Step-Down DC/DC Controller TLE 6389 Target Datasheet Features * * * * * * * * * * * * Operation from 5V to 60V Input Voltage 100% Maximum Duty Cycle Efficiency >90% Output Current up to 3A Less than 100A Quiescent Current 2A Max Shutdown Current Up to 350kHz Switching Frequency Adjustable and Fixed 5V and VIN 3.3V Output Voltage versions 3% output voltage accuracy (PWM Mode) Current-Mode Control Scheme On Chip Low Battery Detector Ambient operation range -40C to 125C R = P-DSO-14-3, -4, -9, -11 RSENSE= 0.05 L1 = 47 H M1 VOUT IOUT CIN1 = 100 F CBDS= COUT = D1 100 F 220 nF 11 13 CIN2 = 220nF SI1 400k 14 BDS 12 2 GDRV CS VS 7 RSI2= TLE6389G50-1 SI SI_GND SI_ENABLE 100k 1 6 ON SYNC GND 5 OFF 3 FB VOUT 9 SO 10 RO M1: Infineon SPD09P06PL D1: Motorola MBRD360 L1: Coilcraft DO3340P-473 Cin1: TBD Cout: Low ESR Tantalum RD 4 8 CRD =100nF Type Ordering Code Package Description TLE 6389 GV on request P-DSO-14 adjustable TLE 6389 G50 on request P-DSO-14 5V, Device Enable TLE 6389 G50-1 on request P-DSO-14 5V, SI GND, SI Enable TLE 6389 G33 on request P-DSO-14 3.3V, Device Enable TLE 6389 G33-1 on request P-DSO-14 3.3V, SI GND, SI Enable Functional description The TLE6389 step-down DC-DC switching controllers provide high efficiency over loads ranging from 1mA up to 3A. A unique PWM/PFM control scheme operates with up to a 100% duty cycle, resulting in very low dropout voltage. This control scheme eliminates minimum load requirements and reduces the supply current under light loads to 100A. These step-down controllers drive an external P-channel MOSFET, allowing design flexibility for applications up to 3A. A high switching frequency (up to 350kHz) and Target Datasheet Rev. 1.7 1 2001-09-17 TLE 6389 operation in continuous-conduction mode allow the use of tiny surface-mount inductors. Output capacitor requirements are also reduced, minimizing PC board area and system costs. The output voltage is preset at 5V (TLE6389-50) or 3.3V (TLE6389-33) and adjustable for the TLE6389. Input voltages can be up to 60V. Pin Configuration (top view) ENABLE / 1 SI_EN 14 CS FB 2 13 VS 12 GDRV VOUT 3 GND 4 P-D-SO-14 11 BDS SYNC 5 10 RO SI_GND 6 9 SO SI 7 8 RD Pin Definitions and Functions Pin No SO-14 Symbol Function 2 FB Feedback Input. 1. For adjustable-output operation connect to an external voltage divider between the output and GND (see the Setting the Output Voltage section). 2. Sense input for fixed 5V or 3.3V output operation. FB is internally connected to an on-chip voltage divider. 3 VOUT VOUT Input. Input for internal supply. Connect to output if variable version is used. For fixed voltage version connect FB and VOUT. 1 ENABLE Active-Low Enable Input. Device is placed in shutdown when Enable is driven low. In shutdown mode, the reference, output, and external MOSFET are turned off. Connect to logic high for normal operation. (TLE6389G50, TLE6389G33, TLE6389GV only) Target Datasheet Rev. 1.7 2 2001-09-17 TLE 6389 Pin No SO-14 Symbol Function 1 SI_ENA BLE SI Enable Input. SI_GND is switched to high impedance when SI_Enable is low. High level at SI_Enable connects SI_GND to GND via a low impedance path. SO is undefined when SI_Enable is low. (TLE6389G501, TLE6389G33-1 only) 13 VS Supply Input. Bypass with 0.47F. 4 GND Ground. Analog signal ground. 6 SI_GND SI Ground. Ground connection for SI comparator resistor devider. 11 BDS Buck Driver Supply Input. Connect ceramic capacitor between BDS and VS to generate clamped gate-source voltage to drive the PMOS power stage. 