ISL95870

PWM DC/DC Controller with VID Inputs for Portable GPU Core-Voltage Regulator

OVERVIEW

The ISL95870, ISL95870A, ISL95870B ICs are Single-Phase Synchronous-Buck PWM regulators featuring Intersil’s proprietary R4 Technology™. The wide 3.3V to 25V input voltage range is ideal for systems that run on battery or AC-adapter power sources. The ISL95870A and ISL95870B are low-cost solutions for applications requiring dynamically selected slew-rate controlled output voltages. The soft-start and dynamic setpoint slew-rates are capacitor programmed. Voltage identification logic-inputs select four (ISL95870A, ISL95870B) resistor-programmed setpoint reference voltages that directly set the output voltage of the converter between 0.5V and 1.5V, and up to 5V with a feedback voltage divider.

Compared with R3 modulator, the R4 modulator has equivalent light-load efficiency, faster transient performance, accurately regulated frequency control and all internal compensation. These updates, together with integrated MOSFET drivers and schottky bootstrap diode, allow for a high-performance regulator that is highly compact and needs few external components. The differential remote sensing for output voltage and selectable switching frequency are another two new functions. For maximum efficiency, the converter automatically enters diode-emulation mode (DEM) during light-load conditions such as system standby.

KEY FEATURES

  • Input Voltage Range: 3.3V to 25V
  • Output Voltage Range: 0.5V to 5V
  • Precision Regulation
  • Proprietary R4™ Frequency Control Loop
  • ±0.5% System Accuracy Over -10°C to +100°C
  • Optimal Transient Response
  • Intersil’s R4™ Modulator Technology
  • Output Remote Sense
  • Extremely Flexible Output Voltage Programmability
  • 2-Bit VID Selects Four Independent Setpoint Voltages for ISL95870B
  • 2-Bit VID Selects Four Dependent or Three Independent Setpoint Voltages for ISL95870A
  • Simple Resistor Programming of Setpoint Voltages
  • Selectable 300kHz, 500kHz, 600kHz or 1MHz PWM Frequency in Continuous Conduction
  • Automatic Diode Emulation Mode for Highest Efficiency
  • Power-Good Monitor for Soft-Start and Fault Detection

BLOCK DIAGRAM

 Block Diagram

PARAMETRICS

Parameters
ISL95870
Input Voltage Min (V)
3.3
IS (typ)
1.2 mA
Input Voltage Max (V)
25
Parametric Applications
GPU, ICH, GMCH
Output Voltage Min (V)
0.5
Qualification Level
Standard
Output Voltage Max (V)
5
VID
Yes
Output Current Max (A)
30
Bias Voltage Range (V)
5
VBIAS (min)
4.75 V
Can Sample
YES
VBIAS (max) (V)
5.25
Temperature Range
-40 to +100
IS (min)
1 µA

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