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Texas Instruments LM3405AXMKX/NOPB
- Part No.:
- LM3405AXMKX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LM3405AXMKX/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 1A TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:3,261
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Product details
Overview
LM3405AXMKX/NOPB from Texas Instruments is a 1.6-MHz, 1-A constant-current buck LED driver IC with internal compensation, designed for high-efficiency series LED string control in space-constrained lighting applications. It features a 0.205-V feedback reference, 300-mΩ NMOS switch, EN/DIM pin for PWM dimming, and operates from 3 V to 22 V input. It drives up to five 3.7-V HB-LEDs at 1 A in MSOP-PowerPAD™ package.
For engineers reviewing the LM3405AXMKX/NOPB datasheet, LM3405AXMKX/NOPB pinout, LM3405AXMKX/NOPB application, or LM3405AXMKX/NOPB equivalent, key selection considerations include its fixed 1.6-MHz switching frequency, internal current-mode compensation, thermal shutdown behavior, and precise 0.205-V FB reference for accurate LED current setting via external resistor.
Technical Context
The LM3405AXMKX/NOPB implements current-mode PWM control with an internally set 1.6-MHz oscillator, enabling stable regulation using small ceramic capacitors and low-profile inductors. Its cycle-by-cycle current limit (typ. 2 A) and overcurrent protection (FB threshold = 328 mV) operate independently of loop dynamics to safeguard the internal NMOS switch.
Feedback is referenced to a trimmed 0.205-V bandgap voltage with ±1.5% tolerance over –40°C to +125°C, and line regulation is 0.01%/V. The EN/DIM pin supports both logic-enable functionality (1.8-V turn-on threshold) and 100 Hz–5 kHz PWM dimming with ~100 µs startup delay to full current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VFB | 0.205 V ±1.5% - Sets LED current precisely via external RSET; enables <1% current error at 1 A with 0.2 Ω resistor. |
| fSW | 1.6 MHz (min 1.2 / max 1.9 MHz) - Enables use of ≤2.2 µH inductors and 10–22 µF ceramic output caps; reduces EMI filtering burden. |
| RDS(ON) | 360 mΩ (max 700 mΩ) - Limits conduction loss to ≤0.36 W at 1 A; defines thermal design margin in MSOP-PowerPAD™ package. |
| ICL | 2 A (typ) cycle-by-cycle limit - Protects internal switch during short-circuit or cold-start transients without latch-off. |
| UVLO Threshold | 2.95 V rising / 2.3 V falling - Prevents erratic startup below 3 V; 440 mV hysteresis avoids oscillation during brownout. |
| IQ (shutdown) | 0.3 µA at VIN = 5 V - Enables ultra-low-power standby in battery-powered flashlights and emergency lighting. |
| TJ Range | –40°C to +125°C - Supports operation in enclosed industrial luminaires and automotive under-hood ambient conditions. |
Pinout & Package
LM3405AXMKX/NOPB is packaged in an 8-pin MSOP-PowerPAD™ (DGN) with exposed thermal pad (DAP), measuring 3.00 mm × 3.00 mm. The DAP must be soldered to PCB ground plane for thermal performance (RθJB = 38.9°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (Pin 4) | Bootstrap gate drive node | Supplies >2.5 V above SW to fully enhance internal NMOS; requires external 0.1 µF ceramic capacitor to SW. |
| GND (Pins 2, 7) | Signal and power ground | Dual ground pins reduce ground bounce; FB resistor bottom must connect directly to Pin 2 for accuracy. |
| FB (Pin 1) | Current-sense feedback input | Sinks 250 nA max; connects to LED string cathode; regulates current by holding voltage at 0.205 V. |
| EN/DIM (Pin 8) | Enable and PWM dimming input | Logic-compatible (0.4 V/1.8 V thresholds); toggling at 100 Hz–5 kHz controls average LED brightness. |
| VIN (Pin 6) | Main input supply | Accepts 3–22 V; requires local 1–10 µF ceramic bypass cap to GND; UVLO active below 2.3 V. |