14 CS Current-Sense Input. Connect current-sense resistor between VS and CS. External MOSFET is turned off when the voltage across the resistor equals the current-limit trip level. 12 GDRV Gate Drive Output for External P-Channel MOSFET. GDRV swings between VS and BDS. 10 RO Reset Output. Open drain output from reset comparator with an internal pull up resistor. 8 RD Reset Delay. Connect a capacitor to ground for delay time adjustment. 9 SO Sense Output Comparator. Open drain output from SI comparator with an internal pull up resistor. 7 SI Sense Input Comparator. Input to the Low-Battery Comparator. This input is compared to an internal 1.25V reference. 5 SYNC Input for external synchronization. An external clock signal connected to this pin allows for GDRV switching synchronization. Target Datasheet Rev. 1.7 3 2001-09-17 TLE 6389 1 Item Absolute Maximum Ratings Parameter Symbol Limit Values Unit min. max. Remarks Supply Input 1.0.1 Voltage VS -0.3 60 V 1.0.2 Current IS - - - - Current Sense Input 1.0.3 Voltage VCS -0.3 60 V 1.0.4 Current ICS - - - - Gate Drive Output 1.0.5 Voltage VGDRV - 0.3 6.8 V |VS - VGDRV|<6.8V 1.0.6 Current IGDRV - - - Internally limited |VS - VBDS|<6.8V Buck Drive Supply Input 1.0.7 Voltage VBDS - 0.3 55 V 1.0.8 Current IBDS - - - Feedback Input 1.0.9 Voltage VFB - 0.3 6.8 V 1.0.10 Current IFB - - - 6.8 V - - SI_Enable Input 1.0.11 Voltage VSI_ENAB - 0.3 LE 1.0.12 Current ISI_ENABL - (TLE6389G50-1, TLE6389G33-1 only) E SI_GND Input 1.0.13 Voltage VSI_GND - 0.3 60 V 1.0.14 Current ISI_GND - - - (TLE6389G50-1, TLE6389G33-1 only) Enable Input Target Datasheet Rev. 1.7 4 2001-09-17 TLE 6389 1 Item Absolute Maximum Ratings (cont'd) Parameter Symbol Limit Values Unit min. max. 1.0.15 Voltage VENABLE - 0.3 60 V 1.0.16 Current IENABLE - - - Remarks (TLE6389G50, TLE6389G33, TLE6389GV only) Sense Input 1.0.17 Voltage VSI - 0.3 60 V 1.0.18 Current ISI - - - Sense Output 1.0.19 Voltage VSO - 0.3 6.8 V 1.0.20 Current ISO - - - VOUT Input 1.0.21 Voltage VOUT - 0.3 15 V 1.0.22 Current IOUT - - - Reset Delay Adjust Input 1.0.23 Voltage VRD - 0.3 6.8 V 1.0.24 Current IRD TBD TBD mA Reset Output 1.0.25 Voltage VRO - 0.3 6.8 V 1.0.26 Current IRO -2 2 mA Synchronization Input 1.0.27 Voltage VSYNC - 0.3 6.8 V 1.0.28 Current ISYNC TBD TBD mA ESD-Protection (Human Body Model; R=1,5k; C=100pF) 1.0.29 all pins to GND Target Datasheet Rev. 1.7 VHBM -2 5 2 kV 2001-09-17 TLE 6389 1 Item Absolute Maximum Ratings (cont'd) Parameter Symbol Limit Values Unit Remarks min. max. - 40 150 C - - 50 150 C - Temperatures 1.0.30 Junction temperature 1.0.31 Storage temperature Tj Tstg Note: Maximum ratings are absolute ratings; exceeding any one of these values may cause irreversible damage to the integrated circuit. Target Datasheet Rev. 1.7 6 2001-09-17 TLE 6389 2 Item Operating Range Parameter Symbol Limit Values min. max. Unit Remarks 2.0.1 Supply voltage range VS 5 48 V 2.0.2 Junction temperature Tj - 40 150 C 180 K/W - TBD K/W - Thermal Resistance 2.0.3 Junction ambient 2.0.4 Junction pin 3 Rthj-a Rthj-p Electrical Characteristics 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values Unit Test Condition min. typ. max. Current Consumption1) TLE6389 (variable) 3.0.1 Supply current into VS IS 80 A VS = 13.5 V; VENABLE = 5 V; IOUT = 0 mA; TJ = 25 C; 3.0.2 110 A VS = 42 V; VENABLE = 5 V; IOUT = 0 mA; TJ = 25 C; 3.0.3 3.0.4 FB current IFB 2 A VENABLE=0V 4 A VENABLE = 5 V; TJ = 25 C; Target Datasheet Rev. 