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Texas Instruments LM3431AMHX/NOPB
- Part No.:
- LM3431AMHX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 28-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3431AMHX/NOPB.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,730
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Product details
Overview
LM3431AMHX/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 (–40°C to +125°C), supports 5 V to 36 V input, enables analog/PWM dimming up to 25 kHz, and drives external NPN transistors or MOSFETs for LED strings exceeding 200 mA per channel in automotive infotainment displays.
For engineers reviewing the LM3431AMHX/NOPB datasheet, LM3431AMHX/NOPB pinout, LM3431AMHX/NOPB application, or LM3431AMHX/NOPB equivalent, key selection criteria include cathode feedback (CFB) regulation, thermal shutdown at 160°C, programmable fault delay via DLY capacitor, LED short/open protection, and TSSOP-28 exposed-pad package compatibility with high-density PCB layouts.
Technical Context
The LM3431AMHX/NOPB integrates a current-mode PWM boost controller and three independent linear current regulators. The boost stage uses LG gate drive (0.35 A source / 0.70 A sink), CS current sensing, and AFB/CFB dual-feedback architecture to regulate LED cathode voltage during on-time and anode voltage during off-time.
Each channel features dedicated SNSx/NDRVx pins with ±3 mV max offset mismatch (LM3431A grade), 2 MHz SNS amplifier bandwidth, and NDRV output capable of 3.7 V drive voltage at 5 mA load - enabling precise current control across temperature and process variation in multi-string LED arrays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 36 V - supports wide automotive battery range including cold-crank (4.5 V) and load-dump (36 V) conditions. |
| LED Current Accuracy | ±3 mV channel-to-channel offset mismatch (–40°C to +125°C) - ensures uniform brightness across 3 LED strings without external calibration. |
| Dimming Support | Analog or digital PWM dimming up to 25 kHz with >100:1 contrast ratio - eliminates visible flicker and audible noise in display backlighting. |
| Boost Switching Frequency | Adjustable 200 kHz to 1 MHz via RT resistor - balances EMI, efficiency, and inductor size for compact designs. |
| Thermal Protection | Integrated thermal shutdown at 160°C - prevents device damage during sustained overloads or poor heatsinking. |
| Package | TSSOP-28 with exposed pad - provides low θJA = 32°C/W for power dissipation up to 3.1 W in standard 4-layer PCBs. |
| LED Fault Detection | SC pin monitors LED short (6.0 V threshold) and open (3.5 V clamp) - triggers programmable fault delay before shutdown or automatic restart. |
Pinout & Package
TSSOP-28 exposed pad package (Package Number PWP0028A); exposed pad must be connected to SGND for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power supply input | Primary input rail (4.5–36 V); supplies boost controller and internal bias circuits. |
| PGND | Power ground | High-current return path for boost switch and LED string currents; separate from SGND. |
| VCC | Internal reference output | 5 V ±2.4% regulated supply; requires ≥4.7 µF bypass capacitor to PGND. |
| LG | Boost gate driver | Drives external NFET switch with 0.35 A source / 0.70 A sink capability and 6.4 Ω on-resistance. |
| CS | Boost current sense | Monitors top-side boost sense resistor voltage to control switching and cycle-by-cycle current limit. |
| SNS1–SNS3 | Channel current feedback | Inputs to precision current-sense amplifiers; each referenced to REFIN for programmable LED current. |
| NDRV1–NDRV3 | Channel regulator drive | Outputs drive external NPN bases or NFET gates; 3.7 V drive voltage supports saturated transistor operation. |
| CFB | Cathode feedback | Regulates LED cathode voltage to 1.71 V (typ.) during LED-on time for minimal headroom and optimal efficiency. |
| AFB | Anode feedback | Regulates output anode voltage during LED-off time (startup/dimming); sets OVP threshold via resistor divider. |
| DIM | Brightness control | Accepts analog voltage (0–5 V) or digital PWM signal; 0.4 µs minimum pulse width with 100 ns NDRV response delay. |
Key Features
| Feature | Design Value |
|---|---|
| 3-channel linear current regulation | Independent SNS/NDRV pairs per channel with ±3 mV max offset mismatch over full temperature range - enables uniform luminance in multi-string LCD backlights. |
| Integrated boost controller | Current-mode PWM with adjustable frequency (200 kHz–1 MHz), soft-start (SS/SH), and dual-feedback (CFB/AFB) - eliminates need for external DC/DC controller in space-limited designs. |
| LED short/open protection | SC pin detects faults via diode-connected cathodes; triggers programmable delay (DLY capacitor) before shutdown or auto-restart - improves system reliability in automotive environments. |
| No audible noise during dimming | Constant output voltage regulation maintained across PWM dimming cycles - avoids coil whine and capacitor squeal common in switched LED drivers. |
| Thermal and LED over-temperature monitoring | THM pin accepts thermistor voltage; device enters standby when THM < 1.23 V - protects LED array from thermal runaway in sealed enclosures. |
Applications
| Automotive Infotainment Displays | Small to Medium Format Displays |
|---|---|
Use Scenario: Driving RGB LED backlight for 7–10 inch TFT-LCD dashboards in vehicles operating from –40°C to +125°C ambient. IC Role / Device Role / Timing Role: LM3431AMHX/NOPB acts as primary LED current controller and boost regulator, synchronizing cathode voltage regulation (CFB) with PWM dimming signals to maintain color fidelity. Use Value: ±3 mV channel mismatch and AEC-Q100 Grade 1 qualification ensure consistent brightness and long-term reliability under thermal cycling and vibration stress. | Use Scenario: Powering white LED arrays in industrial HMI panels requiring >100:1 dimming contrast without audible noise. IC Role / Device Role / Timing Role: LM3431AMHX/NOPB serves as integrated LED driver with analog dimming input and soft-start (SS/SH) to prevent inrush current during power-up sequences. Use Value: Integrated CFB/AFB feedback eliminates need for external op-amps or voltage references, reducing BOM count by 4+ components per channel. |
