IR3500A is the control IC of Infineon's XPhase3 distributed multiphase architecture. Rather than driving the power MOSFETs itself, it manages the whole regulator and talks to any number of XPhase3 phase ICs, each of which drives and monitors a single phase of a multiphase buck converter. This split lets a high-current processor voltage regulator scale simply by adding phases, while one IR3500A holds the voltage setpoint, the load line and all the protection. The result is a CPU or ASIC power supply that is smaller, cheaper and easier to lay out than a monolithic multiphase controller, because the gate drive and current sense move out to the phase ICs next to each inductor.

The output voltage is commanded by an 8-bit VID code, and a VID-select pin configures the part for Intel VR11 or for AMD 5-bit or 6-bit PVID, including the start-up to a 1.1V boot voltage. A true differential remote-sense amplifier measures the voltage right at the load with under 50µA of bias current, and the overall system setpoint accuracy is 0.5%. Dynamic VID transitions, the load-line (droop) impedance and the VID offset are all programmable, so the regulator can be tuned to the processor's power-delivery specification without changing the silicon.

A daisy-chain digital phase-timing clock, programmable from 250kHz to 9MHz, sets a per-phase switching frequency of 250kHz to 1.5MHz with no external timing components, and it interleaves the phases automatically. Protection is comprehensive: a programmable converter current limit with hiccup, central over-voltage detection that both signals the system and commands the phase ICs, an IC bias linear-regulator controller with its own UVLO, a programmable VRHOT thermal flag driven from an NTC thermistor on the power stage, and detection of an open remote-sense line or an open control loop. The device is supplied in a 32-lead 5mm x 5mm MLPQ, RoHS compliant.

Note: Values are taken from the Infineon / International Rectifier IR3500A datasheet. Confirm every parameter, and the matching phase IC, against the latest official datasheet before committing a design.

IR3500A under ordering code 111-4043PBF is supplied in a thermally enhanced 32-lead MLPQ (Power Quad Leadless) package with a 5mm x 5mm body and an exposed thermal pad, with a typical junction-to-ambient thermal resistance of 28°C/W and a junction-to-case figure of 2°C/W. The leadless QFN-style outline keeps the high-pin-count control IC compact next to the processor socket, and the "PbF" suffix marks the lead-free (RoHS) finish. The reel ordering option is IR3500AMTRPBF.

The 32-lead MLPQ of IR3500A groups by function as follows:

• Pins 8 to 1 - VID0 to VID7: The 8-bit VID code inputs that command the output voltage through the internal DAC.
• Pin 32 - VIDSEL: VID mode select, configuring Intel VR11 or AMD 5-/6-bit PVID.
• Pin 21 - VDAC: DAC output, the commanded reference voltage for the loop.
• Pin 19 - VSETPT: Setpoint programming for the reference.
• Pin 9 - ENABLE: Enable input for the control IC.
• Pin 13 - VOSEN+ / Pin 12 - VOSEN-: True differential remote-sense inputs taken at the load, with Pin 14 - VO as the sensed output.
• Pin 15 - FB / Pin 16 - EAOUT: Feedback input and high-speed error-amplifier output for loop compensation.
• Pin 17 - VDRP / Pin 18 - IIN: Droop (load-line) voltage and the averaged current input that sets droop and current limit.
• Pin 20 - OCSET: Over-current threshold programming.
• Pin 22 - SS/DEL: Soft-start and delay timing.
• Pin 23 - ROSC/OVP: Oscillator frequency set and over-voltage threshold.
• Pin 27 - PHSIN / Pin 26 - PHSOUT / Pin 25 - CLKOUT: The daisy-chain phase-timing bus that clocks and interleaves the phase ICs.
• Pin 10 - VRHOT / Pin 11 - HOTSET: Thermal flag output and its threshold, driven from an NTC thermistor on the power stage.
• Pin 31 - PGOOD: Power-good output.
• Pin 28 - VCCL / Pin 29 - VCCLFB / Pin 30 - VCCLDRV: The IC bias linear-regulator supply, feedback and drive, with Pin 24 - LGND as the logic ground.

The parts below are reference alternatives and related devices for multiphase processor power. A multiphase VR controller is tightly coupled to its phase ICs and the target VID standard; verify the architecture, VID support and phase-IC compatibility before substituting.

Selection Tips: Choose IR3500A with matching XPhase3 phase ICs (such as IR3505) for a scalable, high-current Intel VR11 or AMD PVID processor rail. A monolithic controller such as ISL6336A suits a fixed phase count, while an integrated regulator (IR38060M) or a single-phase controller (IRU3037A) fits the lower-current auxiliary rails around the processor.

Infineon Technologies AG, headquartered in Neubiberg, Germany, is a leading supplier of power semiconductors and power-management ICs. The IR3500A and the XPhase3 architecture originate with International Rectifier, the power-conversion pioneer that Infineon acquired in 2015, and they sit within Infineon's multiphase digital and analog voltage-regulator portfolio for computing and server processors.

IR3500A is a legacy IR control IC for Intel VR11 and AMD PVID processor power. Infineon supplies the companion XPhase3 phase ICs and the high-current power MOSFETs that complete the regulator, giving a single-vendor path from the control IC to the power stage of a processor voltage regulator.