an OCP fault occurs, an internal counter is incremented. If 15 OCP faults occur in one charge cycle, the OVP switch is turned off permanently. The counter is cleared either by removing and re-applying input power, or by disabling and re-enabling the device via the EN pin. 10 The OCP threshold is set by an external resistor (ROCP) connected between OCP and ground. IOCP is approximated by the following formula: IOCP = 30 (current in A, resistance in k) ROCP Battery Over-Voltage Protection (BOVP) The AAT4685 monitors the positive battery terminal and turns the OVP switch off when the battery voltage exceeds the BOVP threshold (typical 4.35V). The monitor has blanking time TBOVP_BL (typical 180s) to prevent any transient voltage from false triggering the BOVP. A resistor is required between the BOVP pin and the battery, to limit the current in case of a short circuit condition. If the battery voltage exceeds the BOVP trip threshold VBOVPT, the OVP switch is turned off, and the FLT pin is driven low. In order to prevent the input voltage from spiking up due to the inductance of the input cable, the OVP switch is turned off slowly , resulting in a "soft-stop." The OVP switch is turned back on once the battery voltage drops to VBOVPT - VBOVP_HYS. Each time a battery overvoltage fault occurs, an internal counter is incremented. If 15 such faults occur in one charge cycle, the OVP switch is turned off permanently. The counter is cleared either by removing and re-applying input power, or by disabling and re-enabling the device via the EN pin. Over-Temperature Protection (OT Protection) If the junction temperature of the device exceeds TSHDN, the OVP switch is turned off, and the FLT pin is driven low. The OVP switch is turned back on when the junction temperature falls below TSHDN - 15C. Fault Indicator (FLT) The FLT output is an active-low open-drain fault (OV/OC/ BOVP/OT) reporting output. A pull-up resistor should be connected from FLT to the logic I/O voltage of the host system. When EN is low, FLT is asserted by pulling down in the case of an over-voltage, over-current, or battery over-voltage or over-temperature fault occuring; FLT is de-asserted into high impedance state with the fault removed. When EN is high, FLT is in high impedance status. Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Enable Control (EN) Device Start-Up Operation EN is an active low enable with internal 200k resistor pulled down to GND. EN is driven low, connected to ground, or left floating for normal device operation. Set EN low to turn the OVP switch on after turn on delay time. Set EN high to turn the OVP switch off. In the case of an over-voltage or UVLO condition toggling EN will not override the fault condition and the OVP switch will remain off. The OCP counter and the BOVP counter are both reset when the device is re-enabled by the EN pin. On initial power-up, if VUVLO < IN < VOVP, VBAT < VBOVP, and EN is low, the OVP switch starts to turn on after TON delay time (typical 8ms) to be stabilized for input. This turn on uses Soft Start to control the inrush current to minimize ringing at the input. Because of the deglitch time at power on, if the input voltage rises rapidly past the OVP threshold, the device does not switch on at all; instead it goes into protection mode and indicate a fault on the FLT pin. After successful start-up, if ILOAD > IOCP limit the device turns off and the fault flag is asserted. IC Input Internally connected to GND through a 100k resistor. Connect this pin to ground. The Soft Start function is defined as follows: "current limit is stepped digitally from low level to its final current limit level for soft starting." Power-OK Indicator (POK) The AAT4685 contains an open-drain POK output that goes low when a valid input source is detected at the IN pin. The valid input range is between VUVLO (typical 2.7V) and VOVP voltage (fixed 5.85V / fixed 6.8V / adjustable OVP threshold set by external resistors). After a valid input has been established, charging is sustained. The POK function is always active whether the EN pin is at low or high state. Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 11 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP System Flowchart Power ON Any State : If V(IN) < UVLO go to "Power ON" If EN = H go to "Standby" N EN = L All functions OFF Y Reset : Timers reset Counters reset FLT = HiZ UVLO : ON N V(IN) > UVLO BOVP, TSD : ON Y OVP : ON N FLT=HiZ Y Standby Wait t DGL (8ms) OCP : ON Turn On OVP switch, FLT = HiZ FLT state VIN > OVP Y Turn Off OVP swtch, FLT = L V(IN) < OVP N Y Wait tOVP_REC (8ms) N FLT state VBAT > BOVP Y Blanking Time 180s N Y Turn Off OVP switch, FLT = L, Incr BOVP counter count <15 ? N Y VBAT < BOVP N EN = H Y N Y Goto Standby N FLT state I > IOCP Y Limit Current Blanking Time 180s Turn Off OVP switch, FLT = L, Incr OCP counter Y Y Wait t OCP_REC (64ms) Y Goto Standby N N N count <15 ? EN = H N FLT state TJ > TSHDN N 12 Y Turn Off OVP swtch, FLT = HiZ TJ < TSHDN -15 Y N Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Application Information Table 2 summarizes 1% standard metal film resistors for