The LM3409, LM3409-Q1, LM3409HV, and LM3409HV-Q1 are P-channel MOSFET (PFET) controllers for step-down (buck) current regulators. They offer wide input voltage range, high-side differential current sense with low adjustable threshold voltage and fast output enable/disable function and a thermally enhanced 10-pin, HVSSOP package. These features combine to make the LM3409 family of devices ideal for use as constant current sources for driving LEDs where forward currents up to 5 A are easily achievable.
The LM3409 devices use constant off-time (COFT) control to regulate an accurate constant current without the need for external control loop compensation. Analog and PWM dimming are easy to implement and result in a highly linear dimming range with excellent achievable contrast ratios. Programmable UVLO, low-power shutdown, and thermal shutdown complete the feature set.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM3409 | HVSSOP (10) | 3.00 mm × 3.00 mm |
PDIP (14) | 19.177 mm × 6.35 mm | |
LM3409-Q1 | HVSSOP (10) | 3.00 mm × 3.00 mm |
LM3409HV | ||
LM3409HV-Q1 |
Changes from K Revision (July 2014) to L Revision
Changes from J Revision (May 2013) to K Revision
Changes from I Revision (May 2013) to J Revision
PIN | DESCRIPTION | ||
---|---|---|---|
NAME | PDIP | HVSSOP | |
UVLO | 1 | 1 | Input undervoltage lockout. Connect to a resistor divider from VIN and GND. Turn-on threshold is 1.24 V and hysteresis for turnoff is provided by a 22 µA current source. |
IADJ | 3 | 2 | Analog LED current adjust. Apply a voltage from 0 to 1.24 V, connect a resistor to GND, or leave open to set the current sense threshold voltage. |
EN | 4 | 3 | Logic level enable and PWM dimming. Apply a voltage >1.74 V to enable device, a PWM signal to dim, or a voltage < 0.5 V for low-power shutdown. |
COFF | 5 | 4 | Off-time programming. Connect resistor from VO, capacitor to GND to set off-time. |
GND | 6 | 5 | Connect to system ground. |
PGATE | 9 | 6 | Gate drive. Connect to gate of external P-channel MOSFET. |
CSN | 10 | 7 | Negative current sense. Connect to negative side of sense resistor. |
CSP | 11 | 8 | Positive current sense. Connect to positive side of sense resistor (also to VIN). |
VCC | 12 | 9 | VIN– referenced linear regulator output. Connect at least a 1-µF ceramic capacitor to VIN. The regulator provides power for the P-channel MOSFET drive. |
VIN | 14 | 10 | Input voltage. Connect to the input voltage. |
Thermal pad | — | Connect to GND pin. Place 4 to 6 vias from thermal pad to GND plane. |