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Texas Instruments LM3431MHX/NOPB
- Part No.:
- LM3431MHX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 28-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3431MHX/NOPB.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,534
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Product details
Overview
LM3431MHX/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 ±5 mV SNS amplifier offset voltage, supports 5 V to 36 V input, enables up to 25 kHz PWM dimming with >100:1 contrast ratio, and drives external NPN transistors or MOSFETs for LED strings exceeding 200 mA per channel.
For engineers reviewing the LM3431MHX/NOPB datasheet, LM3431MHX/NOPB pinout, LM3431MHX/NOPB application, or LM3431MHX/NOPB equivalent, key selection criteria include cathode feedback (CFB) regulation, programmable cycle-by-cycle current limit via ILIM, thermal shutdown at 160°C, analog/digital dimming flexibility, and TSSOP-28 exposed-pad package compatibility with high-power LED panel designs.
Technical Context
The LM3431MHX/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 paths-one for LED-off regulation (AFB) and one for LED-on cathode regulation (CFB)-to minimize headroom and maximize efficiency.
Each channel features dedicated SNSx/NDRVx pins with 2 MHz bandwidth amplifiers, ±5 mV offset (–40°C to +125°C), and matched channel-to-channel offset ≤6 mV. Dimming control operates via DIM pin with 0.4 µs minimum internal pulse width, THM thermal monitoring input, and LEDOFF dual-function fault signaling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5 V to 36 V - supports wide automotive and industrial supply rails without external pre-regulation. |
| LED Current Accuracy | ±5 mV SNSx offset voltage - ensures <±2% current matching across channels at full temperature range. |
| Dimming Frequency | Up to 25 kHz - enables flicker-free operation while avoiding audible noise in display backlighting. |
| Boost Switching Frequency | 200 kHz to 1 MHz - adjustable via RT resistor; higher frequencies allow smaller magnetics and faster transient response. |
| Thermal Shutdown Threshold | 160°C - protects IC and LED array under sustained overloads or poor heatsinking conditions. |
| Package Thermal Resistance | θJA = 32°C/W (TSSOP-28 EP) - enables 3.1 W power dissipation at TA = 25°C with JEDEC 4-layer PCB layout. |
| LED Protection Features | Short-circuit detection (SC pin), open-LED fault (AFB OVP), thermal monitor (THM), and programmable fault delay (DLY) - reduces system-level fault handling complexity. |
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 input | Primary supply rail (5–36 V); powers boost controller and internal bias circuitry. |
| PGND | Power ground | High-current return path for boost switch and LED string currents; separate from SGND. |
| VCC | Internal reference output | 5 V ±2.5% regulated supply; requires ≥4.7 µF bypass capacitor to PGND for stability. |
| LG | Boost gate driver | Drives external NFET switch; 0.35 A source / 0.70 A sink capability supports fast switching at high frequency. |
| CS | Boost current sense | Monitors top-side boost sense resistor voltage; used for PWM control and cycle-by-cycle current limiting. |
| SNS1–SNS3 | Channel current feedback | Inputs to precision current-sense amplifiers; each references REFIN to set LED current per string. |
| NDRV1–NDRV3 | Channel drive outputs | Drive bases of external NPN transistors or gates of NFETs; 3.7 V drive voltage supports saturated switching. |
| CFB | Cathode feedback | Regulates LED cathode voltage during LED-on state; 1.71 V typical setpoint minimizes headroom loss. |
| AFB | Anode feedback | Regulates output voltage during LED-off periods (startup/dimming); sets OVP threshold and soft-start reference. |
| DIM | Brightness control | Accepts analog voltage (0–5 V) or digital PWM signal; 0.4 µs minimum pulse width enables high-frequency dimming. |
| THM | LED thermal monitor | Enters standby when pulled below 1.23 V; interfaces directly with NTC thermistor networks on LED board. |
| EN | Enable/UVLO input | Shuts down device below 0.75 V; UVLO threshold programmable via resistor divider for system-level brownout protection. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost + 3-channel linear regulation | Eliminates need for separate boost IC and current sources-reduces BOM count and PCB area in display backlight modules. |
| Cathode feedback (CFB) architecture | Maintains constant cathode voltage during dimming, preventing audible noise and ensuring stable current regulation regardless of LED Vf drift. |
| Programmable fault delay (DLY) | Capacitor-set delay prevents nuisance shutdowns during transient faults; supports automatic restart or latched-off behavior. |
| LED short/open protection | SC pin detects shorts via diode-connected cathodes; AFB-based OVP triggers on open strings-no external comparators required. |
| Thermal shutdown with THM input | Independent junction (160°C) and LED-board (THM <1.23 V) thermal protection-enables dual-point thermal management in high-brightness panels. |
Applications
| Automotive Infotainment Displays | Small to Medium Format Displays |
|---|---|
Use Scenario: TFT-LCD backlight in vehicle head units and digital instrument clusters operating across –40°C to +125°C ambient. IC Role / Device Role / Timing Role: LM3431MHX/NOPB acts as primary LED current controller and boost regulator, managing three independent LED strings with synchronized dimming. Use Value: AEC-Q100 Grade 1 qualification, THM-based LED thermal monitoring, and robust short/open fault detection ensure functional safety compliance and field reliability. |
Use Scenario: Backlight for portable medical monitors, industrial HMI panels, and retail kiosks requiring uniform brightness and low EMI. IC Role / Device Role / Timing Role: LM3431MHX/NOPB provides analog/digital dimming control, CFB-regulated cathode voltage, and soft-start sequencing to prevent inrush current and display flash. Use Value: 25 kHz PWM dimming eliminates visible flicker; 32°C/W θJA enables compact thermal design; TSSOP-28 EP simplifies heatsinking in space-limited enclosures. |
| LED Backlight Panels for Space-Critical Devices | Multi-String Architectures Requiring Channel Matching |