| SW (Pin 5) | Switch node | Connects to inductor, catch diode anode, and BOOST capacitor; swings from GND to VIN − ILED×RDS(ON). |
Key Features
| Feature | Design Value |
|---|---|
| Internally compensated current-mode control | Eliminates external compensation network; ensures stable loop response across 0.2–1 A load and 3–22 V input range. |
| 1.6-MHz fixed-frequency PWM | Reduces inductor size to ≤2.2 µH and output capacitance to ≤22 µF; simplifies EMI filter design vs. lower-frequency alternatives. |
| 0.205-V precision feedback reference | Enables ±3% LED current accuracy with standard 1% RSET; minimizes power loss in current-setting resistor. |
| Thermal shutdown (165°C) | Disables SW until junction cools to ~150°C; protects against sustained overload in enclosed fixtures without airflow. |
| 40-nA shutdown quiescent current | Extends battery life in portable LED flashlights; allows direct connection of EN/DIM to microcontroller GPIO without pull-down. |
Applications
| Architectural LED Strips | Industrial Machine Vision Lighting |
|---|---|
|
Use Scenario: Constant-brightness linear LED arrays mounted on aluminum extrusions for retail display backlighting. IC Role / Device Role / Timing Role: Primary constant-current regulator controlling 4-series white LEDs (14.8 V total VF) from 24-V DC rail. Use Value: 1.6-MHz switching enables compact 2.2-µH shielded inductor; internal compensation eliminates tuning effort; thermal pad ensures <65°C case temp at 1 A. |
Use Scenario: High-intensity strobed illumination synchronized to camera exposure in automated inspection systems. IC Role / Device Role / Timing Role: Fast-response current source triggered by EN/DIM pulse to deliver precise 1-A LED bursts within 100 µs. Use Value: 100 µs enable-to-full-current delay matches typical camera shutter timing; 2-A current limit prevents damage during sync faults. |
| Portable LED Flashlights | Smart LED Lightbulbs |
|
Use Scenario: Single-cell Li-ion (2.7–4.2 V) powered tactical flashlight requiring regulated 1-A output across battery discharge curve. IC Role / Device Role / Timing Role: Buck LED driver with UVLO hysteresis preventing flicker near end-of-life; EN/DIM used for mode switching. Use Value: 0.3 µA shutdown current preserves battery shelf life; 3-V min input supports operation down to 2.95-V UVLO rising threshold. |
Use Scenario: Retrofit A19 bulb with integrated AC/DC converter and 5-LED string driven from 12–18 V intermediate bus. IC Role / Device Role / Timing Role: Secondary-stage constant-current controller ensuring consistent lumen output despite input ripple. Use Value: Internal compensation maintains stability with low-ESR ceramic caps; 22-V max input accommodates transient spikes on 15-V bus. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current buck LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3405AMKX/NOPB | SOT-23-6 package (2.9 × 1.6 mm); lower thermal capability (RθJA = 182.9°C/W); rated for 400 mA continuous. | Used where board area is critical but power dissipation is low (e.g., single-LED indicator). | Select when footprint is constrained and LED current ≤400 mA; not suitable for 1-A thermal loads. |
| TPS61061DRVR | Boost topology; 28-V output capability; 0.5-A max output; integrated 0.5-Ω switch; no BOOST pin required. | Preferred for driving 1–3 LEDs from single-cell Li-ion where VOUT > VIN (e.g., 3.3-V rail → 10-V string). | Choose for boost applications or when input voltage is always below LED string VF; not a drop-in replacement. |
Compared with LM3405AXMKX/NOPB, the LM3405AMKX/NOPB trades thermal performance for smaller size, while the TPS61061DRVR changes topology entirely-making it suitable only when boost conversion is needed and 1-A output is unnecessary.
