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Texas Instruments LM3431QMHX/NOPB
- Part No.:
- LM3431QMHX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 28-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3431QMHX/NOPB.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,750
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Product details
Overview
LM3431QMHX/NOPB from Texas Instruments is an automotive-grade 3-channel constant-current LED driver with integrated boost controller, delivering ±5 mV SNS amplifier offset voltage, 651–749 kHz adjustable switching frequency, and 5 V to 36 V input range for backlighting automotive infotainment displays. It drives external NPN transistors or MOSFETs with NDRVx source/sink capability up to 20 mA/8 mA and supports analog/PWM dimming up to 25 kHz.
For engineers reviewing the LM3431QMHX/NOPB datasheet, LM3431QMHX/NOPB pinout, LM3431QMHX/NOPB application, or LM3431QMHX/NOPB equivalent, key selection criteria include channel-to-channel current mismatch (≤6 mV), cathode feedback (CFB) regulation at 1.71 V, thermal shutdown at 160°C, LED short/open protection via SC pin, and AEC-Q100 Grade 1 qualification (−40°C to +125°C).
Technical Context
The LM3431QMHX/NOPB integrates a current-mode PWM boost controller and three independent linear current regulators in a single TSSOP-28 exposed-pad package. Its CFB pin regulates LED cathode voltage during on-time while AFB pin controls output voltage during off-time using sample-hold logic, enabling stable dimming without audible noise.
It implements cycle-by-cycle current limiting via ILIM pin, programmable fault delay through DLY capacitor, and dual-mode dimming control (analog voltage or digital PWM) with MODE/F pin selection. The device uses internal reference (2.5 V ±50 mV) and REFIN-based current setting with ≤30 µA SNSx bias current across −40°C to +125°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5 V to 36 V - supports wide automotive battery rail including cold-crank (4.5 V min) and load-dump transients. |
| LED Current Accuracy | ±5 mV SNSx offset (LM3431), ≤6 mV channel-to-channel mismatch - enables <1% current error across 3 strings at 200 mA each. |
| Switching Frequency | 651–749 kHz (RRT = 34.8 kΩ) - adjustable up to 1 MHz; minimum 180 kHz ensures EMI compliance and low output ripple. |
| Dimming Support | Analog or digital PWM up to 25 kHz - achieves >100:1 contrast ratio; no audible noise due to constant cathode voltage regulation. |
| Thermal Protection | 160°C junction shutdown with hysteresis - safeguards IC and LED array under sustained overtemperature conditions. |
| AEC-Q100 Grade | Grade 1 (−40°C to +125°C TJ) - qualified for automotive infotainment display systems requiring long-term reliability. |
| Package | TSSOP-28 with exposed pad - 32°C/W θJA enables 3.1 W power dissipation at 25°C ambient for high-current LED drive. |
Pinout & Package
TSSOP-28 exposed pad (Package Number PWP0028A); exposed pad must be connected to SGND for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Main power input | Accepts 5–36 V supply; feeds boost controller and internal LDO for VCC generation. |
| PGND (2) | Power ground return | Low-impedance path for boost switch current and sense resistor return; separate from SGND. |
| VCC (3) | Internal reference output | 5 V ±240 mV regulated output; requires ≥4.7 µF bypass capacitor to PGND for stability. |
| LG (4) | Boost gate driver | Drives external NFET gate; 0.35 A source / 0.7 A sink capability with 6.4 Ω/2.2 Ω on-resistance. |
| CS (5) | Boost current sense | Monitors top-side of boost sense resistor; used for PWM control and cycle-by-cycle current limit. |
| ILIM (6) | Current limit threshold adjust | Sets peak inductor current limit via resistor to CS; prevents overcurrent during startup or fault. |
| MODE/F (7) | Dimming mode select | Pull high for digital PWM; connect capacitor to GND to set internal analog dimming frequency. |
| CFB (17) | Cathode feedback | Regulates LED cathode voltage at 1.71 V during LED-on time; minimizes headroom and improves efficiency. |
| SC (18) | LED short-circuit detection | Monitors cathode nodes via diodes; triggers fault if voltage exceeds 6.0 V (short) or falls below 3.5 V (open). |
| DIM (27) | Brightness control input | Accepts 0–5 V analog or 0–5 V PWM signal; 0.4 µs minimum pulse width with 100 ns NDRV delay. |
| EN (28) | Enable/UVLO control | Shuts down IC below 0.75 V; enables soft-start above 1.23 V; UVLO threshold programmable via resistor divider. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost + 3-channel linear regulation | Eliminates need for external boost IC and discrete current sinks; reduces BOM count and PCB area in space-constrained displays. |
| Cathode feedback (CFB) architecture | Maintains constant 1.71 V at LED cathode during dimming - avoids output voltage modulation and audible coil whine. |
| Programmable fault response | DLY pin sets shutdown delay (capacitor-timed); LEDOFF pin enables automatic restart or external driver control during fault. |
| Channel-matched current regulation | ≤6 mV max channel-to-channel SNSx offset ensures uniform brightness across 3 LED strings without per-channel trimming. |
| LED open/short protection | SC pin detects both failure modes; AFB-based OVP (2.0 V threshold) protects against overvoltage during open-string events. |
Applications
| Automotive Infotainment Displays | Small to Medium Format Displays |
|---|---|
Use Scenario: Backlighting TFT-LCD clusters in instrument panels and center-stack infotainment units operating across automotive temperature range. IC Role / Device Role / Timing Role: 3-channel constant-current driver with integrated boost, regulating cathode voltage via CFB pin during PWM dimming cycles. Use Value: AEC-Q100 Grade 1 qualification and 160°C thermal shutdown ensure reliability in under-hood and dashboard environments. | Use Scenario: Driving RGB LED backlights in portable medical monitors and industrial HMIs where color uniformity and EMI control are critical. IC Role / Device Role / Timing Role: Linear current regulator controlling three independent LED strings with <6 mV channel mismatch and 25 kHz dimming support. Use Value: Analog/digital dimming flexibility and no-audible-noise operation enable silent, flicker-free brightness control in noise-sensitive settings. |
