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Texas Instruments LM3431AMH/NOPB
- Part No.:
- LM3431AMH/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 28-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3431AMH/NOPB.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,432
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Product details
Overview
LM3431AMH/NOPB from Texas Instruments is a 3-channel constant-current LED driver IC with integrated boost controller, designed for space-constrained backlight applications. It delivers ±3 mV channel-to-channel current-sense offset mismatch, supports 5 V to 36 V input, regulates LED cathode voltage via CFB feedback, and enables analog/PWM dimming up to 25 kHz in automotive infotainment displays.
For engineers reviewing the LM3431AMH/NOPB datasheet, LM3431AMH/NOPB pinout, LM3431AMH/NOPB application, or LM3431AMH/NOPB equivalent, key selection considerations include its TSSOP-28 exposed-pad package, integrated boost gate drive (LG), three independent NDRVx outputs for external NPN/MOSFET current regulators, and cathode feedback architecture minimizing headroom loss.
Technical Context
The LM3431AMH/NOPB integrates a current-mode PWM boost controller and three high-accuracy linear current regulators in a single die. Its boost stage drives an external NFET with programmable switching frequency (200 kHz–1 MHz) and cycle-by-cycle current limiting, while each channel uses matched SNSx amplifiers with ≤3 mV offset (–40°C to +125°C) to regulate LED string current via external transistors.
LED cathode voltage is regulated at the CFB pin (1.71 V typical, ±2.6 mV/°C tempco) during LED-on periods, while AFB senses output voltage during LED-off intervals and stores it on SS/SH for stable dimming transitions. Fault protection includes LED short/open detection via SC pin, thermal shutdown at 160°C, and programmable fault delay via DLY capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5 V to 36 V - supports wide-range automotive and industrial supplies without external pre-regulation. |
| LED Current Accuracy | ±3 mV max channel-to-channel offset mismatch - ensures uniform brightness across 3 LED strings under full temperature range. |
| Dimming Frequency | Up to 25 kHz - enables flicker-free analog and digital PWM dimming with >100:1 contrast ratio. |
| Boost Switching Frequency | 200 kHz to 1 MHz - adjustable via RT resistor; higher frequencies allow smaller magnetics and reduced EMI filtering. |
| Thermal Shutdown Threshold | 160°C - protects IC and external power devices during overload or poor heatsinking conditions. |
| Cathode Feedback Voltage | 1.71 V ±0.11 V - sets precise LED cathode regulation point, minimizing power dissipation in external current regulators. |
| Operating Junction Temp | –40°C to +125°C - qualified for automotive Grade 1 environments per AEC-Q100. |
Pinout & Package
TSSOP-28 with exposed thermal pad (Package Number PWP0028A); pad must be connected to SGND for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main power input | Accepts 5–36 V supply; powers internal circuitry and boost switch driver. |
| LG | Boost gate driver output | Drives external NFET gate with 0.35 A source / 0.7 A sink capability; RON = 6.4 Ω (source), 2.2 Ω (sink). |
| CFB | Cathode feedback input | Regulates LED cathode voltage to 1.71 V during LED-on time; connects via diode to bottom of each LED string. |
| NDRV1–NDRV3 | Channel current regulator drivers | Drive bases/gates of external NPN transistors or MOSFETs; each supports ≥4 mA sink and ≥10 mA source. |
| SNS1–SNS3 | Current sense inputs | Monitor top-side voltage across channel current-sense resistors; matched offset ≤3 mV ensures inter-channel current matching. |
| DIM | Brightness control input | Accepts analog voltage (0–5 V) or digital PWM signal; controls duty cycle of all 3 channels simultaneously. |
| EN | Enable / UVLO input | Shuts down device below 0.75 V; enables soft-start above 1.23 V; UVLO threshold programmable via resistor divider. |
| THM | LED thermal monitor | Enters standby when pulled below 1.23 V; interfaces directly with NTC thermistor for LED array overtemperature protection. |
Key Features
| Feature | Design Value |
|---|---|
| No audible noise during dimming | Maintains constant output voltage regulation across PWM on/off cycles-eliminates coil whine and capacitor squeal. |
| Integrated boost + linear regulation | Reduces BOM count by combining step-up converter and 3-channel current controllers in one TSSOP-28 package. |
| LED short/open fault detection | SC pin monitors cathode nodes; triggers shutdown or automatic restart based on DLY capacitor setting. |
| Programmable fault delay | DLY pin accepts capacitor to set blanking time before fault response-prevents false trips during transient events. |
| High-accuracy current matching | ≤3 mV max channel-to-channel SNS amplifier offset ensures <±1% current mismatch across full temperature range. |
Applications
| Automotive Infotainment Displays | Small to Medium Format Displays |
|---|---|
Use Scenario: Backlighting for TFT-LCD instrument clusters and center-stack touchscreens in vehicles operating from 9–16 V battery rails. IC Role / Device Role / Timing Role: LM3431AMH/NOPB acts as primary LED current controller and boost regulator, driving three independent RGB or white LED strings with synchronized dimming. Use Value: AEC-Q100 Grade 1 qualification and –40°C to +125°C operation ensure reliability in under-hood and dashboard environments. | Use Scenario: Backlight for portable medical monitors, industrial HMIs, and retail kiosks requiring uniform brightness and low EMI. IC Role / Device Role / Timing Role: LM3431AMH/NOPB provides cathode-regulated current control and adaptive boost voltage scaling to maintain efficiency across varying LED forward voltages. Use Value: CFB-based regulation minimizes headroom loss, reducing power dissipation in external NPN transistors by up to 30% vs. anode-referenced designs. |
| LED Backlight for Space-Constrained Panels | High-Contrast Dimming Systems |
