ISL6334DIRZ datasheet(10/28 Pages) RENESAS

10 / 28 page

ISL6334D

FN6802 Rev 4.00

Page 10 of 28

Apr 29, 2016

Functional Pin Description

VCC - Supplies the power necessary to operate the chip. The

controller starts to operate when the voltage on this pin exceeds

the rising POR threshold and shuts down when the voltage on

this pin drops below the falling POR threshold. Connect this pin

directly to a +5V supply.

GND - Bias and reference ground for the IC. The bottom metal

base of ISL6334D is the GND.

EN_PWR - This pin is a threshold-sensitive enable input for the

controller. Connecting the 12V supply to EN_PWR through an

appropriate resistor divider provides a means to synchronize

power-up of the controller and the MOSFET driver ICs. When

EN_PWR is driven above 0.870V, the ISL6334D is active

depending on status of the EN_VTT, the internal POR, and

pending fault states. Driving EN_PWR below 0.735V will clear all

fault states and prime the ISL6334D to soft-start when

re-enabled.

EN_VTT - This pin is another threshold-sensitive enable input for

the controller. It’s typically connected to VTT output of VTT

voltage regulator in the computer mother board. When EN_VTT is

driven above 0.870V, the ISL6334D is active depending on status

of the EN_PWR, the internal POR, and pending fault states.

Driving EN_VTT below 0.735V will clear all fault states and prime

the ISL6334D to soft-start when re-enabled.

VDIFF, VSEN and RGND - VSEN and RGND form the precision

differential remote-sense amplifier. This amplifier converts the

differential voltage of the remote output to a single-ended

voltage referenced to local ground. VDIFF is the amplifier’s

output and the input to the regulation and protection circuitry.

Connect VSEN and RGND to the sense pins of the remote load.

FB and COMP - Inverting input and output of the error amplifier

respectively. FB can be connected to VDIFF through a resistor.

COMP is tied back to FB through an external R-C network to

compensate the regulator.

DAC and REF - The DAC pin is the output of the precision internal

DAC reference. The REF pin is the positive input of the Error

Amplifier. In typical applications, a 1kΩ, 1% resistor is used

between DAC and REF to generate a precision offset voltage. This

voltage is proportional to the offset current determined by the

offset resistor from OFS to ground or VCC. A capacitor is used

between REF and ground to smooth the voltage transition during

Dynamic VID™ operations.

VR_RDY - VR_RDY indicates that soft-start has completed and

the output voltage is within the regulated range around the VID

setting. It is an open-drain logic output. When OCP or OVP occurs,

VR_RDY will be pulled to low. It will also be pulled low if the

output voltage is below the undervoltage threshold.

OFS - The OFS pin can be used to program a DC offset current,

which will generate a DC offset voltage between the REF and

DAC pins. The offset current is generated via an external resistor

and precision internal voltage references. The polarity of the

offset is selected by connecting the resistor to GND or VCC. For no

offset, the OFS pin should be left unterminated.

TCOMP - Temperature compensation scaling input. The voltage

sensed on the TM pin is utilized as the temperature input to adjust

IMON and the overcurrent protection limit to effectively

compensate for the temperature coefficient of the current sense

element. To implement the integrated temperature compensation,

a resistor divider circuit is needed with one resistor being

connected from TCOMP to VCC of the controller and another

resistor being connected from TCOMP to GND. Changing the ratio

of the resistor values will set the gain of the integrated thermal

compensation. When the integrated temperature compensation

function is not used, connect TCOMP to GND.

TM - TM is an input pin for the VR temperature measurement.

Connect this pin through an NTC thermistor to GND and a resistor

to VCC of the controller. The voltage at this pin is reverse

proportional to the VR temperature. The ISL6334D monitors the

VR temperature based on the voltage at the TM pin and outputs

VR_HOT and VR_FAN signals.

VR_HOT - VR_HOT is used as an indication of high VR

temperature. It is an open-drain logic output. It will be pulled low

if the measured VR temperature is less than a certain level, and

open when the measured VR temperature reaches a certain

level. An external pull-up resistor is needed.

VR_FAN - VR_FAN is an output pin with open-drain logic output. It

will be pulled low if the measured VR temperature is less than a

certain level, and open when the measured VR temperature

reaches a certain level. A external pull-up resistor is needed.

PWM1, PWM2, PWM3, PWM4 - Pulse width modulation outputs.

Connect these pins to the PWM input pins of the Intersil driver IC.

The number of active channels is determined by the state of

PWM2, PWM3 and PWM4. Tie PWM2 to VCC to configure for 1-

phase operation. Tie PWM3 to VCC to configure for a 2-phase

operation. Tie PWM4 to VCC to configure for a 3-phase operation.

In addition, tie PSI# to GND to configure for a single phase

operation as well.

ISEN1+, ISEN1-; ISEN2+, ISEN2-; ISEN3+, ISEN3-; ISEN4+, ISEN4-

The ISEN+ and ISEN- pins are current sense inputs to individual

differential amplifiers. The sensed current is used for channel

current balancing and overcurrent protection. Inactive channels

should have their respective current sense inputs left open (for

example, open ISEN4+ and ISEN4- for a 3-phase operation).

For DCR sensing, connect each ISEN- pin to the node between the

RC sense elements. Tie the ISEN+ pin to the other end of the

sense capacitor through a resistor, RISEN. The voltage across the

sense capacitor is proportional to the inductor current. Therefore,

the sense current is proportional to the inductor current and

scaled by the DCR of the inductor and RISEN.

To match the time delay of the internal circuit, a capacitor is

needed between each ISEN+ pin and GND, as described in

“Current Sensing” on page 13.

IMON - IMON is the output pin of sensed, thermally compensated

(if internal thermal compensation is used) average current. The

voltage at the IMON pin is proportional to the load current and the

resistor value, and internally clamped to 1.11V plus the remote

ground potential difference. If the clamped voltage (1.11V) is

triggered, it will initiate the overcurrent shutdown. By choosing the

proper value for the resistor at IMON pin, the overcurrent trip level

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