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LM3405AXMK

Texas Instruments · LED Drivers · TSOT-23-6L

LM3405AXMK from Texas Instruments, in a TSOT-23-6L. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 BOOST output Boost voltage that drives the NMOS output switch, with a bootstrap capacitor connected between the BOOST and SW pins.
2 GND power_in Signal and power ground pin; the bottom resistor of the feedback network should be placed as close as possible to this pin.
3 FB input Feedback pin; connect FB to the LED string cathode and an external resistor to ground to set the LED current (0.205-V reference per the datasheet description).
4 EN/DIM input Enable control input where logic high enables operation and a periodic PWM square wave sets LED brightness; do not let this pin float or exceed VIN + 0.3 V.
5 VIN power_in Input supply voltage with a 3 V to 22 V operating range; connect a bypass capacitor locally from this pin to GND.
6 SW output Switch pin that connects to the inductor, catch diode, and bootstrap capacitor.

Key specifications

Parameter Value
Manufacturer Texas Instruments
Package TSOT-23-6L
Category LED Drivers
Pins 6

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Feedback voltage VFB 0.188 0.205 0.22 V 5
Feedback input bias current IFB 10 250 nA Sink/source 5
Undervoltage lockout UVLO 2.74 2.95 V VIN Rising 5
Undervoltage lockout UVLO 1.9 2.3 V VIN Falling 5
Switching frequency fSW 1.2 1.6 1.9 MHz 5
Maximum duty cycle DMAX 85 94 % VFB = 0 V 5
Switch ON resistance (SOT package) RDS(ON) 300 600 mΩ SOT (VBOOST - VSW = 3 V) 5
Switch current limit ICL 1.2 2 2.8 A VBOOST - VSW = 3 V, VIN = 3 V 5
Quiescent current (switching) IQ 1.8 2.8 mA Switching, VFB = 0.195 V 5
Enable threshold voltage VEN/DIM_TH 1.8 V VEN/DIM Rising 5
Shutdown threshold voltage VEN/DIM_TH 0.4 V VEN/DIM Falling 5
Input supply voltage VIN -0.5 24 V 4
SW voltage -0.5 24 V 4
Boost voltage -0.5 30 V 4
Boost to SW voltage -0.5 6 V 4
FB voltage -0.5 3 V 4
EN/DIM voltage -0.5 V 4
Junction temperature TJ 150 °C 4
Storage temperature Tstg -65 150 °C 4
VIN input voltage VIN 3 22 V 4
EN/DIM voltage 0 V 4
Boost to SW voltage 2.5 5.5 V 4
Junction temperature TJ -40 125 °C 4
LED current ILED 400 mA SOT package 4
Junction-to-ambient thermal resistance RθJA 182.9 °C/W SOT (DDC) package 5
Junction-to-case (top) thermal resistance RθJC(top) 53.4 °C/W SOT (DDC) package 5
Junction-to-board thermal resistance RθJB 28.1 °C/W SOT (DDC) package 5
Junction-to-top characterization parameter ψJT 1.2 °C/W SOT (DDC) package 5
Junction-to-board characterization parameter ψJB 27.7 °C/W SOT (DDC) package 5

CAD (KiCad official)

  • Symbol: LM3405AXMK
  • Footprint: Package_TO_SOT_SMD:TSOT-23-6
  • 3D model: TSOT-23-6L (KiCad packages3D, STEP)
  • 3D model files: lm3405axmk-etched.step / lm3405axmk-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); lm3405axmk.step / lm3405axmk.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Texas Instruments datasheet (37 pp, sha256 6ffca81b353b1a67, retrieved 2026-10-18, tier: lcsc)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF