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
V
DD
PGND
OUTA
OUTB
SD
OTW
1
3
8
7
6
5
2
4
V
DS
V
DS
08132-017
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
input structure allows for input voltages as high as V
DD
.
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
internally connected to the V
DD
supply and PGND.
When the ADP362x/ADP363x family is disabled, both low-side
gates are held low. An internal impedance is present between
the OUTA/OUTB pins and GND, even when V
DD
is not present;
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
V
EN
SD
08132-018
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.