Use Scenario: Thin-profile consumer displays where board height and component count are constrained by mechanical housing. IC Role / Device Role / Timing Role: LM3431MHX/NOPB replaces discrete boost + three op-amp current sources with single-package solution, reducing footprint by >40%. Use Value: Integrated feedforward (FF) pin suppresses output overshoot during PWM transitions; no external compensation needed for stable CFB loop. |
Use Scenario: High-end signage and broadcast monitors demanding precise color balance across multiple LED zones. IC Role / Device Role / Timing Role: LM3431MHX/NOPB delivers matched channel current regulation with ≤6 mV inter-channel offset across –40°C to +125°C. Use Value: REFIN-based current setting allows per-string calibration; SNSx amplifier bandwidth (2 MHz) supports fast dynamic current adjustments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-channel LED driver with integrated boost applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3431AMHX/NOPB | Reduced SNSx offset voltage (±3 mV vs. ±5 mV); improved channel matching (≤4 mV max mismatch). | Better suited for ultra-high-precision color-critical displays where <±1% current matching is required. | Select LM3431AMHX/NOPB when tighter channel matching and lower offset drift over temperature justify cost premium. |
| TPS61165DRVR | Single-channel, 1.2 A boost LED driver; no multi-string current regulation or CFB architecture. | Requires external current sinks for multi-string use; lacks THM, SC, and DLY fault management features. | Choose TPS61165DRVR only for cost-sensitive single-string applications without thermal or fault monitoring requirements. |
Compared with LM3431MHX/NOPB, LM3431AMHX/NOPB improves current accuracy but shares identical pinout, package, and feature set-making it a drop-in upgrade for precision-demanding designs. TPS61165DRVR offers higher per-channel current but cannot replace LM3431MHX/NOPB in 3-string, fault-aware, or thermally monitored systems without significant redesign.
Availability
LM3431MHX/NOPB is available at Aetrix Electronics and suitable for automotive infotainment displays, small-to-medium format industrial HMIs, and space-critical LED backlight panels requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM3431MHX/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 automotive-grade and industrial-grade IC design.
The LM3431 product line was developed specifically for high-reliability LED backlighting in automotive and industrial displays, integrating boost conversion and multi-channel linear current control into a single thermally optimized package.
FAQ
What is the maximum LED string current supported by the LM3431MHX/NOPB?
The LM3431MHX/NOPB supports LED string currents exceeding 200 mA per channel when driving external NPN transistors or MOSFETs. Actual current capability depends on external component selection-including NDRVx drive strength (3.7 V output), thermal design (θJA = 32°C/W), and PCB copper area. At 25°C ambient, continuous operation above 200 mA per string is achievable with proper heatsinking and layout.
How does the CFB pin function in the LM3431MHX/NOPB?
The CFB pin in the LM3431MHX/NOPB provides cathode feedback during LED-on periods, regulating the LED cathode voltage to 1.71 V (typical). This architecture minimizes headroom loss across varying LED forward voltages, improving efficiency and eliminating audible noise during PWM dimming. CFB is active only when LEDs are illuminated; AFB handles regulation during off-states.
Can the LM3431MHX/NOPB operate without an external boost inductor?
No-the LM3431MHX/NOPB requires an external boost inductor, NFET switch, and output diode to form the step-up converter. Its integrated boost controller (LG, CS, AFB, CFB pins) is not self-contained; it relies on these external components to generate the elevated voltage needed for LED strings whose total forward voltage exceeds VIN. Operation below minimum input voltage or without inductor will result in regulation failure.
What is the purpose of the THM pin on the LM3431MHX/NOPB?
The THM pin on the LM3431MHX/NOPB serves as an LED-array thermal monitor input. When pulled below 1.23 V (with hysteresis), the device enters standby mode to protect LEDs from overheating. It interfaces directly with an NTC thermistor network placed near the LED board, enabling localized thermal management independent of IC junction temperature-critical for high-brightness automotive and industrial displays.
Does the LM3431MHX/NOPB support both analog and PWM dimming simultaneously?
The LM3431MHX/NOPB supports either analog dimming (via DC voltage on DIM pin, 0–5 V range) or digital PWM dimming (via square wave on DIM), but not both simultaneously. MODE/F pin selects mode: pulled high for PWM, capacitor-to-ground for analog. Mixing modes is not supported-designers must choose one dimming method per implementation based on EMI, resolution, and control interface requirements.
LM3431MHX/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
LM3431MHX/NOPB FAQ
1.How can I place an order for LM3431MHX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3431MHX/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 LM3431MHX/NOPB reliable?
The price and inventory of LM3431MHX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3431MHX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3431MHX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3431MHX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3431MHX/NOPB?
LM3431MHX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3431MHX/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 LM3431MHX/NOPB?
For technical support, including LM3431MHX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3431MHX/NOPB requirements.
6.How does Aetrix verify that LM3431MHX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3431MHX/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 LM3431MHX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3431MHX/NOPB?
All LM3431MHX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3431MHX/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 LM3431MHX/NOPB part is unused and in its original packaging.
Return procedure for LM3431MHX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3431MHX/NOPB Tags
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