1.7 7 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values min. typ. Unit Test Condition max. Current Consumption TLE6389-50 3.0.5 Supply current into VS IS 50 A VS = 13.5 V; VENABLE = 5 V; IOUT = 0 mA; TJ = 25 C; 3.0.6 80 A VS = 42 V; VENABLE = 5 V; IOUT = 0 mA; TJ = 25 C; 3.0.7 3.0.8 FB current IFB 2 A VENABLE=0V 50 A VENABLE = 5 V; VOUT = 5 V; TJ = 25 C; Current Consumption TLE6389-33 3.0.9 Supply current into VS 80 IS A VS = 13.5 V; VENABLE = 5 V; IOUT = 0 mA; TJ = 25 C; 3.0.10 110 A VS = 42 V; VENABLE = 5 V; IOUT = 0 mA; TJ = 25 C; 3.0.11 2 A VENABLE=0V Current Consumption TLE6389-50-1 Target Datasheet Rev. 1.7 8 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values Unit Test Condition min. typ. max. 3.0.12 Supply current into VS IS 50 A VS = 13.5 V; IOUT = 0 mA; TJ = 25 C; 3.0.13 80 A VS = 42 V; IOUT = 0 mA; TJ = 25 C; 3.0.14 FB current IFB 50 A VOUT = 5 V; TJ = 25 C; Current Consumption TLE6389-33-1 3.0.15 Supply current into VS 80 IS A VS = 13.5 V; IOUT = 0 mA; TJ = 25 C; 3.0.16 110 A VS = 42 V; IOUT = 0 mA; TJ = 25 C; 3.0.17 FB current 15 IFB A VOUT = 3.3 V; TJ = 25 C; Buck-Controller 3.0.18 Output voltage Target Datasheet Rev. 1.7 VOUT 4.85 5 9 5.15 V 5V Versions; VS = 5.8 V to 48V; IOUT = TBDmA to 2A (PWM Mode); RSENSE = 0.05; RM1 = 0.25;RL1 = 0.1; 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter 3.0.19 Output voltage Symbol VOUT 3.0.20 3.0.21 Output voltage 3.0.24 Output adjust range min. typ. max. 4.75 5 5.25 3.8 VOUT 3.0.22 3.0.23 FB threshold voltage Limit Values VFB,th Unit Test Condition V 5V Versions; VS = 5.8 V to 48V; IOUT = 0mA to TBDA (PFM Mode); RSENSE = 0.05; RM1 = 0.25;RL1 = 0.1; V 5V Versions; VS = 4.2 V to 5.8V; IOUT = 0mA to 500mA; RSENSE = 0.1; RM1 = 0.4;RL1 = 0.1; -3% 3.3 +3% V 3.3V Versions; VS = 5 V to 48V; IOUT = TBD to 2A (PWM Mode); -5% 3.3 +5% V 3.3V Versions; VS = 5 V to 48V; IOUT = 0mA to TBD (PFM Mode); 1.22 1.25 1.27 5 5 V TLE6389GV 5 15 V TLE6389GV 3.0.25 Line regulation 0.7 1 mV/ V TBD 3.0.26 Load regulation 20 30 mV/ A IOUT = 5mA to 2A; 0.2 V VENABLE = 5 V CBDS = 220 nF CGDRV = 5nF 3.0.27 Gate driver, P-gate to source voltage (off) Target Datasheet Rev. 1.7 VGDRV - 0 VS 10 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values Unit Test Condition min. typ. max. 3.0.28 Gate driver, P-gate to source voltage (on) VGDRV - TBD VS 3.0.29 Gate driver, peak charging current IGDRV TBD A 3.0.30 Gate driver, peak discharging current IGDRV TBD A 3.0.31 Gate driver, rise time tr 70 ns 3.0.32 Gate driver, fall time tf 100 ns 3.0.33 Gate driver, gate charge QGDRV 50 3.0.34 Current Limit Threshold Voltage VLIM = VVS - VCS 70 3.0.35 PWM to PFM Threshold Current 3.0.36 PFM to PWM Threshold Timing toff_PFM 3.0.37 Oscillator frequency fOSC 270 3.0.38 Maximum duty cycle dMAX 100 6.5 Target Datasheet Rev. 1.7 270 11 VENABLE = 5 V CBDS = 220 nF CGDRV = 5nF VENABLE = 5 V CBDS = 220 nF CGDRV = 5nF VENABLE = 5 V CBDS = 220 nF CGDRV = 5nF nC 100 130 mV 0.1* ILIM mA TBD s 360 3.0.39 Minimum duty cycle dMIN 3.0.40 SYNC capture range V 360 450 ILIM = VLIM / RSENSE kHz PWM mode only % PWM mode only TBD % PWM mode only 450 PWM mode only kHz 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values min. typ. Unit Test Condition max. Reset Generator 3.0.41 Reset threshold VRT 0.9* 1.25 V TLE6389GV only; VOUT decreasing 3.0.42 Reset threshold hysteresis VRT,hys 100 mV TLE6389GV only 3.0.43 Reset threshold VRT 3.5 3.65 3.8 V 5V Versions; VOUT decreasing 4.5 4.65 4.8 V 5V Versions; VOUT