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DS20005583A-page 7

HV9912

2.0

PIN DESCRIPTION

Table 2-1 shows the pin description details of HV9912.

TABLE 2-1:

PIN DESCRIPTION TABLE

Pin Number

Name

Description

1

VIN

This pin is the input of a 90V high-voltage regulator.

2

VDD

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

low-ESR capacitor to GND (at least 0.1 µF).

3

GATE

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

4

GND

This is the ground return for all the low-power analog internal circuitry. This pin must

be connected to the return path from the input.

5

CS

This pin is used to sense the source current of the external power FET. It includes a

built-in 100 ns (minimum) blanking time.

6

SC

This pin is used to set the slope compensation.

7

RT

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

program the circuit in Constant Frequency mode.

8

SYNC

This I/O pin may be connected to the SYNC pin of other HV9912 circuits and will

cause the oscillators to lock to the highest frequency oscillator.

9

CLIM

This pin provides a programmable input current limit for the converter. The current

limit can be set using a resistor divider from the REF pin.

10

REF

This pin provides 2% accurate reference voltage. It must be bypassed with a

0.01 μF–0.1 μF capacitor to GND.

11

FAULT

This pin is pulled to ground when there is an Output Short-circuit condition or Output

Overvoltage 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 overvoltage protection for the converter. When the voltage at

this pin exceeds 5V, the GATE output of the HV9912 is turned off, and the FAULT

goes low. The IC will turn on when the voltage at the pin goes below 4.5V.

13

PWMD

When this pin is pulled to GND (or left open), switching of the HV9912 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 net-

work between COMP and GND. This capacitor also controls the hiccup time.

15

IREF

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 HV9912 by using a current sense

resistor.