LM3405AXMKE/NOPB - 1.6MHz 1A Buck LED Driver TSOT-23-6 | TI
MPN: LM3405AXMKE/NOPB ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.42 | $1.42 |
| 10 | $1.21 | $12.10 |
| 100 | $0.95 | $95.00 |
| 500 | $0.78 | $390.00 |
| 1,000 | $0.66 | $660.00 |
LM3405AXMKE/NOPB Overview
A buck LED driver is a switch-mode DC-DC converter that steps a higher DC bus voltage down to the forward voltage required by an LED string, while actively regulating the current through the string. Compared with linear current sinks, buck regulators achieve much higher efficiency (typically 90%+) because excess voltage is not dissipated as heat. Buck LED drivers sit within the broader hierarchy of LED driver ICs -> lighting power management -> power management ICs -> semiconductors, and they are the workhorse topology for indoor and outdoor solid-state lighting where the input rail exceeds the LED string forward voltage.
Key features of the LM3405AXMKE/NOPB include 1.6 MHz PWM switching with internal MOSFET switches, internal compensation that eliminates the external compensation network, a 0.205 V feedback reference for high-efficiency current sensing, an EN/DIM pin supporting both enable and PWM dimming, and built-in thermal shutdown. The TSOT-23-6 footprint measures approximately 2.9 mm x 1.6 mm, making the device one of the smallest 1 A buck LED drivers in TI's PowerWise family. Cycle-by-cycle current limit and over-temperature protection safeguard the IC and LEDs during fault conditions.
Architecturally, the LM3405A uses a peak current-mode control loop with an internal 1.6 MHz oscillator and an integrated N-channel MOSFET high-side switch. Internal compensation simplifies the BOM to an input capacitor, an inductor, a Schottky rectifier, a sense resistor, and a feedback resistor divider. The 0.205 V reference reduces the sense-resistor IR drop by 3-5x versus the older LM3405 (0.2 V reference), cutting wasted power and improving efficiency in high-current strings.
Typical applications include MR16 LED spotlights, architectural and decorative LED lighting, automotive interior and courtesy lighting, display backlight drivers, and constant-current LED strips. The wide 3 V to 15 V input range covers both 5 V and 12 V systems as well as single-cell Li-Ion battery packs. PWM dimming via the EN/DIM pin supports analog-style brightness control with ratios up to 1000:1.
When designing with the LM3405AXMKE/NOPB, choose a low-ESR ceramic input capacitor rated for at least 20 V and a Schottky diode with reverse voltage greater than VIN. The sense resistor value sets LED current via ILED = 0.205 V / RSENSE; verify PCB trace Kelvin connection to the FB pin to avoid ground-loop errors. The exposed DDC package thermal pad must be soldered to a copper pour for rated performance.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for LM3405AXMKE/NOPB — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LM3405AXMKE/NOPB (same form factor and footprint) — differing in Input Voltage Range, MSL Level, Switching Frequency, Topology.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LM3405AXMK/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM3405AXMKX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM3405AMKE/NOPB
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LM3405A-MKE/NOPB
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LM3405AXMKE/NOPB Maximum Ratings & Electrical Characteristics
| Topology | Step-Down (Buck) |
| Number of Outputs | 1 |
| Maximum LED Current | 1 A |
| Input Voltage Range | 3 V to 15 V (5 V/9 V/12 V/15 V nominal rails supported) |
| Switching Frequency | 1.6 MHz (typical) |
| Feedback Reference Voltage | 0.205 V |
| Control Method | Constant Current, PWM Dimming |
| Internal Switch | Yes (integrated MOSFET) |
| Internal Compensation | Yes |
| Dimming Interface | EN/DIM pin (PWM dimming + enable) |
| Operating Temperature Range | -40 C to +125 C |
| Package | TSOT-23-6 (DDC), 6 pins |
| Mounting Type | Surface Mount |
| Thermal Protection | Thermal Shutdown |
| MSL Level | 1 (per TI product page) |
| RoHS Status | Compliant |
LM3405AXMKE/NOPB Pin Configuration
| Pin 1 | EN/DIM — Enable and PWM dimming input (logic high = on; PWM signal for dimming) |
| Pin 2 | GND — Ground return for the IC and the LED current-sense path |
| Pin 3 | FB — Feedback input from low-side sense resistor; threshold 0.205 V sets ILED |
| Pin 4 | BST — Bootstrap capacitor node for the internal high-side gate driver |
| Pin 5 | VIN — Input supply voltage (3 V to 15 V); decouple with 10 uF ceramic to GND |
| Pin 6 | SW — Switch node - internal N-FET drain; connects to inductor and Schottky cathode |
Typical Applications
LM3405AXMKE/NOPB is suitable for 7 applications: MR16 LED Spotlight Driver, Architectural and Decorative LED Lighting, Automotive Interior LED Lighting, LCD Display Backlight Driver, Portable LED Flashlight and Torch, Industrial Sign and Channel Letter Lighting, USB-Powered LED Task Light.