Use Scenario: Slim-profile LCD backlights where PCB area is limited and thermal management is challenging. IC Role / Device Role / Timing Role: LM3431AMH/NOPB integrates boost controller and three current regulators into a single 4.4 mm × 9.7 mm TSSOP-28 EP package. Use Value: Exposed pad improves thermal resistance (θJA = 32°C/W), enabling 3.1 W power dissipation without external heatsink. | Use Scenario: Applications demanding >100:1 contrast ratio such as avionics displays and premium consumer panels. IC Role / Device Role / Timing Role: LM3431AMH/NOPB supports 25 kHz PWM dimming with fixed-frequency operation and minimal delay (<100 ns DIM-to-NDRV edge timing). Use Value: Constant-voltage regulation during dimming eliminates brightness variation and preserves contrast fidelity across duty cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-channel LED driver with integrated boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3431MH/NOPB | Standard version with ±5 mV channel offset (vs. ±3 mV for LM3431AMH/NOPB); identical pinout and feature set. | Lower accuracy requirement; cost-sensitive non-automotive designs where <±1% inter-string current matching is not critical. | Select LM3431MH/NOPB only if full AEC-Q100 Grade 1 qualification and tighter offset spec are unnecessary. |
| TPS61165DRVR | Single-channel boost LED driver with integrated FET; no external transistor support or multi-string current matching capability. | Low-channel-count applications; no need for independent current regulation per string or thermal monitoring. | Choose TPS61165DRVR only for single-string, lower-power (<150 mA) backlight systems without thermal or fault-detection requirements. |
Compared with LM3431MH/NOPB, the LM3431AMH/NOPB offers superior current matching for high-fidelity displays; compared with TPS61165DRVR, it provides true 3-channel independent regulation, external transistor flexibility, and automotive-grade reliability-making it the only option for multi-string, thermally monitored, AEC-Q100-compliant designs.
Availability
LM3431AMH/NOPB is available at Aetrix Electronics and suitable for automotive infotainment displays, small-to-medium format industrial HMIs, and space-constrained LED backlighting applications requiring stable component supply and long-term lifecycle support.
Supply support for LM3431AMH/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 and embedded processing technologies, with leadership in power management, signal chain, and automotive electronics.
The LM3431 product line was developed specifically for high-accuracy, multi-string LED backlight control in automotive and industrial displays-emphasizing thermal robustness, fault resilience, and minimal board footprint.
FAQ
What is the maximum LED string current supported by the LM3431AMH/NOPB?
The LM3431AMH/NOPB does not limit current internally-it relies on external current-sense resistors and NPN/MOSFETs. Each channel supports >200 mA LED string current when paired with appropriately rated external components and proper thermal design. The SNSx amplifier's 2 MHz bandwidth and low offset enable stable regulation at these levels across temperature.
How does the LM3431AMH/NOPB prevent audible noise during PWM dimming?
The LM3431AMH/NOPB maintains constant output voltage regulation during both LED-on and LED-off phases of PWM dimming by using the SS/SH pin to store the AFB reference during off-time. This eliminates switching frequency modulation and inductor current discontinuity-key causes of coil whine-ensuring silent operation even at 25 kHz dimming frequency.
Can the LM3431AMH/NOPB drive both NPN transistors and MOSFETs for LED current regulation?
Yes, the LM3431AMH/NOPB's NDRV1–NDRV3 outputs are designed to drive either NPN transistor bases or NMOS gate terminals. Each NDRV pin provides ≥10 mA source and ≥4 mA sink current with rail-to-rail swing, supporting direct connection to small-signal NPNs or logic-level MOSFETs without additional level-shifting circuitry.
What is the role of the THM pin on the LM3431AMH/NOPB?
The THM pin on the LM3431AMH/NOPB is a dedicated LED thermal monitor input that enters standby mode when pulled below 1.23 V. It interfaces directly with an NTC thermistor placed near the LED array, allowing the LM3431AMH/NOPB to reduce or halt LED current before thermal damage occurs-providing system-level thermal protection beyond IC junction limits.
Does the LM3431AMH/NOPB require external compensation components?
Yes, the LM3431AMH/NOPB requires external compensation on the COMP pin to stabilize both the boost controller and current regulation loops. A standard Type II network (resistor + capacitor + optional series RC) is used, with values selected based on output capacitance, inductance, and desired phase margin-details are provided in TI's SNVS547G datasheet Section 9.2.2.
LM3431AMH/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 28-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 3
- Voltage - Supply (Min):
- 4.5V
- Voltage - Supply (Max):
- 36V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 1MHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-HTSSOP
LM3431AMH/NOPB FAQ
1.How can I place an order for LM3431AMH/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3431AMH/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 LM3431AMH/NOPB reliable?
The price and inventory of LM3431AMH/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3431AMH/NOPB is usually 5 days.
3.What payment methods are accepted for LM3431AMH/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3431AMH/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3431AMH/NOPB?
LM3431AMH/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3431AMH/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 LM3431AMH/NOPB?
For technical support, including LM3431AMH/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3431AMH/NOPB requirements.
6.How does Aetrix verify that LM3431AMH/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3431AMH/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 LM3431AMH/NOPB meets industry standards.
7.What is the process for return or replacement of LM3431AMH/NOPB?
All LM3431AMH/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3431AMH/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 LM3431AMH/NOPB part is unused and in its original packaging.
Return procedure for LM3431AMH/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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