The LM3429 is a versatile high voltage N-channel MosFET controller for LED drivers. It can be easily configured in buck, boost, buck-boost and SEPIC topologies. This flexibility, along with an input voltage rating of 75V, makes the LM3429 ideal for illuminating LEDs in a very diverse, large family of applications.
Adjustable high-side current sense voltage allows for tight regulation of the LED current with the highest efficiency possible. The LM3429 uses Predictive Off-time (PRO) control, which is a combination of peak current-mode control and a predictive off-timer. This method of control eases the design of loop compensation while providing inherent input voltage feed-forward compensation.
The LM3429 includes a high-voltage startup regulator that operates over a wide input range of 4.5 V to 75 V. The internal PWM controller is designed for adjustable switching frequencies of up to 2 MHz, thus enabling compact solutions. Additional features include analog dimming, PWM dimming, overvoltage protection, undervoltage lock-out, cycle-by-cycle current limit, and thermal shutdown.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM3429 | HTSSOP (14) | 5.00 mm × 4.40 mm |
LM3429-Q1 |
Changes from G Revision (April 2013) to H Revision
Changes from F Revision (May 2013) to G Revision
PIN | I/O | DESCRIPTION | APPLICATION INFORMATION | |
---|---|---|---|---|
NO. | NAME | |||
1 | VIN | I | Input Voltage | Bypass with 100 nF capacitor to AGND as close to the device as possible in the circuit board layout. |
2 | COMP | I | Compensation | Connect a capacitor to AGND to set compensation. |
3 | CSH | I | Current Sense High | Connect a resistor to AGND to set signal current. For analog dimming, connect current source or potentiometer to AGND (see Analog Dimming section). |
4 | RCT | I | Resistor Capacitor Timing | Connect a resistor from the switch node and a capacitor to AGND to set the switching frequency. |
5 | AGND | GND | Analog Ground | Connect to PGND through the DAP copper circuit board pad to provide proper ground return for CSH, COMP, and RCT. |
6 | OVP | I | Overvoltage Protection | Connect to a resistor divider from the output (VO) or the input to program output overvoltage lockout (OVLO). Turn-off threshold is 1.24 V and hysteresis for turn-on is provided by 20 µA current source. |
7 | nDIM | I | Not DIM input | Connect a PWM signal for dimming as detailed in the PWM Dimming section and/or a resistor divider from VIN to program input undervoltage lockout (UVLO). Turn-on threshold is 1.24 V and hysteresis for turn-off is provided by 20 µA current source. |
8 | NC | No Connection | Leave open. | |
9 | PGND | GND | Power Ground | Connect to AGND through DAP copper pad to provide ground return for GATE. |
10 | GATE | O | Gate Drive Output | Connect to the gate of the external NFET. |
11 | VCC | I | Internal Regulator Output | Bypass with a 2.2 µF–3.3 µF, ceramic capacitor to PGND. |
12 | IS | I | Main Switch Current Sense | Connect to the drain of the main N-channel MosFET switch for RDS-ON sensing or to a sense resistor installed in the source of the same device. |
13 | HSP | I | LED Current Sense Positive | Connect through a series resistor to LED current sense resistor (positive). |
14 | HSN | I | LED Current Sense Negative | Connect through a series resistor to LED current sense resistor (negative). |
DAP (15) | DAP | GND | Thermal pad on bottom of IC | Connect to AGND and PGND. |