| Automotive HUD Systems | Avionics Display Backlights |
Use Scenario: High-brightness LED backlight for head-up displays requiring precise luminance control and fast transient response. IC Role / Device Role / Timing Role: Boost controller maintains stable output voltage while NDRVx drivers modulate current through external NPNs/MOSFETs. Use Value: 651–749 kHz switching frequency and 170 ns minimum on-time support compact magnetics and rapid dimming transitions. | Use Scenario: Redundant LED backlighting in certified avionics displays needing fault detection, thermal monitoring, and latch-off behavior. IC Role / Device Role / Timing Role: Fault management hub using SC, THM, and DLY pins to detect LED short/open, overtemperature, and set shutdown delay. Use Value: Programmable fault delay and LEDOFF-controlled external driver sequencing meet DO-160 and RTCA/DO-254 safety requirements. |
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 |
|---|---|---|---|
| LM3431AMHX/NOPB | Reduced SNSx offset (±3 mV vs. ±5 mV); same pinout, package, and feature set. | Higher accuracy required for premium automotive displays with tighter brightness uniformity specs. | Select LM3431AMHX/NOPB when channel matching better than 5 mV is mandatory; otherwise LM3431QMHX/NOPB suffices. |
| TPS61165DRVR | Single-channel boost LED driver with I²C interface; no integrated linear regulators or multi-string control. | Lower channel count, digital control, and smaller footprint needed for cost-sensitive consumer displays. | Choose TPS61165DRVR only for single-string designs requiring serial configuration; not a functional replacement for 3-channel operation. |
Compared with LM3431AMHX/NOPB, the LM3431QMHX/NOPB trades 2 mV higher SNSx offset for identical AEC-Q100 Grade 1 qualification and lower cost; versus TPS61165DRVR, it provides true 3-channel analog regulation but lacks digital interface and requires external transistor drivers.
Availability
LM3431QMHX/NOPB is available at Aetrix Electronics and suitable for automotive infotainment displays, small-to-medium format industrial HMIs, and avionics backlighting requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.
Supply support for LM3431QMHX/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 delivers integrated LED backlight drivers for automotive and industrial displays, combining boost conversion and precision linear current regulation to minimize board space and improve system efficiency.
FAQ
What is the maximum LED string current supported by the LM3431QMHX/NOPB?
The LM3431QMHX/NOPB supports LED string currents exceeding 200 mA per channel using external NPN transistors or MOSFETs. Its NDRVx outputs provide up to 20 mA source and 8 mA sink current, enabling robust base/gate drive for high-current external switches. Total system current depends on thermal design and external component ratings, but the IC's channel regulation remains accurate within its specified offset and bandwidth limits.
How does the LM3431QMHX/NOPB prevent audible noise during PWM dimming?
The LM3431QMHX/NOPB eliminates audible noise by maintaining constant cathode voltage regulation via the CFB pin during LED-on periods, decoupling output voltage from dimming duty cycle. Unlike conventional boost controllers that modulate output voltage during dimming, this architecture avoids inductor and capacitor vibration caused by large AC ripple, ensuring silent operation even at 25 kHz dimming frequencies.
What protection features does the LM3431QMHX/NOPB include for LED arrays?
The LM3431QMHX/NOPB integrates LED short detection (SC pin threshold 6.0 V), LED open detection (SC clamp at 3.5 V), thermal shutdown at 160°C (THM pin), overvoltage protection via AFB (2.0 V threshold), and programmable fault delay (DLY pin). These features collectively safeguard the LED array and driver from catastrophic failures due to wiring faults, thermal runaway, or component degradation.
Can the LM3431QMHX/NOPB operate with input voltage equal to or greater than the LED string forward voltage?
No - the LM3431QMHX/NOPB requires VIN to remain at least 1 V below the set output voltage to maintain continuous conduction mode and avoid pulse skipping. When VIN approaches or exceeds the nominal output voltage, the boost controller stops switching, causing unregulated output and increased NDRVx power dissipation. TI recommends restricting VIN to ensure minimum on-time remains above 170 ns for stable regulation.
What is the purpose of the AFB and CFB pins in the LM3431QMHX/NOPB?
The AFB pin regulates output voltage during LED-off periods (startup, dimming off-cycles) using sample-hold logic referenced to SS/SH, while the CFB pin regulates LED cathode voltage at 1.71 V during LED-on periods. This dual-feedback architecture ensures stable output voltage across dimming transitions and minimizes headroom loss, improving overall system efficiency and eliminating audible noise.
LM3431QMHX/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:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-HTSSOP
LM3431QMHX/NOPB FAQ
1.How can I place an order for LM3431QMHX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3431QMHX/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 LM3431QMHX/NOPB reliable?
The price and inventory of LM3431QMHX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3431QMHX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3431QMHX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3431QMHX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3431QMHX/NOPB?
LM3431QMHX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3431QMHX/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 LM3431QMHX/NOPB?
For technical support, including LM3431QMHX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3431QMHX/NOPB requirements.
6.How does Aetrix verify that LM3431QMHX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3431QMHX/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 LM3431QMHX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3431QMHX/NOPB?
All LM3431QMHX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3431QMHX/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 LM3431QMHX/NOPB part is unused and in its original packaging.
Return procedure for LM3431QMHX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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