Step-Down PWM Controller

® ISL6445 Data Sheet September 9, 2005 FN9230.0 PRELIMINARY 1.4MHz Dual, 180° Out-of-Phase, Step-Down PWM Controller The ISL6445 is a high-performance, dual-output PWM controller optimized for converting wall adapter, battery or network intermediate bus DC input supplies into the system supply voltages required for a wide variety of applications. Each output is adjustable down to 0.8V. The two PWMs are synchronized 180o out of phase reducing the RMS input current and ripple voltage. The ISL6445 incorporates several protection features. An adjustable overcurrent protection circuit monitors the output current by sensing the voltage drop across the lower MOSFET. Hiccup mode overcurrent operation protects the DC/DC components from damage during output overload/short circuit conditions. Each PWM has an independent logic-level shutdown input (SD1 and SD2). A single PGOOD signal is issued when soft-start is complete on both PWM controllers and their outputs are within 10% of the set point. Thermal shutdown circuitry turns off the device if the junction temperature exceeds +150°C. Features • Wide Input Supply Voltage Range - 5.6V to 24V - 4.5V to 5.6V • Two Independently Programmable Output Voltages • Switching Frequency . . . . . . . . . . . . . . . . . . . . . . .1.4MHz • Out of Phase PWM Controller Operation - Reduces Required Input Capacitance and Power Supply Induced Loads • No External Current Sense Resistor - Uses Lower MOSFET’s rDS(ON) • Programmable Soft-Start • Extensive Circuit Protection Functions - PGOOD - UVLO - Overcurrent - Overtemperature - Independent Shutdown for Both PWMs • Excellent Dynamic Response - Voltage Feed-Forward with Current Mode Control • Pb-Free Plus Anneal Available (RoHS Compliant) Pinout ISL6445 (QSOP) TOP VIEW 1 LGATE2 2 BOOT2 3 UGATE2 4 PHASE2 5 ISEN2 6 PGOOD 7 VCC5 8 SD2 9 SS2 10 OCSET2 11 FB2 12 VIN LGATE1 24 BOOT1 23 UGATE1 22 PHASE1 21 ISEN1 20 PGND 19 SD1 18 SS1 17 SGND 16 OCSET1 15 FB1 14 BIAS 13 Applications • Power Supplies with Two Outputs • xDSL Modems/Routers • DSP, ASIC, and FPGA Power Supplies • Set-Top Boxes • Dual Output Supplies for DSP, Memory, Logic, µP Core and I/O • Telecom Systems Ordering Information PART NUMBER PART MARKING TEMP. RANGE (°C) -40 to 85 PACKAGE 24 Ld QSOP (Pb-free) PKG. DWG. # M24.15 ISL6445IAZ* ISL6445IAZ (See Note) NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. *Add “-TK” suffix for tape and reel. 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2005. All Rights Reserved All other trademarks mentioned are the property of their respective owners. ISL6445 Typical Application Schematic VCC5 +12V C2 4.7µF D1 BAT54HT1 C3 10µF VIN SS1 C4 0.1µF BOOT1 17 12 VCC5 7 9 SS2 C5 0.1µF BOOT2 D2 BAT54HT1 C6 10µF + C1 56µF 23 2 C7 0.1µF VOUT1 +1.8V, 2A C9 + 150µF L1 3.2µH Q1 FDS6912A R1 1.4K UGATE1 22 PHASE1 21 ISEN1 20 LGATE1 PGND FB1 ISL6445IA 3 4 5 UGATE2 PHASE2 