The ISL6381 is an EAPP Hybrid Digital 4-Phase PWM controller

and is designed to be compliant to Intel VR12.5/VR12

specifications and control the microprocessor core or memory

voltage regulator. It includes programmable functions and

telemetries for easy use, high system flexibility and

overclocking applications using SMBus, PMBus, or I2C

interface, which is designed to be conflict free with CPU’s SVID

bus. This hybrid digital approach eliminates the need of NVM

and Firmware often seen in a full digital solution and

significantly reduces design complexity, inventory and

manufacturing costs.

The ISL6381 utilizes Intersil’s proprietary Enhanced Active Pulse

Positioning (EAPP) modulation scheme to achieve the extremely

fast transient response with fewer output capacitors. The

ISL6381 accurately monitors the load current via the IMON pin

and reports this information via the IOUT register to the

microprocessor, which sends a PSI# signal to the controller at

low power mode via SVID bus. The controller enters 1- or

2-phase operation in low power mode (PSI1); in the ultra low

power mode (PSI2, PSI3), it operates in single phase with diode

emulation option. In low power modes, the magnetic core and

switching losses are significantly reduced, yielding high

efficiency at light load. After the PSI# signal is deasserted, the

dropped phase(s) are added back to sustain heavy load

transient response and efficiency. In addition, the ISL6381

features auto-phase shedding to optimize the efficiency from

light to full load for Green Environment without sacrificing the

transient performance.

Today’s microprocessors require a tightly regulated output voltage

position versus load current (droop). The ISL6381 senses the

output current continuously by measuring the voltage across a

dedicated current sense resistor or the DCR of the output

inductor. The sensed current flows out of the FB pin to develop the

precision voltage drop across the feedback resistor for droop

control. Current sensing circuits also provide the needed signals

for channel-current balancing, average overcurrent protection and

individual phase current limiting. The TM pin senses an NTC

thermistor’s temperature, which is internally digitized for thermal

monitoring and for integrated thermal compensation of the

current sense elements of the regulator.

The ISL6381 features remote voltage sensing and completely

eliminates any potential difference between remote and local

grounds. This improves regulation and protection accuracy. The

threshold-sensitive enable input is available to accurately

coordinate the start-up of the ISL6381 with other voltage rails.

Features

• Intel VR12.5/VR12 compliant

- SerialVID with programmable IMAX, TMAX, BOOT,

ADDRESS OFFSET registers

- VR12.5 core and VR12/VR12.5 memory

• Intersil’s proprietary EAPP Hybrid Digital Enhanced Active

Pulse Positioning (EAPP) Modulation Scheme (Patented)

- SMBus/PMBus/I2C interface with SVID conflict free

- NVM and firmware free for low cost and easy use

- Auto phase shedding option for greener environment

- Variable frequency control during load transients to

reduce beat frequency oscillation

- Linear control with evenly distributed PWM pulses for

better phase current balance during load transients

- Voltage feed-forward and ramp adjustable options

- High frequency and PSI compensation options

- Proprietary active phase adding and dropping with diode

emulation scheme for enhanced light load efficiency

• 1 to 4-Phase with phase doubler compatibility

• Differential remote voltage sensing

• ±0.5 closed-loop system accuracy over load, line and

temperature

• Programmable 1 or 2-phase operation in PSI1 mode

• Programmable slew rate of fast dynamic VID with Dynamic

VID Compensation (DVC)

• Droop and diode emulation options

• Precision resistor or DCR differential current sensing

- Integrated programmable current sense resistors

- Accurate load-line (droop) programming

- Accurate current monitoring and channel-current

balancing

• True Catastrophic Failure Protection (CFP)

• Average overcurrent protection and channel current limit with

internal current comparators

• Precision overcurrent protection on IMON pin

• Output voltage open sensing protection

• Protection disable option

• Accurate load-line (droop) programming

• Up to 2MHz per phase

• Thermal monitoring and integrated compensation

• Start-up into precharged load

• Pb-free (RoHS compliant)

• 40 Ld 5x5 TQFN