MR16 LED Spotlight Driver
The LM3405AXMKE/NOPB is a near-ideal driver for MR16 LED replacement lamps because its 3 V to 15 V input range covers both 12 V AC-DC and 12 V DC electronic transformer outputs, while the 1.6 MHz switching frequency stays above the AM band and allows a tiny chip inductor that fits in the MR16 form factor. The 1 A continuous rating supports 5 W to 7 W class LED MR16 lamps using a 3x or 4x white-LED series string. The 0.205 V VREF minimizes RSENSE dissipation - critical in the thermally-constrained MR16 enclosure. The EN/DIM pin accepts a 1 kHz PWM dimming signal from a standard TRIAC dimmer interface, enabling 100:1 dimming. The TSOT-23-6 footprint occupies just 2.9 mm x 1.6 mm on the lamp PCB, leaving room for the bridge rectifier and small-signal components.
Recommended
Architectural and Decorative LED Lighting
Architectural LED strips and decorative fixtures benefit from the LM3405AXMKE/NOPB's compact TSOT-23-6 package, internal compensation (no external RC loop network), and 1 A constant-current output. With a 12 V or 24 V input and a 3x white-LED string, the device delivers 3 W of regulated LED power at > 90% efficiency, keeping the driver PCB small enough to fit inside junction boxes and track-light heads. PWM dimming via EN/DIM at 200 Hz to 1 kHz integrates with standard 0-10 V or DALI dimmer wall plates using a small interface circuit. The 0.205 V low-side feedback reference reduces RSENSE power loss versus the older LM3405 by approximately 5-10%, which is meaningful at the 1 A current level. The exposed DDC pad provides adequate thermal dissipation for 1 A continuous operation in enclosed fixtures.
Recommended
Automotive Interior LED Lighting
Interior automotive LED applications - dome lights, map lights, ambient strip lighting, and courtesy lamps - are well-served by the LM3405AXMKE/NOPB when designed within its 3 V to 15 V input envelope (suitable for 12 V battery systems with load-dump margin managed externally). The 1 A continuous LED current handles clusters of mid-power LEDs in parallel strings, and the 1.6 MHz switching frequency avoids AM-band interference. PWM dimming at 100-200 Hz through the EN/DIM pin supports smooth brightness transitions typical of premium interior lighting. The -40 C to +125 C operating temperature range covers the automotive under-dash and cabin environment. Note that for AEC-Q100 qualification, the AEC-Q100 grade version (LM3405A-Q1 family) should be selected; the standard LM3405AXMKE/NOPB is rated for industrial/commercial use only.
Recommended
LCD Display Backlight Driver
Small-to-medium LCD display backlights using edge-lit LED arrays can use the LM3405AXMKE/NOPB as a compact constant-current source. The 1 A output current drives a string of 3 to 6 white LEDs in series (typical 9-21 V total Vf) with VIN = 12 V, providing uniform backlight brightness across the panel. The 1.6 MHz switching rate is well above the LCD refresh frequency, eliminating visible flicker or beat-frequency artifacts. The EN/DIM pin accepts a PWM signal from the display controller, allowing direct brightness control synchronized with ambient-light sensor feedback. The TSOT-23-6 footprint fits within the narrow bezel of small LCD modules, and the internal compensation eliminates the loop-stability design effort typical of older buck LED controllers, reducing time-to-market for display products.
Recommended
Portable LED Flashlight and Torch
Handheld LED flashlights and torches powered by a single Li-Ion cell (3.0 V to 4.2 V) or 3x AA batteries are an excellent application for the LM3405AXMKE/NOPB. The 3 V minimum input voltage allows direct connection to a single Li-Ion cell, while the 1 A output current drives a 3 W class white LED. The 1.6 MHz switching frequency allows a 4.7 uH chip inductor, and the high efficiency (>85% at typical load) extends battery runtime by 30-50% versus linear current regulators. The EN/DIM pin supports simple momentary push-button on/off and brightness-mode switching. Thermal shutdown protects the IC during accidental shorts or excessive ambient temperature. With a 6-pin TSOT-23-6 package, the entire driver circuit fits on a 10 mm x 10 mm PCB, ideal for compact flashlight form factors.
Recommended
Industrial Sign and Channel Letter Lighting
Channel-letter signs, exit signs, and industrial indicator panels use the LM3405AXMKE/NOPB for its robust 15 V input rating (covering 12 V industrial bus) and 1 A current capability. A typical channel-letter module drives 3 to 6 high-brightness LEDs in series at 350 mA to 700 mA; one LM3405AXMKE/NOPB per string provides individual constant-current regulation, which is critical for uniform brightness across large signs where LED forward voltages vary. The internal MOSFET and internal compensation minimize the BOM (one IC, one inductor, one Schottky, two caps, one sense resistor), keeping the per-string cost low enough for large sign installations. The -40 C to +125 C operating range supports outdoor enclosed signage. PWM dimming via EN/DIM enables daylight-sensor-driven brightness control for energy savings.
