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Pin Descriptions

Pin Number

Function

Description

Interface Schematic

1, 5

VDD, VDIG

Bias supply Pin. Connect supply voltage

to this pin with appropriate filtering.

2

VG2CONT

Control voltage of the VG2. Use a resistor divider between

VDD and GND to set the voltage. VG2 is typically 1.3V

lower than the VG2CONT

10

VG2

Second gate control.

3

SW

Internal switch resistance control pin. If left floating, VSW

defaults to HIGH.

4

EN

Enable pin. System is enabled when Ven is HIGH (VDIG). If

left floating, Ven defaults to HIGH (enabled).

14

DISBLSC

Disables short circuit lock down when pulled to ground.

Leave it floating to enable short circuit lock down.

6

CPOUT

Negative voltage generator charge pump output. Negative

voltage generator needs a flying capacitor, a reservoir

capacitor and two diodes to operate. Please refer to the

application schematic for more info.

7

VGATEFB

Control pin for VGATEFB. Float VGATEFB when a

depletion mode transistor is biased. Selects the mode of

operation along with VNEGFB pin. For detailed usage

please refer to the Table 2.

8

VNEGFB

Feedback (Control) pin for Negative Voltage Generator

Charge Pump. Float to activate the negative voltage

generator / Sort to GND to disable the negative voltage

generator.

9

VNEG

Negative input to the chip. Should be supplied with CPOUT

when negative voltage generator is enabled, or connect to

external VSS when negative voltage generator is enabled.

For detailed usage please refer to the “Negative Voltage

Generator” section.

HMC981LP3E

v02.1222

ACTIVE BIAS CONTROLLER