Increase in GPU clock frequency is accompanied by

associated increase in the demand for power and transientcurrent slew rate. At the same time, the voltage tolerance

requirement during steady-state and transient operation is

becoming more stringent of advanced GPU. The ISL9502 is

a two-phase PWM controller with embedded gate drivers,

which is tailored to meet the power and dynamic

requirements. The two-phase buck converter uses two

interleaved channels to effectively double the output voltage

ripple frequency and thereby reduce output voltage ripple

amplitude with fewer components, lower component cost,

reduced power dissipation, and smaller real estate area.

The heart of the ISL9502 is the patented R3 (Robust Ripple

Regulator?) modulator. Compared with the traditional multiphase buck regulator, R3 technology has the fastest transient

response. This is due to the R3 modulator commanding

variable switching frequency during a load transient.

At heavy load operation of the active mode, ISL9502

commands the two phase continuous conduction mode

(CCM) operation. While the pin SET3 is asserted at the

medium or light load, the ISL9502 smoothly disables one

phase and operates in a one-phase operation. Once in onephase operation, when the GPU further lowers the load

current, the ISL9502 enables diode emulation to maximize

efficiency at light load depending on the logic of SET1 and

SET2.

A 6-bit digital-to-analog converter (DAC) allows dynamic

adjustment of the output voltage from 0.500V to 1.500V with

25mV step. A 0.5 system accuracy of the core output

voltage over temperature is achieved by the ISL9502.

A unity-gain differential amplifier is provided for remote GPU

die sensing. This allows the voltage on the GPU die to be

accurately measured and regulated. Current sensing can be

realized using either lossless inductor DCR sensing or

precision resistor sensing. A single NTC thermistor network

can thermally compensates the gain and the time constant of

the DCR variations. Droop control, also referred as adaptive

voltage positioning (AVP), is implemented in ISL9502 to

reduce output decoupling capacitors and achieve more costeffective transient-load regulation.

Features

? Precision Two-phase Buck PWM controller

- 0.5 System Accuracy Over Temperature

- Active Voltage Positioning Capability

? Internal Gate Driver with 2A Driving Capability

? Superior Load Transient Response

? Dynamic Phase Adding/Dropping

? Voltage Selection Input

- 6-Bit VSEL Input

- 0.500V to 1.500V in 25mV Steps

- Supports VSEL Change On-The-Fly

? Multiple Current-Sensing Schemes Supported

- Lossless Inductor DCR Current Sensing

- Precision Resistive Current Sensing

? Thermal Monitor

? User Programmable Switching Frequency

? Differential Remote GPU Voltage Sensing

? Static and Dynamic Current Sharing

? Overvoltage, Undervoltage, and Overcurrent Protection

? Pb-Free Plus Anneal Available (RoHS Compliant)