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Texas Instruments LM3405AXMYX/NOPB
- Part No.:
- LM3405AXMYX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 8-PowerTSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM3405AXMYX/NOPB.pdf
- Description:
- IC LED DRVR RGLTR PWM 1A 8HVSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,961
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Product details
Overview
LM3405AXMYX/NOPB from Texas Instruments is a 1.6-MHz, 1-A constant-current buck LED driver IC in MSOP-PowerPAD™-8 package, featuring internal compensation, 0.205-V feedback reference, 360-mΩ NMOS switch, and EN/DIM pin for PWM dimming - designed for high-efficiency series LED strings up to 5× HB-LEDs (e.g., automotive map lights or industrial task lighting).
For engineers reviewing the LM3405AXMYX/NOPB datasheet, LM3405AXMYX/NOPB pinout, LM3405AXMYX/NOPB application, or LM3405AXMYX/NOPB equivalent, key selection criteria include its 3–22-V input range, thermal shutdown at 165°C, cycle-by-cycle current limit (2 A typ), 40-nA shutdown current, and compatibility with ceramic output capacitors and small-surface-mount inductors.
Technical Context
The LM3405AXMYX/NOPB implements current-mode control with fixed 1.6-MHz switching frequency and internal compensation, eliminating external loop compensation components. Its feedback architecture regulates LED current via a 0.205-V reference applied across an external sense resistor (R1), enabling precise current setting independent of LED forward voltage variation.
It integrates a 360-mΩ NMOS power switch (MSOP-PowerPAD™ variant), BOOST pin for gate-drive bootstrapping, and EN/DIM pin supporting both logic enable and 100 Hz–5 kHz PWM dimming. Protection includes undervoltage lockout (2.74 V rising, 2.3 V falling), overcurrent detection (328 mV FB threshold), and thermal shutdown (165°C junction).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3 V to 22 V - supports wide-input industrial and automotive supplies without pre-regulation. |
| LED Current | Up to 1 A - enables full-brightness operation for 5-series high-brightness LEDs (e.g., 3.7 V × 5 ≈ 18.5 V VOUT). |
| fSW | 1.6 MHz (typ) - allows use of compact 1–4.7 µH shielded inductors and low-ESR ceramic capacitors. |
| VFB | 0.205 V (typ) - low-reference voltage minimizes I²R loss in current-sense resistor R1, improving efficiency. |
| RDS(ON) | 360 mΩ (typ, MSOP-PowerPAD™) - reduces conduction loss at 1-A load; thermal resistance RθJA = 55.3°C/W enables high-power density layout. |
| Shutdown IQ | 0.3 µA (typ at VIN = 5 V) - enables ultra-low-power standby in battery-powered flashlights or emergency lighting. |
| UVLO Threshold | 2.74 V (rising), 2.3 V (falling) - 440-mV hysteresis prevents oscillation during brown-out conditions. |
Pinout & Package
LM3405AXMYX/NOPB is packaged in an 8-pin MSOP-PowerPAD™ (DGN) with exposed thermal pad (DAP) soldered to PCB ground for enhanced thermal performance. Package body size is 3.00 mm × 3.00 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (Pin 4) | Bootstrap gate-drive supply | Charged via external diode/capacitor to generate ≥2.5 V above SW for NMOS turn-on; must stay ≤5.5 V above SW. |
| GND (Pins 2, 7) | Signal and power ground | Dual ground pins reduce noise coupling; feedback resistor (R1) must connect to Pin 2 for accurate current sensing. |
| FB (Pin 1) | Current-sense feedback input | Sinks 250 nA max bias current; regulated at 0.205 V to set LED current via R1 = 0.205 V / ILED. |
| EN/DIM (Pin 8) | Enable and PWM dimming control | Logic-high (>1.8 V) enables operation; PWM signal (100 Hz–5 kHz) directly modulates LED on/off for analog-equivalent dimming. |
| VIN (Pin 6) | Main input supply | Accepts 3–22 V; requires local 1-µF ceramic bypass capacitor to GND for stability and EMI reduction. |
| SW (Pin 5) | Switch node | Connects to inductor, catch diode cathode, and bootstrap capacitor; swings from ~0 V to VIN − ILED×RDS(ON) during operation. |
| NC (Pin 3) | No connection | Unbonded pin - must be left floating; no routing or copper fill required. |