ISEN2 R2 1.4K C8 0.1µF L2 3.2µH Q2 FDS6912A + C10 150µF R5 31.6K VOUT2 +3.3V, 2A R3 12.4K 24 19 14 18 1 LGATE2 11 15 FB2 OCSET1 R7 121K 10 OCSET2 R8 121K R4 10K SD1 SD2 R6 10K 8 16 13 6 PGOOD R9 10K SGND BIAS PGOOD VCC5 2 FN9230.0 September 9, 2005 Block Diagram BOOT1 UGATE1 PHASE1 VCC_5V LGATE1 PGND ADAPTIVE DEAD-TIME DIODE EMULATION V/I SAMPLE TIMING ADAPTIVE DEAD-TIME DIODE EMULATION V/I SAMPLE TIMING PGOOD SD1 VIN SGND SD2 VCC BOOT2 UGATE2 PHASE2 VCC LGATE2 POR PGND ENABLE BIAS SUPPLIES REFERENCE FAULT LATCH SOFT-START UV PGOOD UV PGOOD 3 FB3 800kΩ FB1 180kΩ 18.5pF ISL6445 18.5pF 800kΩ + 16kΩ OC1 OC2 PWM2 + 16kΩ ERROR AMP 2 180kΩ VSEN2 + PWM1 + SOFT2 + 0.8V REF SS1 ERROR AMP 1 + DUTY CYCLE RAMP GENERATOR PWM CHANNEL PHASE CONTROL 0.8V REF ISEN2 ISEN1 CURRENT SAMPLE CURRENT SAMPLE + CURRENT SAMPLE + CURRENT SAMPLE OCSET1 OCSET2 + 0.8V REFERENCE 0.8V REFERENCE + + FN9230.0 September 9, 2005 OC1 OC2 + VIN SAME STATE FOR 2 CLOCK CYCLES REQUIRED TO LATCH OVERCURRENT FAULT VCC SAME STATE FOR 2 CLOCK CYCLES REQUIRED TO LATCH OVERCURRENT FAULT ISL6445 Absolute Maximum Ratings Supply Voltage (VCC_5V Pin) . . . . . . . . . . . . . . . . . . . . -0.3V to +7V Input Voltage (VIN Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+27V BOOT1, 2 and UGATE1, 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . +35V PHASE1, 2 and ISEN1, 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . +27V BOOT1, 2 with Respect to PHASE1, 2 . . . . . . . . . . . . . . . . . . +6.5V UGATE1, 2. . . . . . . . . . . . (PHASE1, 2 - 0.3V) to (BOOT1, 2 +0.3V) Thermal Information Thermal Resistance (Typical) θJA (°C/W) 24 Lead QSOP (Note 1). . . . . . . . . . . . . . . . . . . . . . 85 Maximum Junction Temperature (Plastic Package) . -55°C to 150°C Maximum Storage Temperature Range . . . . . . . . . . . -65°C to 150°C Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTE: 1. θJA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details. Electrical Specifications Recommended operating conditions unless otherwise noted. Refer to Block Diagram and Typical Application Schematic. VIN = 5.6V to 24V, or VCC5 = 5V ±10%, TA = -40°C to 85°C (Note 3), Typical values are at TA = 25°C TEST CONDITIONS MIN TYP MAX UNITS PARAMETER VIN SUPPLY Input Voltage Range VCC_5V SUPPLY (Note 3) Input Voltage Output Voltage Maximum Output Current SUPPLY CURRENT Shutdown Current (Note 4) Operating Current (Note 5) REFERENCE SECTION Nominal Reference Voltage Reference Voltage Tolerance POWER-ON RESET Rising VCC_5V Threshold Falling VCC_5V Threshold OSCILLATOR Total Frequency Variation Peak-to-Peak Sawtooth Amplitude (Note 6) 5.6 12 24 V 4.5 VIN > 5.6V, IL = 20mA VIN = 12V 4.5 60 5.0 5.0 - 5.6 5.5 - V V mA SD1 = SD2 = GND - 50 2.0 375 4.0 µA mA -1.0 0.8 - 1.0 V % 4.25 3.95 4.45 4.2 4.5 4.4 V V 1.25 VIN = 12V VIN = 5V - 1.4 1.6 0.667 1.0 1.55 - MHz V V V Ramp Offset (Note 7) SHUTDOWN1/SHUTDOWN2 HIGH Level (Converter