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Texas Instruments LM3405AXMY/NOPB
- Part No.:
- LM3405AXMY/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 8-PowerTSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM3405AXMY/NOPB.pdf
- Description:
- IC LED DRVR RGLTR PWM 1A 8HVSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,604
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Product details
Overview
LM3405AXMY/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 typical RDS(ON), and EN/DIM pin for PWM dimming. It drives up to five high-brightness LEDs in series at 1 A from 3 V to 22 V input, used in compact industrial lighting and LED flashlight designs.
For engineers reviewing the LM3405AXMY/NOPB datasheet, LM3405AXMY/NOPB pinout, LM3405AXMY/NOPB application, or LM3405AXMY/NOPB equivalent, key selection considerations include its fixed 1.6-MHz switching frequency, thermal shutdown (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 LM3405AXMY/NOPB implements current-mode control with internal compensation, enabling stable regulation across wide input (3–22 V) and load (0.2–1 A) ranges without external loop compensation components. Its 1.6-MHz oscillator allows use of sub-2.2-µH inductors and low-ESR ceramic capacitors, minimizing board area.
It integrates a 360-mΩ NMOS power switch, 0.205-V precision feedback reference, and dedicated BOOST/SW pins supporting bootstrap gate drive with 2.5–5.5 V gate-to-source voltage range. Protection includes undervoltage lockout (2.74 V rising, 2.3 V falling), overcurrent detection (328 mV FB threshold), and thermal shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3 V to 22 V - supports 12-V automotive, 5-V USB-powered, and 19-V industrial rails without pre-regulation. |
| Switching Frequency | 1.6 MHz (typ) - enables use of ≤2.2 µH shielded inductors and 10–22 µF ceramic output capacitors. |
| LED Current Accuracy | ±5% over temp - achieved via 0.205 V ±17 mV feedback reference and low bias current (250 nA max). |
| RDS(ON) | 360 mΩ (typ) at VBOOST–VSW = 3 V - limits conduction loss to <360 mW at 1 A, critical for thermal performance in MSOP-PowerPAD™. |
| Shutdown Current | 0.3 µA (typ) at VIN = 5 V - ensures battery-powered flashlights retain >99.9% charge during standby. |
| UVLO Threshold | 2.74 V (rising), 2.3 V (falling) with 440 mV hysteresis - prevents erratic startup during brownout or slow-ramp input conditions. |
| Thermal Shutdown | 165°C (trip), ~150°C (release) - protects MSOP-PowerPAD™ package under sustained 1-A load with limited airflow. |
Pinout & Package
LM3405AXMY/NOPB uses the MSOP-PowerPAD™-8 package (3.00 mm × 3.00 mm), with exposed thermal pad (DAP) soldered to PCB ground plane for enhanced heat dissipation (RθJB = 38.9°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (Pin 4) | Bootstrap gate-drive supply | Connects to bootstrap capacitor; supplies ≥2.5 V above SW to fully enhance internal NMOS switch. |
| GND (Pins 2, 7) | Signal and power ground | Dual ground pins reduce ground bounce; place FB resistor's ground connection nearest Pin 2. |
| FB (Pin 1) | Current-sense feedback input | Sinks 250 nA max; sets LED current via IF = 0.205 V / R1; requires Kelvin connection for accuracy. |
| EN/DIM (Pin 8) | Enable and PWM dimming control | Logic-high (>1.8 V) enables operation; PWM toggling (100 Hz–5 kHz) controls average LED brightness. |
| VIN (Pin 6) | Main input supply | Accepts 3–22 V; requires local 1-µF ceramic bypass capacitor between VIN and GND (Pin 2). |
| SW (Pin 5) | Power switch node | Connects to inductor, catch diode cathode, and bootstrap capacitor; swings from GND to VIN – IF×RDS(ON). |
Key Features
| Feature | Design Value |
|---|---|
| Internally compensated current-mode control | Eliminates need for external compensation network, reducing BOM count and layout sensitivity across 3–22 V input range. |