| DAP | Thermal pad (exposed bottom) | Must be soldered to solid PCB ground plane for thermal dissipation; contributes to RθJB = 38.9°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Internally compensated current-mode control | Eliminates external compensation network, reducing BOM count and layout sensitivity while maintaining stable regulation across 0.2–1 A LED loads. |
| 1.6-MHz fixed-frequency operation | Enables use of sub-5-mm footprint inductors and 0805/1206 ceramic capacitors, minimizing solution size for space-constrained lighting modules. |
| 0.205-V precision feedback reference | Reduces power loss in current-sense resistor by >60% vs. conventional 1.25-V references, critical for thermally constrained LED drivers. |
| Cycle-by-cycle current limit (2 A typ) | Prevents switch failure during short-circuit or cold-start inrush by limiting peak inductor current per switching cycle. |
| Thermal shutdown (165°C) | Protects device under sustained overload or poor heatsinking; automatic recovery occurs only after junction cools to ~150°C. |
Applications
| Automotive Interior Lighting | Industrial Task Lighting |
|---|---|
|
Use Scenario: Driving 4–5 white LEDs in overhead map lights or door courtesy lamps from 12-V vehicle battery with load-dump immunity. IC Role / Device Role / Timing Role: Constant-current buck regulator providing stable 700–1000 mA output regardless of battery voltage sag (9–16 V) or LED VF drift. Use Value: Eliminates need for external current mirrors or op-amp feedback loops; UVLO prevents flicker during cranking (VIN < 2.74 V). |
Use Scenario: High-reliability LED arrays in factory floor workstations requiring continuous 24/7 operation with minimal thermal derating. IC Role / Device Role / Timing Role: Primary LED current controller with integrated thermal protection and 55.3°C/W junction-to-ambient thermal resistance. Use Value: MSOP-PowerPAD™ package enables direct thermal coupling to metal-core PCB, sustaining 1-A output at 85°C ambient without forced air. |
| Portable LED Flashlights | Smart Home LED Bulbs |
|
Use Scenario: Single-cell Li-ion (3–4.2 V) or 3×AA (4.5 V) powered tactical flashlights requiring instant-on, high-CRI illumination. IC Role / Device Role / Timing Role: Efficient buck converter stepping down battery voltage to drive 3-series LEDs at 1 A with <100 µs soft-start delay. Use Value: 0.3 µA shutdown current extends shelf life; EN/DIM pin accepts microcontroller PWM for programmable brightness levels. |
Use Scenario: Retrofit A19 LED bulbs using AC-DC offline stage followed by constant-current DC-DC stage for precise lumen maintenance. IC Role / Device Role / Timing Role: Secondary-side current regulator ensuring consistent light output across line-voltage variations (±10%) and temperature shifts. Use Value: Internal compensation and 1.6-MHz switching minimize EMI filter requirements, easing EMC certification for Class B lighting products. |
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 |
|---|---|---|---|
| LM3404MHX/NOPB | Lower 1-A max current rating, 500-kHz fSW, SOT-23-6 package, 0.235-V VFB, RDS(ON) = 220 mΩ | Better suited for lower-power (<500 mA), cost-sensitive designs where board space is less constrained and thermal limits are looser. | Select when 500-kHz switching suffices and smaller package footprint is prioritized over 1-A capability. |
| TPS92515HVDDAR | Higher 65-V VIN max, 2-A current capability, integrated MOSFET, 0.1-V VFB, 1.8-MHz fSW, thermal foldback | Targeted at high-input-voltage applications (e.g., 24/48-V industrial rails) requiring higher current or tighter thermal management. | Choose for systems needing >22-V input support or active thermal derating beyond fixed shutdown. |
Compared with LM3405AXMYX/NOPB, LM3404MHX/NOPB trades switching frequency and thermal performance for smaller size and lower cost, while TPS92515HVDDAR extends input voltage and current range at the expense of higher BOM complexity and price - making LM3405AXMYX/NOPB optimal for 3–22-V, 1-A, thermally dense LED lighting modules.