Recommended
USB-Powered LED Task Light
USB-powered task lights, reading lamps, and under-monitor LED bars use the LM3405AXMKE/NOPB driven from a 5 V USB rail. With VIN = 5 V, the device drives a 1x or 2x white-LED string at up to 1 A, providing 3 W to 6 W of LED power - enough for a focused task light. The 1.6 MHz switching frequency allows a 2.2 uH to 4.7 uH chip inductor, and the 90%+ efficiency means very little power is wasted as heat in the small USB-powered enclosure. The EN/DIM pin connects directly to a USB GPIO or push-button for on/off and brightness control. The TSOT-23-6 package plus 5 external components fits on a PCB under 15 mm x 10 mm. The 0.205 V low-side VREF keeps the sense resistor small (0.2 ohm for 1 A) and its power dissipation under 0.3 W, eliminating the need for a large sense-resistor footprint.
Recommended
Recommended Products Summary
Engineering reference data for LM3405AXMKE/NOPB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM3405AXMK/NOPB | LM3405AXMKX/NOPB | LM3405AMKE/NOPB |
|---|---|---|---|---|
| Package | TSOT-23-6 (DDC) | TSOT-23-6 (DDC) - same | TSOT-23-6 (DDC) - same | TSOT-23-6 (DDC) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 1 A | 1 A | 1 A | 1 A |
| Input Voltage Range | 3 V to 15 V | 3 V to 15 V | 3 V to 15 V | 3 V to 15 V |
| Switching Frequency | 1.6 MHz | 1.6 MHz | 1.6 MHz | 1.6 MHz |
| Feedback Reference (VREF) | 0.205 V | 0.205 V | 0.205 V | 0.2 V (-2.5%) |
| Reel Quantity | 3,000 (E suffix) | 1,000 (K suffix) | 3,000 (KX suffix, ext temp) | 3,000 |
| PWM Dimming | Yes (EN/DIM) | Yes (EN/DIM) | Yes (EN/DIM) | Yes (EN/DIM) |
| Unit Price (qty 1, USD, as of 2026-10-08) | $1.42 | $1.40 | $1.50 | $1.10 |
Key Differentiators
- Lower VREF for higher efficiency (vs LM3405AMKE/NOPB)
- Internal compensation eliminates design effort (vs LM3405AXMK/NOPB)
- Compact TSOT-23-6 enables smallest 1 A buck LED designs (vs LM3405AXMK/NOPB (same package, different reel qty))
Design Notes
At 1 A output and VIN = 12 V, VLED = 9 V (3x white LED), power dissipation in the LM3405AXMKE/NOPB is approximately 0.35 W (3 V x 1 A x ~12% losses) - well within the TSOT-23-6 thermal limit when the exposed DDC pad is soldered to a copper pour of at least 100 mm^2. Estimated: at theta_JA = 80 C/W on a 1-oz 4-layer JEDEC test board, junction temperature rise is roughly 28 C above ambient at full load. For VIN = 15 V and VLED = 3 V, dissipation climbs to ~0.8 W, requiring a larger thermal pad. Avoid placing the IC adjacent to the LED string, which can be a significant local heat source.
Layout is critical for the LM3405AXMKE/NOPB. Place the 10 uF input ceramic capacitor within 5 mm of the VIN (pin 5) and GND (pin 2) pins with wide, direct copper pours. The SW node (pin 6) trace should be short and wide to minimize ringing; surround it with a ground copper pour on the top layer to reduce radiated EMI at 1.6 MHz. Route the FB trace as a Kelvin connection directly to the sense-resistor pads, avoiding shared ground paths with the high-current LED return. The exposed DDC thermal pad must be soldered to a bottom-layer copper pour with at least 4 thermal vias to the top-layer ground pour for rated 1 A performance.
Do not exceed the 15 V absolute maximum input voltage - even brief transients above 18 V from a loosely-regulated 12 V automotive bus can permanently damage the IC. Always place a Schottky rectifier (rated >= 1 A and >= 20 V reverse voltage, e.g. BSS84 or SS14) in parallel with the internal N-FET low-side path, with the cathode at SW and anode at GND. Do not omit the bootstrap capacitor (typically 0.1 uF from BST to SW); without it, the high-side gate drive will be too weak and efficiency will collapse. When using PWM dimming, do not exceed 1 kHz - higher frequencies can interact with the converter's internal loop and cause audible noise or instability.
The LM3405AXMKE/NOPB's 1.6 MHz fundamental switching frequency is above the AM broadcast band but its harmonics can still radiate. Place a small ferrite bead (600 ohm at 100 MHz) on the input power lead for conducted EMI suppression, and keep the SW node copper area minimal. The output LED string wiring can act as an antenna - use twisted-pair or shielded cable if the wiring exceeds 50 mm. For CISPR 15 / FCC Part 15 Class B compliance in commercial lighting products, add a pi-filter (10 uF + ferrite + 10 uF) on the input. The exposed DDC pad ground connection provides a low-impedance return path that reduces common-mode emissions.
Compliance Information
RoHS and REACH compliant per TI product page. Not AEC-Q100 qualified - choose LM3405A-Q1 family for automotive applications. Halogen-free per TI's standard PowerWise family materials declaration.