several over-current settings. Over-Voltage Protection Resistors The over-voltage protection threshold is programmed with two resistors, R1 and R2. To limit the current going through the external resistor string while maintaining good noise immunity, use smaller resistor values, such as 10k for R2. Using a larger value will further reduce the system current, but will also increase the impedance of the OVP node, making it more sensitive to external noise and interference. A suggested value for R2 is 100k. R1 can be calculated using the following equation: R1 = VOVP - 1 * R2 = (VOVP - 1) * 100 VOVP_TH Table 1 summarizes 1% standard metal film resistors for several over-voltage settings. R2 (k) R1 (k) VOVP Setting (V) 100 100 100 100 100 100 100 300 348 402 442 499 549 604 4.0 4.5 5.0 5.5 6.0 6.5 7.0 Table 1: 1% Standard Resistor Values for OVP Setting. Over-Current Protection Resistor The over-current threshold is programmed by an external resistor (ROCP) connected from the OCP pin to GND. ROCP can be calculated by the following equation. ROCP = 30 * 1000 IOCP R3 (k) IOCP Setting (A) 100.0 86.6 75.0 66.5 60.4 54.9 49.9 43.0 37.4 33.2 30.1 24.9 21.5 18.7 16.5 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.70 0.80 0.90 1.00 1.20 1.40 1.60 1.80 Table 2: 1% Standard Resistor Values for OCP Setting. Input Capacitor A 1F or larger capacitor is typically recommended for CIN. CIN should be located as close to the device IN pin as practically possible. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor equivalent series resistance (ESR) requirement for CIN. However, for higher current operation, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. Capacitors are typically manufactured in different voltage ratings. If the maximum possible surge voltage is known, select capacitors with a voltage rating at least 5V higher than the maximum possible surge voltage. 50V rated capacitors are generally good for most OVP applications to prevent any surge voltage. Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 13 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Output Capacitor PCB Layout Recommendations In order to insure stability while current limit is active, a small output capacitance of approximately 1F is required at the output. Likewise, with the output capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be increased to accommodate any load transient condition. For proper thermal management and to take advantage of the low RDS (ON) of the AAT4685, certain circuit board layout rules should be followed: 1. VIN and VOUT should be routed using wider than normal traces. 2. GND should be connected to a ground plane. The ground plane area connected to the ground pins should be made as large as possible. Exposed pad should be connected to ground plane to get best power dissipation. 3. For best performance, CIN and COUT should be placed close to the IN and OUT pins. Evaluation Board Schematic +5V Red LED 7 VIN R1 604k 1 2 +5V Disable 8 C1 R2 1F 100k IN OUT 6 OUT 5 11 12 OVP BOVP 1 OCP POK EN FLT 10 IC GND 9 3 R3 30k U1 AAT4685 IN R5 1.74k 2 Green LED R6 1.74k VOUT BATT R4 100k 4 C2 1F Figure 1: AAT4685 Evaluation Board Schematic. 14 Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Evaluation Board Layout Figure 2: AAT4685 Evaluation Board Top Side Layout. Figure 3: AAT4685 Evaluation Board Bottom Side Layout. Evaluation Board Bill of Materials Designator Part Number Description Manufacturer U1 C1, C2 R1 R3 R2, R4 R5, R6 LED1 LED2 AAT4685IWP-1-T1 GRM21BR71H105K RC0603FR-07604KL RC0603FR-0730K1L RC0603FR-07100KL RC0603FR-071K74RL 0805KRCT 0805KGCT IC Over-Voltage Protection Switch with OCP Cap Ceramic 1F 0805 X7R 50V 10% Res 604k 1/10W 1% 0603 SMD Res 30.1K 1/10W 1% 0603 SMD Res 100K 1/10W 1% 0603 SMD Res 1.74k 1/10W 1% 0603 SMD LED Red 0805 LED Green 0805 Skyworks Murata Yageo HB Table 3: AAT4685 Evaluation Board Bill of Materials (BOM). Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 15 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Ordering Information Package OVP Trip Voltage Marking1 Part Number (Tape and Reel)2 TDFN33-12 TDFN33-12 TDFN33-12 Adjustable 6.80V 5.85V 8LXYY AAT4685IWP-1-T1 AAT4685IWP-2-T1 AAT4685IWP-3-T1 Skyworks GreenTM products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of GreenTM, document number SQ04-0074. Packaging Information TDFN33-12 Index Area 0.40 0.05 Detail "A" C0.3 0.45 0.05 2.40 0.05 3.00 0.05 0.1 REF 3.00 0.05 1.70 0.05 Top View Bottom View 0.23 0.05 Pin 1 Indicator (optional) 0.05 0.05 0.23 0.05 0.75 0.05 Detail "A" Side View All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. 16 Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 DATA SHEET AAT4685 Over-Voltage Protection Switch with OCP and BOVP Copyright (c) 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. ("Skyworks") products or services. 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Skyworks Solutions, Inc. * Phone [781] 376-3000 * Fax [781] 376-3100 * sales@skyworksinc.com * www.skyworksinc.com 201960A * Skyworks Proprietary Information * Products and Product Information are Subject to Change Without Notice. * May 16, 2012 17