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Texas Instruments LM3405AXMK/NOPB
- Part No.:
- LM3405AXMK/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LM3405AXMK/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 1A TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:7,357
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Product details
Overview
LM3405AXMK/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 strings in compact SOT-6 packaging. It operates from 3 V to 22 V input, delivers precise 0.205-V feedback reference for current setting via external resistor, and integrates a 300-mΩ NMOS switch for driving up to five 3.7-V HB LEDs at full 1 A in industrial lighting and flashlight applications.
For engineers reviewing the LM3405AXMK/NOPB datasheet, LM3405AXMK/NOPB pinout, LM3405AXMK/NOPB application, or LM3405AXMK/NOPB equivalent, key selection considerations include its fixed 1.6-MHz switching frequency enabling small magnetics, EN/DIM-controlled PWM dimming (100 Hz–5 kHz), 40-nA shutdown current, cycle-by-cycle current limit, and thermal shutdown protection - all validated for SOT-6 package operation up to 125°C junction temperature.
Technical Context
The LM3405AXMK/NOPB implements current-mode control with internal compensation, eliminating external loop compensation components. Its 1.6-MHz oscillator enables use of sub-2.2-µH inductors and ceramic output capacitors while maintaining stable regulation across 3 V–22 V input and 0.2 A–1 A LED current range.
It uses a bootstrap gate drive architecture where BOOST voltage (2.5 V–5.5 V above SW) controls the internal NMOS switch; feedback is taken directly from the LED string cathode at FB pin, referenced to a trimmed 0.205-V internal bandgap. UVLO (2.74 V rising / 2.3 V falling) and overcurrent protection (328 mV FB threshold) provide robust system-level fault handling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3 V to 22 V - supports wide-input industrial and automotive LED systems without pre-regulation |
| Switching Frequency | 1.6 MHz (typ) - enables use of <2.2 µH inductors and low-ESR ceramic capacitors |
| Feedback Voltage (VFB) | 0.205 V (typ) - sets LED current via external resistor (IF = 0.205 V / R1); minimizes power loss in sense network |
| RDS(ON) | 300 mΩ (typ) - limits conduction loss at 1 A; requires thermal design for SOT-6 package (RθJA = 182.9°C/W) |
| Shutdown Current | 0.3 µA (typ at VIN = 5 V) - enables ultra-low-power off-state in battery-powered flashlights |
| EN/DIM Threshold | 1.8 V enable / 0.4 V disable - supports direct connection to microcontroller GPIO or logic-level PWM signals |
| UVLO Hysteresis | 0.44 V - prevents oscillation during brown-out conditions with non-monotonic input ramps |
Pinout & Package
LM3405AXMK/NOPB is housed in a 6-pin SOT-6 (DDC) package measuring 2.90 mm × 1.60 mm, optimized for space-constrained LED modules. Thermal performance relies on PCB copper area under the exposed pad (GND-connected).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply | Primary DC input (3–22 V); requires local 1-µF ceramic bypass to GND |
| EN/DIM | Digital control input | Logic-enable and PWM-dimming interface; no internal pullup; must be driven |
| BOOST | Bootstrap gate drive | Supplies NMOS gate voltage; requires external 0.1-µF capacitor to SW |
| SW | Power switch node | Connects to inductor, catch diode anode, and BOOST capacitor; swings below GND during off-time |
| FB | Current-sense feedback | Connected to LED string cathode; regulates current by holding at 0.205 V |
| GND | Signal & power ground | Common return for FB resistor, input cap, and thermal pad; must be low-impedance |
Key Features
| Feature | Design Value |
|---|---|
| Internally compensated current-mode control | Eliminates external compensation network; ensures stable regulation across input/output/temperature variations |
| 1.6-MHz fixed-frequency operation | Reduces EMI filtering requirements and enables miniaturized passive component selection |
| 0.205-V precision feedback reference | Enables accurate LED current setting with standard 1% resistors; reduces heat generation vs higher-voltage references |
| Cycle-by-cycle current limiting | Protects internal switch against short-circuit or overload transients with 2-A (typ) trip threshold |
| Thermal shutdown (165°C) | Prevents permanent damage during sustained overload or poor heatsinking; auto-recovery at ~150°C |
Applications
| Industrial Lighting | LED Flashlights |
|---|---|
Use Scenario: High-bay LED luminaires powered from 12–24 VDC industrial bus with strict thermal and size constraints. IC Role / Device Role / Timing Role: Constant-current buck regulator controlling 5-series HB LED string at 1 A; provides PWM dimming via factory MCU. Use Value: Delivers >85% efficiency at 12 V input with minimal board area due to 1.6-MHz switching and SOT-6 footprint. | Use Scenario: Rechargeable handheld flashlight requiring instant-on, low-quiescent shutdown, and smooth brightness control. IC Role / Device Role / Timing Role: Primary LED driver with EN/DIM pin accepting 1-kHz PWM from tactile switch controller. Use Value: 0.3 µA shutdown current extends battery life; 100-µs startup delay ensures flicker-free illumination. |
| LED Lightbulbs | Automotive Interior Lighting |
Use Scenario: Retrofit A19 LED bulb operating from rectified AC line (12–20 V DC bus) with EMI-sensitive environment. IC Role / Device Role / Timing Role: Buck LED driver with fixed 1.6-MHz frequency to simplify EMI filter design and avoid AM band interference. Use Value: Enables use of low-profile 1.5-µH inductors and avoids audible noise from lower-frequency converters. | Use Scenario: Map light or footwell illumination in 12-V vehicle systems requiring load dump immunity and thermal resilience. IC Role / Device Role / Timing Role: Constant-current source driving 3–4 white LEDs; UVLO (2.74 V) prevents erratic behavior during cranking. Use Value: 440-mV UVLO hysteresis eliminates restart oscillation during engine start transient events. |
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 |
|---|---|---|---|
| LM3405AMK/NOPB | SOT-6 package with identical electrical specs; differs only in tape-and-reel packaging (XMK = cut tape, MK = reel) | No functional difference; same thermal, electrical, and layout behavior | Select LM3405AMK/NOPB for automated SMT assembly; LM3405AXMK/NOPB for prototyping or low-volume hand-soldering |
| TPS61061DRVR | Boost topology, 40-V output capability, 0.5-A max output; lacks internal compensation and 1.6-MHz fixed frequency | Better suited for single-LED or low-VF strings from 2.7–5.5 V sources; not drop-in for 5-LED series strings at 1 A | Choose TPS61061DRVR only when input voltage is below LED string Vf and board space allows larger inductor |
Compared with LM3405AMK/NOPB, LM3405AXMK/NOPB offers identical performance in cut-tape form for flexibility in evaluation and small-batch builds; versus TPS61061DRVR, it provides higher output current, fixed-frequency buck operation, and integrated compensation - making it superior for multi-LED industrial and portable lighting where input exceeds total LED forward voltage.
