ADP3629/ADP3630/ADP3631

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THEORY OF OPERATION

The ADP3629/ADP3630/ADP3631 family of dual drivers is

optimized for driving two independent enhancement N-channel

MOSFETs or insulated gate bipolar transistors (IGBTs) in high

switching frequency applications.

These applications require high speed, fast rise and fall times, and

short propagation delays. The capacitive nature of MOSFETs and

IGBTs requires high peak current capability, as well.

VDD

PGND

OUTA

OUTB

SD

OTW

1

3

8

7

6

5

2

4

ADP3629/ADP3630/ADP3631

B

NONINVERTING

INVERTING

A

NONINVERTING

INVERTING

INA,

INA

INB,

INB

Figure 21. Typical Application Circuit

INPUT DRIVE REQUIREMENTS (INA, INA, INB, INB,

AND SD)

The inputs of the ADP3629/ADP3630/ADP3631 are designed

to meet the requirements of modern digital power controllers;

the signals are compatible with 3.3 V logic levels. At the same

The signals applied to the inputs (INA, INA, INB, and INB)

should have steep and clean fronts. It is not recommended that

slow changing signals be applied to drive these inputs because

such signals can result in multiple switching output signals

when the thresholds are crossed, causing damage to the power

MOSFET or IGBT.

An internal pull-down resistor is present at the input, which

guarantees that the power device is off in the event that the

input is left floating.

The SD input has a precision comparator with hysteresis and is

therefore suitable for slow changing signals (such as a scaled-

down output voltage); see the Shutdown (SD) Function section

for more information about this comparator.

LOW-SIDE DRIVERS (OUTA, OUTB)

The ADP3629/ADP3630/ADP3631 family of dual drivers is

designed to drive ground referenced N-channel MOSFETs. The

When the ADP3629/ADP3630/ADP3631 are disabled, both

low-side gates are held low. An internal impedance is present

not present; this feature ensures that the power MOSFET is

normally off when bias voltage is not present.

When interfacing the ADP3629/ADP3630/ADP3631 to exter-

nal MOSFETs, the designer should consider ways to create a

robust design that minimizes stresses on both the driver and

the MOSFETs. These stresses include exceeding the short time

duration voltage ratings on the OUTA and OUTB pins, as well

as on the external MOSFET.

Power MOSFETs are usually selected to have low on resistance to

minimize conduction losses, which usually implies a large input

gate capacitance and gate charge.

SHUTDOWN (SD) FUNCTION

The ADP3629/ADP3630/ADP3631 feature an advanced shut-

down function with accurate thresholds and hysteresis.

The SD signal is an active high signal. An internal pull-up is

present on this pin and, therefore, it is necessary to pull down

the pin externally for the drivers to operate normally.

In some power systems, it is sometimes necessary to provide an

additional overvoltage protection (OVP) or overcurrent protection

(OCP) shutdown signal to turn off the power devices (MOSFETs

or IGBTs) in case of failure of the main controller.

An accurate internal reference is used for the SD comparator so

that it can be used to detect OVP or OCP fault conditions.

AC

INPUT

DC

OUTPUT

+

–

OUTA

PGND

SD

ADP3629/ADP3630/ADP3631

Figure 22. Shutdown Function Used for Redundant OVP