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Texas Instruments LM3421MH/NOPB
- Part No.:
- LM3421MH/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3421MH/NOPB.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:216
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Product details
Overview
LM3421MH/NOPB from Texas Instruments is a high-voltage N-channel MOSFET controller for constant-current LED drivers, supporting buck, boost, buck-boost, and SEPIC topologies. It operates from 4.5 V to 75 V input, features predictive off-time (PRO) control, 2-Ω/1-A peak gate drive, and high-side adjustable current sensing with 1.24 V reference. It enables precise LED current regulation in automotive lighting and outdoor area SSL systems.
For engineers reviewing the LM3421MH/NOPB datasheet, LM3421MH/NOPB pinout, LM3421MH/NOPB application, or LM3421MH/NOPB equivalent, key selection considerations include its 75 V VIN rating, PRO control architecture, high-side differential current sense interface, programmable switching frequency up to 2 MHz, and thermal shutdown at 165°C - all critical for robust, high-efficiency LED driver design.
Technical Context
The LM3421MH/NOPB implements Predictive Off-Time (PRO) control - a hybrid of peak current-mode control and input-voltage-proportional off-timer - enabling stable loop compensation and inherent input voltage feed-forward without sub-harmonic oscillation risk. Its high-side transconductance amplifier (20 mA/V gM) senses LED current via external HSP/HSN resistors, while the CSH pin regulates to 1.24 V for accurate current setting.
It integrates a 6.9 V internal LDO regulator (VCC), cycle-by-cycle current limiting via IS pin (245 mV threshold), analog and PWM dimming support (nDIM and DDRV), and dual protection: input UVLO (1.24 V threshold with 23 µA hysteresis current) and output OVLO (OVP pin, same threshold/hysteresis). The 16-pin HTSSOP package includes thermal pad for enhanced power dissipation (RθJA = 38.9°C/W).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4.5 V to 75 V - supports wide-input industrial, automotive, and mains-derived LED drivers without pre-regulation. |
| Switching Frequency | Up to 2 MHz - enables compact magnetics and low-output-ripple designs using small inductors and capacitors. |
| Current Sense Reference | 1.24 V on CSH - sets LED current accuracy via external resistor network; enables analog dimming by modulating CSH voltage. |
| GATE Driver Strength | 2 Ω sourcing / 4.5 Ω sinking - drives N-channel MOSFETs up to 1 A peak, reducing switching losses in high-current LED strings. |
| Thermal Shutdown | 165°C with 25°C hysteresis - protects against sustained overloads while allowing safe recovery after cooling. |
| UVLO & OVLO Threshold | 1.24 V with 23 µA hysteresis current - provides precise, temperature-stable input undervoltage and output overvoltage lockout. |
| Package | HTSSOP-16 (5.00 mm × 4.40 mm) with exposed thermal pad - optimized for thermal performance in high-power LED driver PCB layouts. |
Pinout & Package
LM3421MH/NOPB uses a 16-pin HTSSOP package (PWP) with exposed thermal pad (DAP) connected to AGND/PGND star ground. Pin numbering follows standard top-view layout; thermal pad must be soldered for thermal integrity and electrical grounding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Main input supply | Bypassed with 100 nF ceramic capacitor to AGND; powers internal start-up regulator and high-voltage circuitry. |
| EN (2) | Enable control | Logic-level input: ≥2.4 V enables operation; ≤0.8 V forces zero-current shutdown (ISD = 0.1 µA typical). |
| COMP (3) | Error amplifier output | Connects to RC compensation network; regulates CSH to 1.24 V for stable current loop control. |
| CSH (4) | Current sense reference | Sinks 100 µA typical signal current; regulated to 1.24 V for LED current setting and analog dimming interface. |
| RCT (5) | Off-time timing | External RC network sets predictive off-time and thus switching frequency; VRCT = VIN/25 (565 mV @ VIN=14 V). |
| AGND (6) | Analog ground reference | Reference for CSH, COMP, RCT, OVP; connected to PGND via DAP copper pad for low-noise sensing. |
| OVP (7) | Output overvoltage detection | Resistor divider from VO sets OVLO threshold at 1.24 V; 23 µA hysteresis current enables clean latch-off recovery. |
| nDIM (8) | PWM dimming / UVLO input | Accepts PWM signal for LED dimming; also programs VIN UVLO threshold (1.24 V turn-on) via resistor divider. |
| VCC (12) | Internal LDO output | 6.9 V regulated supply (7.35 V max); bypassed with 2.2–3.3 µF ceramic capacitor to PGND for gate driver stability. |
| GATE (11) | Main MOSFET gate driver | 2 Ω source / 4.5 Ω sink capability; drives N-channel switch with fast rise/fall times and cycle-by-cycle current limit. |
| PGND (10) | Power ground return | Return path for GATE and DDRV drivers; connected to AGND through DAP for minimized ground bounce in high-di/dt paths. |
| DDRV (9) | Dimming FET gate driver | Drives external N-channel dimming MOSFET; 13.5 Ω source / 3.5 Ω sink resistance enables fast PWM dimming response. |