Availability
LM3405AXMYX/NOPB is available at Aetrix Electronics and suitable for automotive interior lighting, industrial task lighting, portable LED flashlights, and smart home LED bulbs requiring stable component supply, long-term manufacturability, and TI-qualified reliability data.
Supply support for LM3405AXMYX/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 specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability LED driver design and automotive-grade qualification.
The LM3405A product line delivers compact, thermally robust constant-current buck drivers for medium-power LED lighting, targeting applications where efficiency, small form factor, and ease of implementation outweigh programmability or ultra-wide VIN range.
FAQ
What is the maximum LED string voltage supported by LM3405AXMYX/NOPB?
The LM3405AXMYX/NOPB supports up to 5 high-brightness white LEDs in series, assuming ~3.7 V forward voltage per LED at 1 A, yielding ~18.5 V VOUT. With 22-V maximum VIN and typical diode drop (~0.5 V), the practical VOUT ceiling remains within safe operating limits. Output voltage is determined by VOUT = (n × VF) + 0.205 V, where n is LED count and VF is per-LED forward voltage.
Can LM3405AXMYX/NOPB operate from a single 3.7-V Li-ion cell?
Yes, LM3405AXMYX/NOPB operates down to 3 V VIN, making it compatible with discharged single-cell Li-ion (≥3.0 V). However, at low VIN, duty cycle approaches 94%, reducing headroom for boost capacitor charging and increasing thermal stress. For reliable 1-A operation across full battery range, pairing with a 3.3-V LDO pre-regulator or using 2-cell configuration is recommended.
How does the EN/DIM pin function in LM3405AXMYX/NOPB?
The EN/DIM pin on LM3405AXMYX/NOPB serves dual roles: applying >1.8 V enables operation, while applying a 100 Hz–5 kHz PWM signal enables analog-equivalent brightness control. Each PWM high pulse initiates a ~100-µs soft-start sequence, so minimum off-time must exceed this delay to avoid current overshoot. No external pull-up is required, but floating is prohibited.
What thermal considerations apply to LM3405AXMYX/NOPB in MSOP-PowerPAD™ package?
LM3405AXMYX/NOPB in MSOP-PowerPAD™ has RθJA = 55.3°C/W and RθJB = 38.9°C/W. To sustain 1-A continuous output at 85°C ambient, the DAP thermal pad must be fully soldered to ≥1-in² copper area tied to system ground. Without proper DAP grounding, junction temperature may exceed 125°C, triggering thermal shutdown. Layout guidelines require short, wide traces to GND and minimized thermal resistance paths.
Is an external bootstrap diode required for LM3405AXMYX/NOPB?
Yes, LM3405AXMYX/NOPB requires an external Schottky diode (e.g., 1N5819) between VIN and BOOST pins to charge the bootstrap capacitor (C3). This diode must support ≥20 mA peak current and have low forward voltage (<0.4 V) to ensure sufficient gate-drive voltage (2.5–5.5 V above SW) across the full input range. Omitting or misplacing this diode causes erratic switching or complete failure to start.
LM3405AXMYX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-PowerTSSOP, 8-MSOP (0.118", 3.00mm Width)
- 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:
- 8-HVSSOP
LM3405AXMYX/NOPB FAQ
1.How can I place an order for LM3405AXMYX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3405AXMYX/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 LM3405AXMYX/NOPB reliable?
The price and inventory of LM3405AXMYX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3405AXMYX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3405AXMYX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3405AXMYX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3405AXMYX/NOPB?
LM3405AXMYX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3405AXMYX/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 LM3405AXMYX/NOPB?
For technical support, including LM3405AXMYX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3405AXMYX/NOPB requirements.
6.How does Aetrix verify that LM3405AXMYX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3405AXMYX/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 LM3405AXMYX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3405AXMYX/NOPB?
All LM3405AXMYX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3405AXMYX/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 LM3405AXMYX/NOPB part is unused and in its original packaging.
Return procedure for LM3405AXMYX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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