Availability
LM3405AXMK/NOPB is available at Aetrix Electronics and suitable for industrial lighting, LED flashlights, and automotive interior lighting requiring stable component supply, long-term manufacturability, and TI-qualified reliability data.
Supply support for LM3405AXMK/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 leader delivering analog, embedded processing, and connectivity solutions with emphasis on power management and signal chain innovation.
The LM3405A product line delivers highly integrated, thermally robust LED drivers targeting space-constrained, high-efficiency lighting applications - specifically engineered for simplicity, low external component count, and reliable operation across harsh environments.
FAQ
What is the maximum LED string voltage supported by LM3405AXMK/NOPB?
The LM3405AXMK/NOPB supports LED strings up to approximately 18.5 V (5 × 3.7 V), constrained by its 22-V maximum input voltage and required headroom for the internal switch and catch diode. With VIN = 22 V, VOUT = VIN − VSW − VD1 ≈ 22 V − 0.3 V − 0.7 V = 21 V theoretical, but practical limit is set by minimum duty cycle and thermal derating in SOT-6 package. For 1-A operation, recommended max VOUT is 18.5 V.
Can LM3405AXMK/NOPB operate with input voltage below 3 V?
No. LM3405AXMK/NOPB has a guaranteed operating range of 3 V to 22 V per datasheet Section 6.3. Below 3 V, undervoltage lockout activates (UVLO rising threshold = 2.74 V typ), disabling switching. Operation below 3 V is not characterized or supported; attempting it risks unstable regulation or failure to start.
How does the EN/DIM pin function in LM3405AXMK/NOPB PWM dimming mode?
In LM3405AXMK/NOPB, the EN/DIM pin serves dual purpose: logic-level enable (≥1.8 V) and PWM dimming input. When toggled with 100 Hz–5 kHz square wave, it rapidly enables/disables the entire regulator - producing average LED current proportional to duty cycle. Startup delay (~100 µs) limits minimum pulse width; no external circuitry is needed beyond a clean digital signal source.
What is the thermal resistance (RθJA) of LM3405AXMK/NOPB in its SOT-6 package?
The LM3405AXMK/NOPB in SOT-6 (DDC) package has a junction-to-ambient thermal resistance (RθJA) of 182.9°C/W, as specified in Section 6.4 of the datasheet. This value assumes JEDEC-standard 2-layer board with 1-in² copper; actual performance improves significantly with enhanced PCB copper area under the thermal pad and proper GND stitching.
Is LM3405AXMK/NOPB pin-compatible with other members of the LM3405 family?
Yes - LM3405AXMK/NOPB shares identical pinout and functionality with LM3405AMK/NOPB (reel version) and LM3405ADGNR (MSOP-PowerPAD™). However, the SOT-6 and MSOP packages have different thermal and current capabilities: SOT-6 supports up to 400 mA continuous, while MSOP supports full 1 A. Layout must match chosen package's footprint and thermal requirements.
LM3405AXMK/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
LM3405AXMK/NOPB FAQ
1.How can I place an order for LM3405AXMK/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3405AXMK/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 LM3405AXMK/NOPB reliable?
The price and inventory of LM3405AXMK/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3405AXMK/NOPB is usually 5 days.
3.What payment methods are accepted for LM3405AXMK/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3405AXMK/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3405AXMK/NOPB?
LM3405AXMK/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3405AXMK/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 LM3405AXMK/NOPB?
For technical support, including LM3405AXMK/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3405AXMK/NOPB requirements.
6.How does Aetrix verify that LM3405AXMK/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3405AXMK/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 LM3405AXMK/NOPB meets industry standards.
7.What is the process for return or replacement of LM3405AXMK/NOPB?
All LM3405AXMK/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3405AXMK/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 LM3405AXMK/NOPB part is unused and in its original packaging.
Return procedure for LM3405AXMK/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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