ISL62871 Datasheet, PDF (1/25 Pages) Intersil Corporation – PWM DC/DC Controller With VID Inputs For Portable GPU Core-Voltage Regulator

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Data Sheet
ISL62871, ISL62872
August 14, 2008
FN6707.0
PWM DC/DC Controller With VID Inputs
For Portable GPU Core-Voltage Regulator
The ISL62871 and ISL62872 IC’s are Single-Phase
Synchronous-Buck PWM voltage regulators featuring
Intersil’s Robust Ripple Regulator (R³) Technology™. The
wide 3.3V to 25V input voltage range is ideal for systems
that run on battery or AC-adapter power sources. The
ISL62871 and ISL62872 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 two (ISL62871) or four
(ISL62872) resistor-programmed setpoint reference voltages
that directly set the output voltage of the converter between
0.5V to 1.5V, and up to 3.3V using a feedback voltage
divider. Optionally, an external reference such as the DAC
output from a microcontroller, can be used by either IC to
program the setpoint reference voltage, and still maintain the
controlled slew-rate features. Robust integrated MOSFET
drivers and Schottky bootstrap diode reduce the
implementation area and lower component cost.
Intersil’s R³ Technology™ combines the best features of
both fixed-frequency and hysteretic PWM control. The PWM
frequency is 300kHz during static operation, becoming
variable during changes in load, setpoint voltage, and input
voltage when changing between battery and AC-adapter
power. The modulators ability to change the PWM switching
frequency during these events in conjunction with external
loop compensation produces superior transient response.
For maximum efficiency, the converter automatically enters
diode-emulation mode (DEM) during light-load conditions
such as system standby.
Features
• Input Voltage Range: 3.3V to 25V
• Output Voltage Range: 0.5V to 3.3V
• Output Load up to 30A
• Extremely Flexible Output Voltage Programmability
- 2-Bit VID (ISL62872) Selects Four Independent
Setpoint Voltages
- 1-Bit VID (ISL62871) Selects Two Independent Setpoint
Voltages
- Simple Resistor Programming of Setpoint Voltages
- Accepts External Setpoint Reference Such as DAC
• ±0.75% System Accuracy: -10°C to +100°C
• One Capacitor Programs Soft-start and Setpoint Slew-rate
• Fixed 300kHz PWM Frequency in Continuous Conduction
• External Compensation Affords Optimum Control Loop
Tuning
• Automatic Diode Emulation Mode for Highest Efficiency
• Integrated High-current MOSFET Drivers and Schottky
Boot-Strap Diode for Optimal Efficiency
• Choice of Overcurrent Detection Schemes
- Lossless Inductor DCR Current Sensing
- Precision Resistive Current Sensing
• Power-Good Monitor for Soft-Start and Fault Detection
• Fault Protection
- Undervoltage
- Overvoltage
- Overcurrent (DCR-Sense or Resistive-Sense
Capability)
- Over-Temperature Protection
- Fault Identification by PGOOD Pull-Down Resistance
• Pb-Free (RoHS compliant)
Applications
• Mobile PC Graphical Processing Unit VCC rail
• Mobile PC I/O Controller Hub (ICH) VCC rail
• Mobile PC Memory Controller Hub (GMCH) VCC rail
• Built-in voltage margin for system-level test
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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