5

Functional description

5.1

Gate driving power supply and UVLO

The STGAP2D is a flexible and compact gate driver with 4 A output current and rail-to-rail outputs. The device

allows implementing either unipolar or bipolar gate driving.

I

S

O

L

A

T

I

O

N

VH_x

GNDISO_x

VDD

GND

INx

GOUT_x

+

VH

VDD

+

VH

+

VL

Unipolar gate driving

Bipolar gate driving

I

S

O

L

A

T

I

O

N

VH_x

GNDISO_x

VDD

GND

INx

GOUT_x

1uF

100nF

VDD

1uF

100nF

1uF

100nF

100nF

1uF

1uF

Undervoltage protection is available on VH_x supply pin. A fixed hysteresis sets the turn-off threshold, thus

avoiding intermittent operation.

pins status.

The VDD and VH_x supply pins must be properly filtered with local bypass capacitors. The use of capacitors with

different values in parallel provides both local storage for impulsive current supply and high-frequency filtering.

We recommend using low-ESR SMT ceramic capacitors for the best filtering performance. A 100 nF ceramic

capacitor must be placed as close as possible to each supply pin, and a second bypass capacitor with value

between 1 μF and 10 μF should be placed close to it.

5.2

Power-up, power-down and safe state

The following conditions define the safe state:

•

GOUT n-channel = ON state

•

GOUT p-channel = high impedance

The device integrates a structure that clamps the driver output to a voltage not higher than SafeClp when VH

voltage is not high enough to actively turn the internal GOUT n-channel on. If VH_x positive supply pin is floating

or not supplied, the GOUT pin is therefore clamped to a voltage smaller than SafeClp.

If the supply voltage VDD of the control section of the device is not supplied, the output is put in safe state and

remains in this condition until the VDD voltage returns to operative conditions.

After power-up of both isolated and low voltage side, the device output state depends on the status of the input

pins.

STGAP2D

Functional description

DS12746 - Rev 3

page 8/22