increasing 2.8 2.95 3.1 V 3.3V Versions; VOUT decreasing 2.9 3.05 3.2 V 3.3V Versions; VOUT increasing 10 20 k 3.3V and 5V Versions; Internally connected to 3.0.44 3.0.45 Reset threshold VRT 3.0.46 3.0.47 Reset pull up RRO 40 VOUT 3.0.48 Reset output High voltage VROH 3.0.49 Reset output Low voltage VROL 0.8* V 3.3V and 5V Versions;IROH=0 mA V IROL=1mA; 2.5V < VOUT < VOUT 0.2 0.4 VRT 3.0.50 3.0.51 Reset delay charging current Target Datasheet Rev. 1.7 0.2 4 Id 12 0.4 V IROL=0.2mA; 1V < VOUT < 2.5V A VD = 1V 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values Unit Test Condition min. typ. max. 3.0.52 Upper reset timing threshold VRDO tbd V -- 3.0.53 Lower timing threshold VRDL tbd V -- 3.0.54 Reset delay time td 70 ms CRD = 100nF 3.0.55 Reset reaction time trr 10 s 3.0.56 Reset Output delay tROd 1 s CRD = 100nF CRD = 100nF 35 50 ENABLE Input 3.0.57 Enable ONthreshold VENABLE, 2 3.0.58 Enable OFFthreshold VENABLE, V ON 0.8 V 5 A 2 A OFF 3.0.59 H-level input current IENABLE,O N 3.0.60 L-level input current IENABLE,O FF SI_ENABLE Input 3.0.61 Enable ONthreshold 3.0.62 Enable OFFthreshold VENABLE, 2 V ON VENABLE, 0.8 V 5 A OFF 3.0.63 H-level input current IENABLE,O N Target Datasheet Rev. 1.7 13 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values min. typ. 3.0.64 L-level input current IENABLE,O Unit Test Condition max. 2 A FF SI_GND Input 3.0.65 Switch ON resistance RSW 100 Tj=25C; ISI_GND = TBDuA Battery Voltage Sense 3.0.66 Sense threshold high to low Vsi, high 1.13 1.25 1.37 V 3.0.67 Sense threshold hysteresis Vsi, hys - 100 - mV - 3.0.68 S ense out pull up RSO 10 20 40 k 3.3V and 5V Versions; Internally connected to VOUT 3.0.69 Sense out output High voltage VSOH 3.0.70 Sense out output Low voltage VSOL 0.8* ISOH =0mA VOUT 3.0.71 3.0.72 Sense input current V ISI -1 0.2 0.4 V ISOL=1mA; 2.5V < VOUT; VSI < 1.13 V 0.2 0.4 V ISOL=0.2mA; 1V <VOUT <2.5V; VSI < 1.13 V 0.1 1 A - Thermal Shutdown Target Datasheet Rev. 1.7 14 2001-09-17 TLE 6389 3 Electrical Characteristics (cont'd) 5V< VS <48V; - 40C< Tj <150C; all voltages with respect to ground; positive current defined flowing into the pin; unless otherwise specified Item Parameter Symbol Limit Values Unit Test Condition min. typ. max. 3.0.73 Thermal shutdown junction temperature TjSD 3.0.74 Temperature hysteresis DT 1) 150 175 30 200 C K The device IS and IFB current measurements exclude MOSFET driver currents. Contribution of MOSFET driver currents are discussed in application section. Target Datasheet Rev. 1.7 15 2001-09-17 TLE 6389 4 Detailed Description The TLE6389 family is a family of step-down DC-DC controllers designed primarily for use in high voltage applications such as automotive. Using an external MOSFET and current-sense resistor allows design flexibility and the improved efficiencies associated with high-performance P-channel MOSFETs. A unique, current-limited, pulse-width (PWM)/pulse-frequency-modulated (PFM) control scheme gives these devices excellent efficiency over load ranges up to three decades, while drawing less than 100A under no load. This wide dynamic range optimizes the TLE6389 for automotive applications, where load currents can vary considerably as individual circuit blocks are turned on and off to conserve energy. Operation to a 100% duty cycle allows the lowest possible dropout voltage, allowing operation during cold cranking. High switching frequencies and a simple circuit topology minimize PC board area and component costs. The