| IS (13) | Main switch current sense | Inputs MOSFET RDS(on) voltage or external sense resistor; triggers cycle-by-cycle current limit at 245 mV threshold. |
| HSP (15) / HSN (16) | High-side LED current sense | Differential inputs to transconductance amplifier (gM = 20 mA/V); enable floating LED string sensing with ±7 mV offset. |
Key Features
| Feature | Design Value |
|---|---|
| Predictive Off-Time (PRO) Control | Eliminates sub-harmonic oscillation at any duty cycle; enables stable high-VOUT/VIN boost operation without complex compensation. |
| High-Side Adjustable Current Sense | 1.24 V reference with 20 mA/V transconductance amplifier allows precise, noise-immune LED current regulation in floating topologies. |
| Integrated Protection Suite | Input UVLO, output OVLO, cycle-by-cycle current limit, thermal shutdown, and zero-current shutdown reduce external component count. |
| 2 MHz Capable Gate Driver | 2 Ω sourcing / 4.5 Ω sinking strength supports fast-switching, high-efficiency MOSFETs in compact LED driver designs. |
| Flexible Dimming Interface | Simultaneous analog dimming (via CSH) and PWM dimming (via nDIM and DDRV) enable >1000:1 dimming ratio in high-end lighting. |
Applications
| Automotive Headlamp Drivers | Outdoor Area Lighting |
|---|---|
|
Use Scenario: High-brightness LED headlamps in 12 V/24 V vehicle systems requiring EMI-compliant, thermally robust constant-current regulation. IC Role / Device Role / Timing Role: N-channel controller implementing boost topology to drive 40–80 V LED strings from variable battery input; PRO control maintains stability across cold-crank (6 V) to load-dump (40 V) conditions. Use Value: Enables single-chip solution with no external current-sense op-amp; 75 V VIN rating eliminates need for pre-regulator; thermal shutdown prevents LED degradation during prolonged high-ambient operation. |
Use Scenario: Streetlight and parking lot luminaires powered from 120/277 VAC via offline PFC front-end, driving multi-string high-power LEDs. IC Role / Device Role / Timing Role: Buck-boost controller regulating constant current into parallel LED strings; high-side sensing isolates LED cathode from system ground for simplified thermal management. Use Value: 1.24 V current sense reference minimizes I2R loss in sense resistor; programmable frequency avoids audible noise; OVP protection safeguards against open-circuit LED string failure. |
| Industrial Machine Vision Lighting | Architectural Accent Lighting |
|
Use Scenario: High-intensity strobed LED arrays used in factory automation cameras requiring microsecond-level PWM dimming precision and repeatable intensity. IC Role / Device Role / Timing Role: Controller with dedicated DDRV pin driving external N-FET for fast, jitter-free PWM dimming; nDIM accepts logic-level signals up to 2 MHz. Use Value: DDRV's 3.5 Ω sink resistance ensures <100 ns fall time; PRO control delivers consistent LED current pulse amplitude independent of input ripple or bus transients. |
Use Scenario: Low-profile linear LED fixtures for retail and hospitality environments where thermal envelope and EMI are tightly constrained. IC Role / Device Role / Timing Role: SEPIC topology controller delivering constant current to 24 V LED modules from 12 V DC input; compact 2 MHz operation reduces inductor size and acoustic noise. Use Value: HTSSOP-16 package with thermal pad enables conduction-cooled mounting on aluminum extrusions; 2-Ω GATE driver minimizes MOSFET switching losses at high frequency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar N-channel LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3423MH/NOPB | 20-pin HTSSOP; adds FLT fault flag, TIMR timer, LRDY LED ready flag, DPOL dim polarity control, and RPD resistor pulldown. | Required for designs needing fault latching, status monitoring, or series-PFET dimming; not pin-compatible due to extra pins and different pinout. | Select LM3423MH/NOPB only if fault reporting, timer-based safety shutdown, or dual-dimming-path flexibility is required - otherwise LM3421MH/NOPB offers lower cost and simpler layout. |
| LT3761EFE#PBF | 40 V max VIN; integrated 7.5 V bias supply; higher 3.3 A gate drive; requires external oscillator for sync; no high-side sense amplifier. | Better suited for lower-voltage, higher-current boost LED drivers (<40 V input); lacks native high-side sensing, requiring external op-amp for floating strings. | Choose LT3761EFE#PBF when driving high-current (≥3 A), low-VOUT LED loads from ≤40 V sources and board space permits external compensation components. |
Compared with LM3423MH/NOPB, LM3421MH/NOPB offers identical core control architecture and 75 V rating but omits fault/status flags and dim polarity control - making it optimal for cost-sensitive, functionally streamlined LED drivers. Versus LT3761EFE#PBF, LM3421MH/NOPB provides superior high-voltage resilience and integrated high-side sensing, trading off gate drive strength and sync capability.