| 1.6-MHz fixed-frequency operation | Enables use of compact 1.0–2.2 µH shielded inductors and 10–22 µF X5R/X7R ceramic output capacitors. |
| 0.205-V precision feedback reference | Minimizes power loss in current-setting resistor (e.g., 0.2 Ω for 1 A), improving efficiency vs. higher-reference competitors. |
| EN/DIM pin with PWM dimming support | Accepts 100 Hz–5 kHz logic-level PWM signals directly; no external driver needed for brightness control in flashlight or indicator apps. |
| Thermal shutdown with hysteresis | Shuts down at 165°C junction, restarts at ~150°C - prevents thermal runaway in enclosed LED modules with limited heatsinking. |
Applications
| Industrial LED Lighting | Portable LED Flashlights |
|---|---|
|
Use Scenario: High-efficiency, thermally constrained LED luminaires for factory floor or warehouse lighting, operating from 12–24 V DC rails. IC Role / Device Role / Timing Role: Constant-current buck regulator delivering regulated 1-A output to 5-series LED string; manages thermal load via PowerPAD™ and cycle-by-cycle current limiting. Use Value: Enables compact 3×3 mm footprint design with >88% efficiency at 12 VIN/3.7 VLED×5, eliminating need for external thermal management beyond PCB copper pour. |
Use Scenario: Rechargeable AA/18650-powered tactical flashlights requiring instant-on, flicker-free illumination with adjustable brightness. IC Role / Device Role / Timing Role: Primary LED driver with integrated soft-start and EN/DIM-controlled PWM dimming; handles rapid enable/disable transitions without current overshoot. Use Value: Delivers 100:1 dimming ratio (100 Hz–5 kHz) and <100 µs startup delay, enabling responsive user interface while maintaining 0.3 µA shutdown current for multi-week battery shelf life. |
| LED Lightbulb Retrofit Modules | Automotive Interior Lighting |
|
Use Scenario: AC/DC-powered LED retrofit bulbs replacing incandescent lamps, requiring high reliability and EMI-compliant operation. IC Role / Device Role / Timing Role: Constant-current controller driving 3–5 high-brightness LEDs in series; operates at 1.6 MHz to shift switching noise above AM radio band. Use Value: Reduces EMI filter size by avoiding low-frequency (<500 kHz) operation; internal compensation ensures stability with low-ESR ceramic caps, lowering bill-of-materials cost. |
Use Scenario: 12-V automotive cabin lighting (map lights, footwell LEDs) needing robust operation across cold-crank (-40°C) to hot-soak (+125°C) conditions. IC Role / Device Role / Timing Role: LED current regulator with UVLO (2.74 V), thermal shutdown (165°C), and 125°C max junction rating - meets AEC-Q100 stress requirements. Use Value: Sustains 1-A output across full automotive temperature range without derating; 440 mV UVLO hysteresis prevents flicker during engine cranking transients. |
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, 500-kHz switching, SO-8 package, 0.235-V VFB, no internal compensation (requires external RC network). | Better suited for lower-power (<500 mA), cost-sensitive designs where board space is less constrained and loop tuning is acceptable. | Select LM3404MHX/NOPB when thermal budget allows larger SO-8 package and design team has loop compensation expertise. |
| TPS61061DRVR | Boost topology, 40-V output capability, 1.2-MHz switching, 0.5-A max, 0.5-V VFB, integrated Schottky diode. | Required for single-LED or low-VF strings where input voltage is below LED forward voltage (e.g., 3.3-V rail → 3.7-V white LED). | Choose TPS61061DRVR only for boost-based LED strings; not a functional replacement for buck applications like LM3405AXMY/NOPB. |
Compared with LM3405AXMY/NOPB, LM3404MHX/NOPB trades higher board area and design complexity for lower unit cost, while TPS61061DRVR serves fundamentally different topology needs - neither offers pin-compatible or drop-in substitution, and both require schematic and layout revision.