output voltage is sensed either by an internal voltage divider connected to the FB pin (TLE6389-50 and TLE6389-33) or an external divider returned to the FB pin (TLE6389). RSENSE= 0.05 VIN L1 = 47 H M1 VOUT IOUT CIN1 = 100 F CBDS= COUT = D1 100 F 220 nF 11 13 RSI1= 400k CIN2 = 220nF RSI2= 100k 14 CS BDS 12 2 GDRV 3 FB VOUT 9 SO 10 RO VS 7 TLE6389G50 SI SI_GND ENABLE 6 SYNC 1 ON 5 GND 4 M1: Infineon SPD09P06PL D1: Motorola MBRD360 L1: Coilcraft DO3340P-473 Cin1: TBD Cout: Low ESR Tantalum RD 8 CRD =100nF OFF TLE6389G50 Application Circuit Target Datasheet Rev. 1.7 16 2001-09-17 TLE 6389 RSENSE= 0.05 VIN CIN1 = 100 F L1 = 47 H M1 CBDS= RSO= 20k D1 220 nF 11 13 RSI1= 400k CIN2 = 220nF 12 VOUT SO 9 TLE6389GV RO 10 100 F RFB1= TBDk FB 2 SI_GND ENABLE 100k COUT = RRO= 20k 3 GDRV CS SI 7 RSI2= 14 BDS VS VOUT 6 SYNC GND 5 1 ON RFB2= RD 4 47k 8 OFF CRD =100nF M1: Infineon SPD09P06PL D1: Motorola MBRD340 L1: Coilcraft DO3340P-473 Cin1: TBD Cout: Low ESR Tantalum TLE6389GV Application Circuit RSENSE= 0.05 VIN L1 = 47 H M1 VOUT IOUT CIN1 = 100 F CBDS= COUT = D1 100 F 220 nF 11 13 RSI1= 400k CIN2 = 220nF RSI2= 14 CS BDS 2 VS 7 TLE6389G50-1 SI SI_GND SI_ENABLE 100k 12 GDRV 6 SYNC GND 1 ON 5 4 3 FB VOUT 9 SO 10 RO M1: Infineon SPD09P06PL D1: Motorola MBRD360 L1: Coilcraft DO3340P-473 Cin1: TBD Cout: Low ESR Tantalum RD 8 CRD =100nF OFF TLE6389G50-1 Application Circuit Target Datasheet Rev. 1.7 17 2001-09-17 TLE 6389 4.1 Operating Modes 4.1.1 PWM Control Scheme The TLE6389 uses a slope-compensated, current-mode PWM controller capable of achieving 100% duty cycle. The device uses an oscillator-triggered, minimum on-time, current-mode control scheme. The minimum on-time is approximately 200ns unless in dropout. The maximum on-time is greater than 1/fOSC, allowing operation to 100% duty cycle. Current-mode feedback provides cycle-by-cycle current limiting for superior loadand line-response and protection of the external MOSFET and rectifier diode. At each falling edge of the internal oscillator, the oscillator cell sends a PWM ON signal to the control and drive logic, turning on the external P-channel MOSFET. This allows current to ramp up through the inductor to the load, and stores energy in a magnetic field. The switch remains on until either the current-limit comparator is tripped or the PWM comparator signals that the output is in regulation. When the switch turns off during the second half of each cycle, the inductor's magnetic field collapses, releasing the stored energy and forcing current through the rectifier diode to the output-filter capacitor and load. The output-filter capacitor stores charge when the inductor current is high and releases it when the inductor current is low, thus smoothing the voltage across the load. During normal operation, the TLE6389 regulates output voltage by switching at a constant frequency and then modulating the power transferred to the load each cycle using the PWM comparator. A multi-input comparator sums three weighted differential signals: the output voltage with respect to the reference, the main switch current sense, and the slope-compensation ramp. It modulates output power by adjusting the inductorpeak current during the first half of each cycle, based on the output-error voltage. 