Availability
LM3405AXMKX/NOPB is available at Aetrix Electronics and suitable for industrial lighting, portable LED flashlights, and smart lightbulb production requiring stable component supply and long-term lifecycle support.
Supply support for LM3405AXMKX/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management ICs, with leadership in high-reliability industrial and automotive solutions.
The LM3405A product line delivers compact, thermally robust constant-current LED drivers optimized for efficiency-critical, space-constrained lighting applications from portable to architectural scale.
FAQ
What is the maximum LED string voltage supported by LM3405AXMKX/NOPB?
The LM3405AXMKX/NOPB supports LED strings up to approximately 18.5 V, calculated as VIN(max) − VSW(drop) − VD1, where VIN(max) = 22 V, VSW drop ≈ 0.36 V at 1 A, and VD1 ≈ 0.7 V. This enables driving five 3.7-V HB-LEDs (18.5 V total) from a 22-V supply. Exceeding this limits risks regulation loss or thermal overload.
Can LM3405AXMKX/NOPB operate from a 3.3-V input to drive a single 3-V LED?
Yes, LM3405AXMKX/NOPB can operate from 3.3 V, but only if the LED forward voltage plus diode drop remains below VIN minus switch and diode losses. At 3.3 V input and 3 V LED VF, headroom is marginal (~0.3 V), risking dropout. For reliable operation, use ≥4 V input or verify duty cycle >90% and thermal rise under load per the datasheet's efficiency curves.
How does the EN/DIM pin function in shutdown versus PWM dimming modes?
At EN/DIM < 0.4 V, LM3405AXMKX/NOPB enters shutdown with 0.3 µA IQ. At 0.4–1.8 V, the device remains disabled but not fully asleep. At >1.8 V DC, it enables steady-state LED current. For PWM dimming, a square wave (100 Hz–5 kHz) applied to EN/DIM toggles full current on/off, with ~100 µs delay to reach 1 A each time-enabling precise brightness control without analog current scaling.
What is the purpose of the BOOST pin, and what capacitor value is recommended?
The BOOST pin supplies gate drive voltage to the internal NMOS switch via a bootstrap capacitor tied to SW. A 0.1 µF X7R ceramic capacitor (6.3 V rating) is recommended between BOOST and SW. This ensures sufficient gate voltage (>2.5 V above SW) for low RDS(ON) and efficient switching; larger values offer no benefit and may slow startup.
Does LM3405AXMKX/NOPB require an external Schottky diode, and why?
Yes, LM3405AXMKX/NOPB requires an external Schottky catch diode (e.g., 1N5819, 40 V, 1 A) connected from SW to VOUT. It provides the freewheeling path for inductor current during switch off-time, preventing negative voltage spikes and enabling proper regulation. Standard PN diodes introduce excessive VF loss and slow recovery, degrading efficiency and thermal performance.
LM3405AXMKX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SOT-23-6 Thin, TSOT-23-6
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 3V
- Voltage - Supply (Max):
- 22V
- Voltage - Output:
- -
- Current - Output / Channel:
- 1A
- Frequency:
- 1.6MHz
- Dimming:
- PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-6
LM3405AXMKX/NOPB FAQ
1.How can I place an order for LM3405AXMKX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3405AXMKX/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM3405AXMKX/NOPB reliable?
The price and inventory of LM3405AXMKX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3405AXMKX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3405AXMKX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3405AXMKX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3405AXMKX/NOPB?
LM3405AXMKX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3405AXMKX/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM3405AXMKX/NOPB?
For technical support, including LM3405AXMKX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3405AXMKX/NOPB requirements.
6.How does Aetrix verify that LM3405AXMKX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3405AXMKX/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM3405AXMKX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3405AXMKX/NOPB?
All LM3405AXMKX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3405AXMKX/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM3405AXMKX/NOPB part is unused and in its original packaging.
Return procedure for LM3405AXMKX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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