DATASHEET ISL95872 FN7974 Rev 0.00 Buck PWM Controller with Internal Compensation and External Reference January 26, 2012 Tracking The ISL95872 is a Single-Phase Synchronous-Buck PWM Features controller featuring Intersils proprietary R4 Technology. The External Reference Tracking R4 modulator has integrated compensation, fast transient performance, accurate switching frequency control, and Intersils R4 Modulator Technology excellent light-load efficiency. These technology advances, - Internal Compensation together with integrated MOSFET drivers and a schottky - Fast, Optimal Transient Response bootstrap diode, allow for a high performance regulator that is Input Voltage Range: 3.3V to 25V highly compact and needs few external components. Differential remote sensing of the output voltage is an Output Voltage Range: 0.5V to 3.3V additional feature. For maximum efficiency, the converter Precision Voltage Regulation automatically enters diode-emulation mode (DEM) during - 0.5% System Accuracy Over -10C to +100C light-load conditions such as system standby. Output Voltage Remote Sense The ISL95872 accepts a wide 3.3V to 25V input voltage range, making it ideal for systems that run on battery or AC-adapter Fixed 300kHz PWM Frequency in Continuous Conduction power sources. It also is a low-cost solution for applications -Proprietary Frequency Control Loop requiring tracking of an external reference voltage during soft- Automatic Diode Emulation Mode for Highest Efficiency start. When the external reference level meets the internal reference voltage, the ISL95872 switches from the external Power-Good Monitor for Soft-Start and Fault Detection reference to the internal reference. The external reference is only used during soft-start. Applications Compact Buck Regulators Requiring External Tracking R VCC +5V C VCC C PVCC V IN 3.3V TO 25V CIN Q HS 1 12 GND BOOT R FB1 RTN1 2 11 RTN UGATE V L OUT O 0.5V TO 3.3V 3 10 EN GPIO PHASE Q LS 4 9 CO REFIN PGOOD C SEN RTN1 C BOOT R O External 0 Reference R FB Voltage R OFS FIGURE 1. ISL95872 APPLICATION SCHEMATIC WITH DCR CURRENT SENSE FN7974 Rev 0.00 Page 1 of 17 January 26, 2012 R OFS1 C SOFT 5 16 PGND SREF 15 6 LGATE FB 14 7 PVCC OCSET 13 8 VCC VO R PGOOD R OCSETISL95872 Application Schematics R VCC +5V C VCC C PVCC V IN 3.3V TO 25V CIN Q GND BOOT HS 112 R FB1 RTN1 RTN UGATE 2 11 V L OUT O 0.5V TO 3.3V EN PHASE GPIO 310 Q REFIN PGOOD LS CO 4 9 C SEN RTN1 C BOOT R O R FB External Reference Voltage 0 R OFS FIGURE 2. ISL95872 APPLICATION SCHEMATIC WITH ONE OUTPUT VOLTAGE SETPOINT AND DCR CURRENT SENSE R VCC +5V C VCC C PVCC V IN 3.3V TO 25V CIN Q GND BOOT HS 112 R FB1 RTN1 RTN UGATE 2 11 V L OUT O R SEN 0.5V TO 3.3V EN PHASE 310 GPIO Q LS REFIN PGOOD CO 4 9 C SEN RTN1 C BOOT R O R 1 R External FB Reference Voltage 0 R 2 FIGURE 3. ISL95872 APPLICATION SCHEMATIC WITH ONE OUTPUT VOLTAGE SETPOINT AND RESISTOR CURRENT SENSE FN7974 Rev 0.00 Page 2 of 17 January 26, 2012 R OFS1 R OFS1 C SOFT PGND SREF PGND SREF 5 16 5 16 C SOFT LGATE LGATE FB FB 6 15 6 15 OCSET PVCC OCSET PVCC 7 14 7 14 VCC VCC VO VO 8 13 8 13 R OFS R R PGOOD PGOOD R OCSET R OCSET