4.1.2 100% Duty-Cycle Operation and Dropout The TLE6389 operates with a duty cycle up to 100%. This feature extends allows to operate with the lowest possible drop at low battery voltage as it occurs at cold ambient temperatures. The MOSFET is turned on continuously when the supply voltage approaches the output voltage. This services the load when conventional switching regulators with less than 100% duty cycle would fail. Dropout voltage is defined as the difference between the input and output voltages when the input is low enough for the output to drop out of regulation. Dropout depends on the MOSFET drain-to-source onresistance, current-sense resistor, and inductor series resistance, and is proportional to the load current: Dropout Voltage = IOUT x (RDS(ON) + RSENSE + RINDUCTOR) Target Datasheet Rev. 1.7 18 2001-09-17 TLE 6389 4.1.3 PWM/PFM Operation This control scheme overrides PWM mode and places the TLE6389 in PFM mode at light loads to improve efficiency and reduce quiescent current to less than 100A. The pulse-skipping PFM operation is initiated when the peak inductor current drops below 0.1 x Ilimit. During PFM operation, the TLE6389 switches only as needed to service the load, reducing the switching frequency and associated losses in the external switch, the rectifier diode, and the external inductor. During PFM mode, a switching cycle initiates when the PFM comparator senses that the output voltage has dropped too low. The Pchannel MOSFET switch turns on and conducts current to the output-filter capacitor and load until the inductor current reaches the PFM peak voltage limit. Then the switch turns off and the magnetic field in the inductor collapses, forcing current through the synchronous rectifier to the output filter capacitor and load. Then the TLE6389 waits until the PFM comparator senses a low output voltage again. Output ripple is higher during PFM operation. A larger output-filter capacitor can be used to minimize ripple. 4.2 SYNC Input and Frequency Control The TLE6389's internal oscillator is set for a fixed-switching frequency of 360kHz or can be synchronized to an external clock. Do not leave SYNC unconnected. Connecting SYNC to GND enables PWM/PFM operation to reduce supply current at light loads. SYNC is a negative-edge triggered input that allows synchronization to an external frequency ranging between 270kHz and 450kHz. When SYNC is clocked by an external signal, the converter operates in PWM mode until the load current drops below the PWM to PFM threshold. Thereafter the converter continues operation in PFM mode. 4.3 Shutdown Mode Connecting ENABLE to GND places the TLE6389GV, TLE6389G33 and TLE6389G50 in shutdown mode. In shutdown, the reference, control circuitry, external switching MOSFET, and the oscillator are turn off and the output falls to 0V. Connect ENABLE to IN for normal operation. 4.4 SI_Enable Connecting SI_ENABLE to 5V causes SI_GND to have low impedance. Thus the SI comparator is operational and ca be used to monitor the battery voltage. SO output signal is valid. Connecting SI_ENABLE to GND causes SI_GND to have high impedance. Thus the SI comparator is not able to monitor the battery voltage. SO output signal is invalid. Target Datasheet Rev. 1.7 19 2001-09-17 TLE 6389 4.5 Quiescent Current The device's typical quiescent current is 50A. However, actual applications draw additional current to supply MOSFET switching currents, FB pin current, or external feedback resistors (if used), and both the diode and capacitor leakage currents. For example, with VS at 13.5V and VOUT at 5V, typical no-load supply current for the entire circuit is TBDA. When designing a circuit for high-temperature operation, select a Schottky diode with low reverse leakage. 