Availability
LM3405AXMY/NOPB is available at Aetrix Electronics and suitable for industrial LED lighting, portable LED flashlights, LED lightbulb retrofit modules, and automotive interior lighting requiring stable component supply and long-term production continuity.
Supply support for LM3405AXMY/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 experience in high-reliability LED driver design.
The LM3405A product line delivers compact, thermally optimized constant-current buck drivers for high-brightness LED applications, emphasizing ease of use through internal compensation and robust protection features.
FAQ
What is the maximum LED string voltage supported by LM3405AXMY/NOPB?
The LM3405AXMY/NOPB supports LED strings up to approximately 18.5 V, calculated as VIN(MAX) − VD1 − IF×RDS(ON) ≈ 22 V − 0.7 V − 0.36 V = 20.94 V, but practical limit is set by minimum duty cycle and thermal constraints. At 12 VIN, it reliably drives 5×3.7-V LEDs (18.5 V total) with margin for diode drop and ripple.
Can LM3405AXMY/NOPB operate from a 3.3-V input to drive a single 3.2-V white LED?
No - LM3405AXMY/NOPB is a buck converter requiring VIN > VLED + VD1 + IF×RDS(ON). With a 3.3-V input, headroom is insufficient to sustain 1-A current through a 3.2-V LED plus diode drop and switch loss. For such cases, a boost driver like TPS61061 is required instead of LM3405AXMY/NOPB.
What is the recommended inductor value for LM3405AXMY/NOPB at 12-V input and 1-A output?
For 12-V input driving a 18.5-V LED string (5×3.7 V), duty cycle D ≈ (VOUT + VD1) / (VIN + VD1 − VSW) ≈ 19.2 / 12.3 ≈ 0.75. Using Equation 17 from the datasheet with r = 0.35, fSW = 1.6 MHz, and IF = 1 A, the recommended inductor is 1.5 µH ±20%, rated for ≥1.5-A saturation current and low core loss at 1.6 MHz.
Does LM3405AXMY/NOPB require an external bootstrap diode?
Yes - LM3405AXMY/NOPB requires an external bootstrap diode (e.g., 1N4148 or BAT54) between VIN and BOOST pins to charge the bootstrap capacitor during SW low-time. The diode must support ≥20-mA peak charge current and have low forward voltage (<0.4 V) to ensure sufficient gate drive voltage (2.5–5.5 V) across BOOST–SW for reliable NMOS switching.
How does the EN/DIM pin function during PWM dimming on LM3405AXMY/NOPB?
On LM3405AXMY/NOPB, the EN/DIM pin accepts logic-level PWM signals (100 Hz–5 kHz) to toggle the internal power switch on/off. Each high pulse initiates a soft-start sequence (~100 µs to full current); low pulses force shutdown with 0.3 µA quiescent current. Dimming ratio is linear with duty cycle below 5 kHz, but degrades above that due to finite startup time.
LM3405AXMY/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
LM3405AXMY/NOPB FAQ
1.How can I place an order for LM3405AXMY/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3405AXMY/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 LM3405AXMY/NOPB reliable?
The price and inventory of LM3405AXMY/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3405AXMY/NOPB is usually 5 days.
3.What payment methods are accepted for LM3405AXMY/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3405AXMY/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3405AXMY/NOPB?
LM3405AXMY/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3405AXMY/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 LM3405AXMY/NOPB?
For technical support, including LM3405AXMY/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3405AXMY/NOPB requirements.
6.How does Aetrix verify that LM3405AXMY/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3405AXMY/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 LM3405AXMY/NOPB meets industry standards.
7.What is the process for return or replacement of LM3405AXMY/NOPB?
All LM3405AXMY/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3405AXMY/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 LM3405AXMY/NOPB part is unused and in its original packaging.
Return procedure for LM3405AXMY/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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