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