| LED Backlight for Space-Constrained Devices | Multi-String Architectures Requiring Expandability |
Use Scenario: Backlighting compact medical display modules where board area is limited to < 2 cm² for driver circuitry. IC Role / Device Role / Timing Role: LM3431AMHX/NOPB functions as single-chip solution combining boost conversion and 3-channel current regulation - replacing discrete controller + 3 op-amp + 3 transistor designs. Use Value: TSSOP-28 exposed pad package achieves 3.1 W power dissipation in minimal footprint, enabling direct mounting to metal chassis for passive cooling. | Use Scenario: Scalable LED lighting systems where initial design uses 3 strings but future revisions require 6 strings. IC Role / Device Role / Timing Role: LM3431AMHX/NOPB provides daisy-chainable architecture; two devices can synchronize DIM and MODE/F pins to coordinate 6-channel operation. Use Value: Shared RT and FF pins allow matched switching frequencies and synchronized dimming edges - critical for flicker-free video playback in broadcast monitors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-channel LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3431MHX/NOPB | Standard-grade version with ±5 mV channel offset (vs. ±3 mV for LM3431A); same pinout and feature set. | Not qualified to AEC-Q100 Grade 1; suitable for commercial/industrial displays but not automotive. | Select LM3431MHX/NOPB only if AEC-Q100 qualification and tighter offset tolerance are not required. |
| TPS61165DRVR | Single-channel boost LED driver with integrated FET; no multi-channel current regulation or CFB feedback. | Lacks 3-channel independent control and thermal monitoring; requires external transistors for multi-string expansion. | Choose TPS61165DRVR only for cost-sensitive single-string applications where board area is less constrained than performance. |
Compared with LM3431MHX/NOPB, the LM3431AMHX/NOPB offers tighter current matching for automotive-grade luminance uniformity; compared with TPS61165DRVR, it provides integrated multi-channel regulation and cathode feedback - eliminating 9+ external components in 3-string designs.
Availability
LM3431AMHX/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 across extended temperature ranges and long production lifecycles.
Supply support for LM3431AMHX/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 backlighting in automotive and industrial displays - integrating boost conversion and linear current regulation to minimize board area and improve thermal performance.
FAQ
What is the maximum LED string current supported by the LM3431AMHX/NOPB?
The LM3431AMHX/NOPB supports LED string currents exceeding 200 mA per channel using external NPN transistors or MOSFETs. Its NDRV outputs deliver 3.7 V drive voltage at 5 mA load, and SNS amplifiers maintain ±3 mV offset mismatch across –40°C to +125°C - enabling stable high-current regulation without external gain compensation. Actual maximum current depends on external transistor selection and thermal design.
How does the LM3431AMHX/NOPB prevent audible noise during PWM dimming?
The LM3431AMHX/NOPB maintains constant output voltage regulation during PWM dimming by using dual-feedback architecture: CFB regulates LED cathode voltage during on-time, while AFB holds output anode voltage stable during off-time via sample-hold (SS/SH). This eliminates inductor and capacitor vibration caused by varying duty-cycle ripple - a key differentiator from basic boost drivers that modulate output voltage directly.
What is the purpose of the THM pin on the LM3431AMHX/NOPB?
The THM pin on the LM3431AMHX/NOPB monitors LED array temperature via an external thermistor divider. When THM voltage drops below 1.23 V, the device enters standby mode - reducing LED current and preventing thermal runaway. This function is independent of junction temperature shutdown (160°C), providing proactive thermal management for LED lifetime extension in enclosed displays.
Can the LM3431AMHX/NOPB drive more than three LED strings?
Yes, the LM3431AMHX/NOPB can be expanded to drive up to six LED strings by cascading two devices. Synchronization is achieved by connecting DIM, MODE/F, and RT pins between ICs, ensuring matched dimming timing and switching frequency. Each LM3431AMHX/NOPB retains independent current programming via its own REFIN resistor network, preserving per-string accuracy.
What protection features are integrated into the LM3431AMHX/NOPB?
The LM3431AMHX/NOPB integrates LED short detection (SC pin, 6.0 V threshold), LED open protection (SC clamp at 3.5 V), programmable fault delay (DLY capacitor), cycle-by-cycle current limit (ILIM pin), output overvoltage protection (AFB-based, 2.0 V threshold), and thermal shutdown (160°C). All protections trigger either automatic restart or latched shutdown based on LEDFAULT configuration - configurable for automotive fail-safe requirements.
LM3431AMHX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 28-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- 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
LM3431AMHX/NOPB FAQ
1.How can I place an order for LM3431AMHX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3431AMHX/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 LM3431AMHX/NOPB reliable?
The price and inventory of LM3431AMHX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3431AMHX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3431AMHX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3431AMHX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3431AMHX/NOPB?
LM3431AMHX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3431AMHX/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 LM3431AMHX/NOPB?
For technical support, including LM3431AMHX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3431AMHX/NOPB requirements.
6.How does Aetrix verify that LM3431AMHX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3431AMHX/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 LM3431AMHX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3431AMHX/NOPB?
All LM3431AMHX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3431AMHX/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 LM3431AMHX/NOPB part is unused and in its original packaging.
Return procedure for LM3431AMHX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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