ADP3623/ADP3624/ADP3625/ADP3633/ADP3634/ADP3635

Rev. A | Page 12 of 16

THEORY OF OPERATION

The ADP362x/ADP363x 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, as

well as short propagation delays. The capacitive nature of the

aforementioned gated devices requires high peak current

capability as well.

VDD

PGND

OUTA

OUTB

SD

OTW

1

3

8

7

6

5

2

4

ADP3623/ADP3624/ADP3625

ADP3633/ADP3634/ADP3635

B

NONINVERTING

INVERTING

A

NONINVERTING

INVERTING

INA,

INA

INB,

INB

Figure 21. Typical Application Circuit

INPUT DRIVE REQUIREMENTS (INA, INA, INB,

The ADP362x/ADP363x family inputs are designed to meet the

requirements of modern digital power controllers; the signals

are compatible with 3.3 V logic levels. At the same time, the

The signals applied to the inputs (INA,

INB,

AND SD)

INA, INB, and

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

INB)

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

apply slow changing signals to drive these inputs because they

can result in multiple switching 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.

Shutdown (SD) Function section

for more details on this comparator.

LOW-SIDE DRIVERS (OUTA, OUTB)

The ADP362x/ADP363x family of dual drivers is designed to

drive ground referenced N-channel MOSFETs. The bias is

When the ADP362x/ADP363x family is disabled, both low-side

gates are held low. An internal impedance is present between

this feature ensures that the power MOSFET is normally off

when bias voltage is not present.

When interfacing the ADP362x/ADP363x family to external

MOSFETs, the designer should consider ways to make 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 the external MOSFET.

Power MOSFETs are usually selected to have a low on resistance

to minimize conduction losses, which usually implies a large

input gate capacitance and gate charge.

SHUTDOWN (SD) FUNCTION

The ADP362x/ADP363x family features an advanced shutdown

function, with accurate threshold 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 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

ADP3623/ADP3624/ADP3625

ADP3633/ADP3634/ADP3635

Figure 22. Shutdown Function Used for Redundant OVP

OVERTEMPERATURE PROTECTIONS

The ADP362x/ADP363x family provides two levels of

overtemperature protections:

•

Overtemperature warning (OTW)

•

Overtemperature shutdown

The overtemperature warning is an open-drain logic signal and

is active low. In normal operation, when no thermal warning is

present, the signal is high, whereas when the warning threshold

is crossed, the signal is pulled low.