6

HV9911

Pin #

Pin

Description

1V

IN

This pin is the input of a 250V high voltage regulator.

2V

DD

This is a power supply pin for all internal circuits. It must be bypassed with a low ESR capacitor to

GND (at least 0.1uF).

3

GATE

This pin is the output gate driver for an external N-channel power MOSFET.

4

GND

Ground return for all circuits. This pin must be connected to the return path from the input.

5CS

This pin is used to sense the drain current of the external power FET. It includes a built-in 100ns

(min) blanking time.

6SC

Slope compensation for current sense. A resistor between SC and GND will program the slope

compensation. In case of constant off-time mode of operation, slope compensation is unnecessary

and the pin can be left open.

7R

T

This pin sets the frequency or the off-time of the power circuit. A resistor between RT and GND will

program the circuit in constant frequency mode. A resistor between RT and GATE will program the

circuit in a constant off-time mode.

8

SYNC

This I/O pin may be connected to the SYNC pin of other HV9911 circuits and will cause the oscillators

to lock to the highest frequency oscillator.

9C

LIM

This pin provides a programmable input current limit for the converter. The current limit can be set by

using a resistor divider from the REF pin. Soft start can also be provided using this pin.

10

REF

This pin provides 2% accurate reference voltage. It must be bypassed with at least a 10nF - 0.22µF

capacitor to GND.

11

FAULT

This pin is pulled to ground when there is an output short circuit condition or output over voltage

condition. This pin can be used to drive an external MOSFET in the case of boost converters to

disconnect the load from the source.

12

OVP

This pin provides the over voltage protection for the converter. When the voltage at this pin exceeds

1.25V, the gate output of the HV9911 is turned off and FAULT goes low. The IC will turn on when

the power is recycled.

13

PWMD

When this pin is pulled to GND (or left open), switching of the HV9911 is disabled. When an external

TTL high level is applied to it, switching will resume.

14

COMP

Stable Closed loop control can be accomplished by connecting a compensation network between

COMP and GND.

15

I

REF

The voltage at this pin sets the output current level. The current reference can be set using a resistor

divider from the REF pin.

16

FDBK

This pin provides output current feedback to the HV9911 by using a current sense resistor.

Pin Description