N-Channel Controller. LM3429 Datasheet
April 30, 2009
N-Channel Controller for Constant Current LED Drivers
The LM3429 is a versatile high voltage LED driver controller.
With the capability to be configured in a Buck, Boost, Buck-
Boost (Flyback), or SEPIC topology, and an input and output
operating voltage rating of 75V, the LM3429 is ideal for illu-
minating LEDs in a very diverse, large family of applications.
Adjustable high-side current sense with a typical sense volt-
age of 100 mV allows for tight regulation of the LED current
with the highest efficiency possible. Output LED current reg-
ulation is based on peak current-mode control with predictive
Off-Time Control. This method of control eases the design of
loop compensation while providing inherent input voltage
The LM3429 includes a high-voltage startup regulator that
operates over a wide input range of 4.5V to 75V. The internal
PWM controller is designed for adjustable switching frequen-
cies of up to 2.0MHz, thus enabling compact solutions. Addi-
tional features include: precision reference, logic compatible
DIM input suitable for fast PWM dimming, cycle-by-cycle cur-
rent limit, and thermal shutdown.
The LM3429 comes in a low profile, thermally efficient TSSOP
EP 14-lead package.
■ VIN range from 4.5V to 75V
■ 2% Internal reference voltage (1.235V)
■ Current sense voltage adjustable from 20 mV
■ High-side current sensing
■ 2Ω MOSFET gate driver
■ Dimming MOSFET gate driver
■ Input under-voltage protection
■ Over-voltage protection
■ Low shutdown current, IQ < 1µA
■ Fast (50kHz) PWM dimming
■ Cycle-by-cycle current limit
■ Programmable switching frequency
■ TSSOP EP 14-lead package
■ LED Drivers
■ Constant-Current Buck-Boost Regulator
■ Constant-Current Boost Regulator
■ Constant-Current Flyback Regulator
■ Constant-Current SEPIC Regulator
■ Thermo-Electric Cooler (Peltier) Driver
Typical Application Circuit
Boost LED Driver
© 2009 National Semiconductor Corporation 300944
14-Lead TSSOP EP
NS Package Number MXA14A
Order Number Spec.
92 Units, Rail
2500 Units, Tape and Reel
Power supply input (4.5V-75V). Bypass with 100nF capacitor to AGND as close to the device as possible
in the circuit board layout.
Compensation: PWM controller error amplifier compensation pin. This pin connects through a series resistor-
capacitor network to AGND.
Current Sense High: Output of the high side sense amplifier and input to the main regulation loop error
Resistor Capacitor Timing: External RC network sets the predictive “off-time” and thus the switching
frequency. The RC network should be placed as close to the device as possible in the circuit board layout.
Analog Ground: The proper place to connect the compensation and timing capacitor returns. This pin should
be connected via the circuit board to the PGND pin through the EP copper circuit board pad.
Over-Voltage Protection sense input: 1.24V threshold with hysteresis that is user programmable by the
selection of the OVP Over-Voltage Lock-Out (OVLO) resistor divider network. If not used connect pin to
Not DIM input: Dual function pin. Primarily used as the Pulse Width Modulation (PWM) input. When driven
with a resistor divider from VIN, this pin also functions as a user programmable VIN Under-Voltage Lock-Out
(UVLO) with 1.24V threshold and programmable hysteresis by the UVLO resistor divider network. The PWM
and UVLO functions can be performed simultaneously.
No connection. Leave this pin open.
Power Ground: GATE and DDRV gate drive ground current return pin. This pin should be connected via the
circuit board to the AGND pin through the EP copper circuit board pad.
Main switching MOSFET gate drive output.
Internal Regulator Bypass: 6.9V low dropout linear regulator output. Bypass with a 2.2 µF–3.3 µF, ceramic
type capacitor to PGND.
Main Switch Current Sense input: This pin is used for current mode control and cycle-by-cycle current limit.
This pin can be tied to the drain of the main N-channel MOSFET switch for
RDS(ON) sensing or tied to a sense resistor installed in the source of the same device.
High Side Sense Positive: LED current sense positive input. An external resistor sets a reference current
flowing into this pin from the programmed high-side sense voltage. Although the current into this pin can be
set to values ranging from 10 µA through 1 mA, a value of 100 µA is recommended. This pin is a virtual
ground whose potential is set by the voltage on the HSN pin.