5 Application Information 5.1 Output Voltage Selection (TLE6389GV only) Select an output voltage between 5V and 15V by connecting FB to a resistor-divider between the output and GND. Select feedback resistor R2 in the 5k to 500k range. R1 is then given by: R1 = R2 [(VOUT / VFB) - 1] where VFB = 1.25V. Add a small ceramic capacitor around 47pF to 100pF in parallel with R1 to compensate for stray capacitance at the FB pin and output capacitor equivalent series resistance (ESR). 5.2 Output Capacitor Selection Choose input- and output-filter capacitors to service inductor currents with acceptable voltage ripple. The input-filter capacitor also reduces peak currents and noise at the voltage source. In addition, connect a low-ESR bulk capacitor (>10F suggested) to the input. Select this bulk capacitor to meet the input ripple requirements and voltage rating, rather than capacitor size. Use the following equation to calculate the maximum RMS input current: IRMS = IOUT[VOUT (VIN - VOUT)]1/2 * VIN When selecting an output capacitor, consider the output- ripple voltage and approximate it as the product of the ripple current and the ESR of the output capacitor. VRIPPLE = [VOUT (VIN - VOUT)] / [2 * fOSC(L) (VIN)] * ESRCOUT where ESRCOUT is the equivalent-series resistance of the output capacitor. Higher values of COUT provide improved output ripple and transient response. Lower oscillator frequencies require a larger-value output capacitor. Verify capacitor selection with light loads during PFM operation, since output ripple is higher under these conditions. LowESR capacitors are recommended. Capacitor ESR is a major contributor to output ripple (usually more than 60%). Ordinary aluminum-electrolytic capacitors have high ESR and should be avoided. Low-ESR aluminum-electrolytic capacitors are acceptable and relatively inexpensive. Low-ESR tantalum capacitors are better and provide a compact Target Datasheet Rev. 1.7 20 2001-09-17 TLE 6389 solution for space-constrained surface-mount designs. Do not exceed the ripple-current ratings of tantalum capacitors. Ceramic capacitors have the lowest ESR overall. Target Datasheet Rev. 1.7 21 2001-09-17 TLE 6389 6 Package Outlines Dimensions in mm Target Datasheet Rev. 1.7 22 2001-09-17 TLE 6389 Published by Infineon Technologies AG, St.-Martin-Strasse 53 D-81541 Munchen (c) Infineon Technologies AG2000 All Rights Reserved. Attention please! The information herein is given to describe certain components and shall not be considered as warranted characteristics. Terms of delivery and rights to technical change reserved. We hereby disclaim any and all warranties, including but not limited to warranties of non-infringement, regarding circuits, descriptions and charts stated herein. Infineon Technologiesis an approved CECC manufacturer. Information For further information on technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies Office in Germany or our Infineon Technologies Representatives worldwide (see address list). Warnings Due to technical requirements components may contain dangerous substances. For information on the types in question please contact your nearest Infineon Technologies Office. Infineon Technologies Components may only be used in life-support devices or systems with the express written approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may be endangered. Target Datasheet Rev. 1.7 23 2001-09-17