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)