Datasheet

IS
PWM
Start new on time
nDIM
UVLO
HYSTERESIS
COMP
REFERENCE
CURRENT
LIMIT
CSH
HSN
LOGIC
HSP
S
R
Q
QB
UVLO
GATE
PGND
VccUVLO
Thermal
Limit
TLIM
V
IN
/25
Standby
Dimming
Reset
Dominant
RCT
LEB
AGND
V
CC
V
CC
V
IN
6.9V LDO
Regulator
OVP
OVP
HYSTERESIS
20 PA
1.24V
800 mV
1.24V
20 PA
1.24V
1.24V
245 mV
LM3429, LM3429-Q1
SNVS616G –APRIL 2009–REVISED MAY 2013 www.ti.com
BLOCK DIAGRAM
Theory of Operation
The LM3429 is an N-channel MosFET (NFET) controller for buck, boost and buck-boost current regulators which
are ideal for driving LED loads. The controller has wide input voltage range allowing for regulation of a variety of
LED loads. The high-side differential current sense, with low adjustable threshold voltage, provides an excellent
method for regulating output current while maintaining high system efficiency. The LM3429 uses a Predictive Off-
time (PRO) control architecture that allows the regulator to be operated using minimal external control loop
compensation, while providing an inherent cycle-by-cycle current limit. The adjustable current sense threshold
provides the capability to amplitude (analog) dim the LED current and the output enable/disable function allows
for PWM dimming using no external components. When designing, the maximum attainable LED current is not
internally limited because the LM3429 is a controller. Instead it is a function of the system operating point,
component choices, and switching frequency allowing the LM3429 to easily provide constant currents up to 5A.
This simple controller contains all the features necessary to implement a high efficiency versatile LED driver.
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Product Folder Links: LM3429 LM3429-Q1