Availability
LM3421MH/NOPB is available at Aetrix Electronics and suitable for automotive headlamps, outdoor area lighting, and industrial machine vision systems requiring stable component supply, long-term manufacturability, and TI-qualified reliability.
Supply support for LM3421MH/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 expertise in LED driver ICs and automotive-grade power solutions.
The LM3421MH/NOPB belongs to TI's LM342x family of high-voltage N-channel LED controllers, designed specifically for flexible, efficient constant-current regulation in buck, boost, buck-boost, and SEPIC LED driver topologies across automotive, industrial, and architectural lighting.
FAQ
What topology configurations does the LM3421MH/NOPB support?
The LM3421MH/NOPB supports buck, boost, buck-boost, and SEPIC topologies for constant-current LED drivers. Its high-side current sense architecture and PRO control enable stable operation across all four configurations without topology-specific compensation changes. The device drives ground-referenced N-channel MOSFETs, and its 75 V VIN rating makes it especially suitable for boost and buck-boost implementations in automotive and outdoor lighting where input voltage varies widely. LM3421MH/NOPB does not require external op-amps for current sensing in floating LED strings.
How does the LM3421MH/NOPB implement analog dimming?
The LM3421MH/NOPB implements analog dimming by modulating the voltage on the CSH pin, which is internally regulated to 1.24 V. When an external current source or potentiometer is connected between CSH and AGND, it alters the signal current (ICSH) flowing out of CSH, directly scaling the LED current setpoint. This method achieves smooth, flicker-free dimming without PWM frequency artifacts. The high-side sense amplifier (HSP/HSN) remains active, preserving accuracy and noise immunity. LM3421MH/NOPB supports analog dimming down to ~10% of full scale while maintaining regulation stability.
What is the purpose of the RCT pin on the LM3421MH/NOPB?
The RCT pin on the LM3421MH/NOPB sets the predictive off-time and thus the switching frequency via an external resistor-capacitor network. The internal circuit generates VRCT = VIN/25 (e.g., 565 mV at VIN = 14 V), and the RC time constant determines tOFF(min), which ranges from 35 ns to 75 ns depending on temperature. This enables programmable frequencies up to 2 MHz while maintaining input-voltage feed-forward behavior. LM3421MH/NOPB requires careful PCB layout: RCT must be decoupled from noisy nodes and routed away from high-di/dt traces to avoid jitter or frequency instability.
Does the LM3421MH/NOPB include built-in overvoltage protection?
Yes, the LM3421MH/NOPB includes dedicated overvoltage protection (OVP) via the OVP pin. A resistor divider from the LED output (VO) to AGND programs the OVLO threshold at 1.24 V, with hysteresis provided by a 23 µA internal current source. When triggered, the controller disables the GATE driver and enters latched shutdown until EN is cycled. This protects downstream LEDs and capacitors from catastrophic failure during open-circuit or feedback-loop faults. LM3421MH/NOPB does not auto-recover - manual reset via EN is required - ensuring safety-critical systems remain disabled until fault condition is resolved.
What thermal management features does the LM3421MH/NOPB provide?
The LM3421MH/NOPB integrates thermal shutdown at 165°C with 25°C hysteresis, preventing permanent damage during overload or poor heatsinking. Its HTSSOP-16 package includes an exposed thermal pad (DAP) that must be soldered to a PCB copper pour connected to both AGND and PGND for optimal heat dissipation (RθJA = 38.9°C/W). The device also supports zero-current shutdown (ISD = 0.1 µA typical) via EN pin grounding, minimizing standby power. LM3421MH/NOPB's thermal design enables reliable operation in enclosed luminaires and under-hood automotive environments when layout guidelines - including minimum DAP solder mask opening and thermal via count - are followed.
LM3421MH/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 4.5V
- Voltage - Supply (Max):
- 75V
- Voltage - Output:
- 3V ~ 72V
- Current - Output / Channel:
- -
- Frequency:
- 2MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-HTSSOP
LM3421MH/NOPB FAQ
1.How can I place an order for LM3421MH/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3421MH/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 LM3421MH/NOPB reliable?
The price and inventory of LM3421MH/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3421MH/NOPB is usually 5 days.
3.What payment methods are accepted for LM3421MH/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3421MH/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3421MH/NOPB?
LM3421MH/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3421MH/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 LM3421MH/NOPB?
For technical support, including LM3421MH/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3421MH/NOPB requirements.
6.How does Aetrix verify that LM3421MH/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3421MH/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 LM3421MH/NOPB meets industry standards.
7.What is the process for return or replacement of LM3421MH/NOPB?
All LM3421MH/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3421MH/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 LM3421MH/NOPB part is unused and in its original packaging.
Return procedure for LM3421MH/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3421MH/NOPB Tags
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BCR402RE6327HTSA1
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
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BCR420UE6327HTSA1
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BCR421UE6327HTSA1
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LYT1604D-TL
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HV9910CLG-G
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CL2N8-G
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BCR420UW6-7
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BCR421UW6-7
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BCR420UFD-7
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