HV9608

5

A122104

Functional Block Diagram

High Voltage

startup regulator

VIN

REF

UVLO

Bandgap

reference

+

-

1.135V

RT

Oscillator

SQ

R

VS

+

-

1.135V

pwm

Comp

+

eAmp

1.135V

0.6V

+

-

GATE

VDD

driver

FB

Delay

Logic

AGATE

DT1

DT2

100ns blanking

CS

+

-

3.85V

Ι

Ι

UVLO

SS

GND

+

-

0.6V

+

-

ramp

SC

R

POR

+

-

1.135V

5.45V

Functional Description

HIGH VOLTAGE REGULATOR

internal high voltage linear regulator provides a regulated output

higher than its output voltage will disable the regulator. Therefore,

pin. Alternatively, the high voltage regulator can continuously

supply bias current up to 20mA powering the gate driver and all

internal circuits of HV9608. The need for a bootstrap power supply

would be eliminated in this case. However, caution must be taken

to maintain the HV9608 within its package power dissipation limits.

The output of the linear regulator is equipped with an under voltage

protection comparator that disables all internal circuits when the

provided.

INPUT UNDER VOLTAGE LOCKOUT (UVLO)

The HV9608 provides a programmable under voltage protection

input (UVLO pin) that allows independent setting of the turn-on and

the turn-off limits for the input voltage of the DC/DC converter.

When the voltage applied to the UVLO pin exceeds 1.135V, the

and the DC/DC converter starts switching. At the same time, a

current of 14µA is sourced from the UVLO pin. This current sets

the hysteresis that can be calculated in accordance with the

following equation:

12

12

14

UVLO

R R

VA

R

R

µ

⋅

∆=

⋅

+

,

OSCILLATOR FREQUENCY

The switching frequency of the HV9608 can be programmed using

[]

[]

9

1

300 10

OSC

T

T

FHz

R

CF

−

⎛⎞

−⋅

⎜⎟

⎜⎟

⎝⎠

=

SOFT START

threshold, a 7µA current is sourced from the SS pin into an

up linearly, the output of the error amplifier (COMP) gradually

increases until regulation of the output voltage is achieved. Sizing

sized properly, no overshoot of the output voltage or excessive

discharged to zero.