6

Functional Pin Descriptions

ISL6522B (SOIC)

TOP VIEW

ISL6522B (QFN)

TOP VIEW

RT

This pin provides oscillator switching frequency adjustment.

200kHz switching frequency is increased according to the

following equation:

following equation:

OCSET

the converter overcurrent (OC) trip point according to the

following equation:

An overcurrent trip cycles the soft-start function.

SS

Connect a capacitor from this pin to ground. This capacitor,

along with an internal 10

µA current source, sets the soft-start

interval of the converter.

COMP and FB

COMP and FB are the available external pins of the error

amplifier. The FB pin is the inverting input of the error

amplifier and the COMP pin is the error amplifier output.

These pins are used to compensate the voltage-control

feedback loop of the converter.

EN

This pin is the open-collector enable pin. Pull this pin below

1V to disable the converter. In shutdown, the soft-start pin is

discharged and the UGATE and LGATE pins are held low.

GND

Signal ground for the IC. All voltage levels are measured

with respect to this pin.

PHASE

Connect the PHASE pin to the upper MOSFET source. This

pin is used to monitor the voltage drop across the MOSFET

for overcurrent protection. This pin also provides the return

path for the upper gate drive.

UGATE

Connect UGATE to the upper MOSFET gate. This pin

provides the gate drive for the upper MOSFET. This pin is also

monitored by the adaptive shoot through protection circuitry to

determine when the upper MOSFET has turned off.

BOOT

This pin provides bias voltage to the upper MOSFET driver.

A bootstrap circuit may be used to create a BOOT voltage

suitable to drive a standard N-Channel MOSFET.

PGND

This is the power ground connection. Tie the lower MOSFET

source to this pin.

LGATE

Connect LGATE to the lower MOSFET gate. This pin provides

the gate drive for the lower MOSFET. This pin is also

monitored by the adaptive shoot through protection circuitry to

determine when the lower MOSFET has turned off.

PVCC

Provide a bias supply for the lower gate drive to this pin.

VCC

Provide a 12V bias supply for the chip to this pin.

8

9

10

11

12

13

14

7

6

5

4

3

2

1

OCSET

SS

EN

COMP

FB

RT

VCC

LGATE

PGND

BOOT

UGATE

PHASE

GND

PVCC

1

3

4

15

SS

COMP

FB

EN

16

14

13

2

12

10

9

11

6

57

8

PVCC

LGATE

PGND

BOOT

Fs 200kHz

510

6

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+

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Fs 200kHz

410

7

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ISL6522B