Data Sheet
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3180 • Rev. 1.0.3 14
FAN3180 — Single 2-A Low-Side Driver with 3.3-V LDO
The power dissipated in a gate-drive circuit is
independent of the drive-circuit resistance and is split
proportionately among the resistances present in the
driver, any discrete series resistor present, and the gate
resistance internal to the power switching MOSFET.
Power dissipated in the driver may be estimated using
the following equation:
FETGATE,EXTDRIVEROUT,
DriverOUT,
TOTALPKG
RRR
R
PP
(5)
where:
P
PKG
= power dissipated in the driver package;
R
OUT,DRIVER
= estimated driver impedance derived
from I
OUT
vs. V
OUT
waveforms;
R
EXT
= external series resistance connected between
the driver output and the gate of the MOSFET; and
R
GATE,FET
= resistance internal to the load MOSFET
gate and source connections.
Transitioning from FAN3100
Many applications use a combination of a
microcontroller (MCU) and a gate driver, such as the
FAN3100. In these configurations, an external low-
dropout regulator (LDO) is needed to power the MCU.
The FAN3180 integrates a 3.3-V output voltage
regulator to power the microcontroller or ASICs.
Therefore, systems using the FAN3100 and similar
configurations can transition to the FAN3180 to save
component count, board space, and cost.
The FAN3180 pinout is also such that minimal effort is
needed to transition from designs already using the
FAN3100TSX (the SOT23-5 package option). Four of
the five pins are the same on both devices. The IN-
input (pin 4 on the FAN3100) has been replaced with
3V3 LDO output on the FAN3180.
The following two diagrams show typical application
examples of both the FAN3100 and FAN3180 designs
powering a microcontroller.
IN-
VDD
MCU
PWM
Input
Load
1
4
5
3
2
OUT
IN+
GND
VDD
LDO
3.3V
FAN3100
UVLO
Figure 35. FAN3100TSX with an External LDO to Power a MCU
VDD
MCU
PWM
Input
Load
LDO
3.3V
FAN3180
3V3
1
4
5
3
2
UVLO
LDO
OUT
IN+
GND
VDD
Figure 36. FAN3180TSX (with Integrated LDO) to Power a MCU