Enabled) LOW Level (Converter Disabled) PWM CONVERTERS Output Voltage FB Pin Bias Current Maximum Duty Cycle Minimum Duty Cycle Cout = 1000pF, TA = 25°C Internal Pull-up (3µA) 2.0 - - 0.8 V V 93 - 0.8 4 150 - V nA % % 4 FN9230.0 September 9, 2005 ISL6445 Electrical Specifications Recommended operating conditions unless otherwise noted. Refer to Block Diagram and Typical Application Schematic. VIN = 5.6V to 24V, or VCC5 = 5V ±10%, TA = -40°C to 85°C (Note 3), Typical values are at TA = 25°C (Continued) TEST CONDITIONS MIN TYP MAX UNITS PARAMETER PWM CONTROLLER ERROR AMPLIFIERS DC Gain (Note 7) Gain-Bandwidth Product (Note 7) Slew Rate (Note 7) Maximum Output Voltage (Note 7) Minimum Output Voltage (Note 7) PWM CONTROLLER GATE DRIVERS (Note 8) Sink/Source Current Upper Drive Pull-Up Resistance Upper Drive Pull-Down Resistance Lower Drive Pull-Up Resistance Lower Drive Pull-Down Resistance Rise Time Fall Time POWER GOOD AND CONTROL FUNCTIONS PGOOD LOW Level Voltage PGOOD Leakage Current PGOOD Upper Threshold, PWM 1 and 2 PGOOD Lower Threshold, PWM 1 and 2 ISEN and CURRENT LIMIT Full Scale Input Current (Note 9) Overcurrent Threshold (Note 9) OCSET (Current Limit) Voltage SOFT-START Soft-Start Current PROTECTION Thermal Shutdown Rising 80 5.9 0.9 - 88 2.0 - 3.6 dB MHz V/µs V V VCC5 = 4.5V VCC5 = 4.5V VCC5 = 4.5V VCC5 = 4.5V COUT = 1000pF COUT = 1000pF - 400 8 3.2 8 1.8 18 18 - mA ns ns Pull-up = 100kΩ - 0.1 - 0.5 ±1.0 120 95 V µA % % Fraction of set point Fraction of set point 105 80 ROCSET = 110kΩ - 32 64 1.75 - µA µA V - 5 - µA - 150 20 - °C °C Hysteresis NOTES: 2. Specifications at -40°C and 85°C are guaranteed by design, not production tested. 3. In normal operation, where the device is supplied with voltage on the VIN pin, the VCC_5V pin provides a 5V output capable of 60mA (min). When the VCC_5V pin is used as a 5V supply input, the internal LDO regulator is disabled and the VIN input pin must be connected to the VCC_5V pin. (Refer to the Pin Descriptions section for more details.) 4. This is the total shutdown current with VIN = VCC_5V = PVCC = 5V. 5. Operating current is the supply current consumed when the device is active but not switching. It does not include gate drive current. 6. The peak-to-peak sawtooth amplitude is production tested at 12V only; at 5V this parameter is guaranteed by design. 7. Guaranteed by design; not production tested. 8. Not production tested; guaranteed by characterization only. 9. Guaranteed by design. The full scale current of 32µA is recommended for optimum current sample and hold operation. See the Feedback Loop Compensation Section below. 5 FN9230.0 September 9, 2005 ISL6445 Typical Performance Curves (From ISL6445EVAL1 evaluation board) 3.4 PWM1 OUTPUT VOLTAGE (V) PWM2 OUTPUT VOLTAGE (V) 0.5 1.5 2 3 4 4.5 3.39 3.38 3.37 3.36 3.35 3.34 3.33 3.32 3.31 3.3 3.4 3.39 3.38 3.37 3.36 3.35 3.34 3.33 3.32 3.31 3.3 0 1 2.5 3.5 0