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Texas Instruments LM3423MH/NOPB
- Part No.:
- LM3423MH/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3423MH/NOPB.pdf
- Description:
- IC LED DRIVER CTRLR PWM 20HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:536
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Product details
Overview
LM3423MH/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 dual dimming (PWM + analog). Used in outdoor SSL and automotive LED lighting systems requiring precise current regulation up to 5 A.
For engineers reviewing the LM3423MH/NOPB datasheet, LM3423MH/NOPB pinout, LM3423MH/NOPB application, or LM3423MH/NOPB equivalent, key selection considerations include high-side differential current sensing (1.24 V threshold), fault flag/timer support, thermal shutdown (165°C), and HTSSOP-20 package compatibility with PCB layout for high-voltage LED driver designs.
Technical Context
The LM3423MH/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 feed-forward without sub-harmonic oscillation at high duty cycles. Its high-side transconductance amplifier (20 mA/V gM) senses LED current differentially across HSP/HSN with ±7 mV offset voltage.
It integrates a 6.9 V internal LDO regulator (VCC), programmable switching frequency up to 2 MHz via RCT, cycle-by-cycle current limiting on IS pin (245 mV threshold), and dedicated DDRV output for external dimming FET control. The device includes LED-ready (LRDY) and fault (FLT) open-drain flags, OVP protection (1.24 V threshold), and zero-current shutdown via RPD pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4.5 V to 75 V - supports wide-input industrial and automotive LED systems without pre-regulation. |
| Switching Frequency | Up to 2 MHz - enables compact magnetics and high-density LED driver layouts. |
| Current Sense Threshold | 1.24 V (CSH) - sets precise LED current via external sense resistor; low offset improves accuracy. |
| GATE Drive Strength | 2 Ω sourcing / 1.3 Ω sinking - drives N-channel MOSFETs with fast rise/fall times for high-efficiency operation. |
| Thermal Shutdown | 165°C with 25°C hysteresis - protects against sustained overload while allowing brief transient overloads. |
| OVP Threshold | 1.24 V on OVP pin - programmable output overvoltage lockout prevents LED string damage during open-circuit faults. |
| Fault Timer | Capacitor-programmable via TIMR - latches FLT flag after user-defined delay for reliable fault detection and recovery. |
Pinout & Package
LM3423MH/NOPB is housed in a thermally enhanced 20-pin HTSSOP (PWP) package (6.50 mm × 4.40 mm) with exposed thermal pad (DAP) for star-grounding AGND and PGND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main power input | Bypassed with 100 nF ceramic capacitor to AGND; powers internal start-up regulator. |
| EN | Enable input | Active-high logic input (2.4 V threshold); pulldown resistance 0.245–2.85 MΩ enables zero-current shutdown when grounded. |
| COMP | Error amplifier output | Connects to compensation network (capacitor to AGND); regulates CSH to 1.24 V for current control. |
| CSH | Current sense reference | Sense amplifier output node regulated to 1.24 V; used for analog dimming and current loop stability. |
| HSN / HSP | High-side current sense inputs | Differential inputs to transconductance amplifier; enable floating LED-string current sensing with ±7 mV offset. |
| IS | Main switch current sense | Monitors MOSFET drain or source for cycle-by-cycle current limit (245 mV threshold). |
| RCT | Frequency programming | RC network sets predictive off-time; determines switching frequency up to 2 MHz. |
| AGND / PGND | Analog & power ground | Separate ground returns; connected via DAP copper pad to minimize noise coupling between control and power paths. |
| GATE | Main MOSFET driver output | 2 Ω/1.3 Ω push-pull driver; directly controls gate of high-side or low-side N-channel switch. |
| DDRV | Dimming FET driver | Drives external dimming MOSFET gate; supports fast PWM dimming independent of main regulation loop. |
| nDIM | PWM dimming input | Accepts 1.24 V threshold PWM signal; also programs UVLO via resistor divider from VIN. |
| OVP | Overvoltage protection input | 1.24 V threshold with 23 µA hysteresis current; connects to resistor divider from output to detect open-circuit LED faults. |
| FLT / LRDY | Fault & LED ready flags | Open-drain outputs pulled up to VIN; FLT asserts on overvoltage/thermal fault; LRDY deasserts when LED current is out of regulation. |
| RPD | Resistor pulldown node | Common return for all external resistor dividers (OVP, nDIM); enables zero-current shutdown when pulled to AGND. |
| VCC | Internal regulator output | 6.9 V LDO output; bypassed with 2.2–3.3 µF ceramic capacitor to PGND for stable gate drive supply. |
| Thermal PAD (DAP) | Thermal & ground interface | Exposed copper pad on bottom; must be soldered to PCB thermal plane and star-connected to AGND/PGND for thermal performance and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Predictive Off-Time (PRO) Control | Eliminates sub-harmonic oscillation at >50% duty cycle; simplifies loop compensation and enables stable boost/buck-boost operation across full VIN/VO range. |
| High-Side Differential Current Sensing | 1.24 V reference with ±7 mV offset and 20 mA/V transconductance enables accurate, noise-immune LED current regulation in floating-string configurations. |
| Dual Dimming Support | Hardware PWM (nDIM pin) + analog (CSH pin) dimming - allows flicker-free brightness control from 0.1% to 100% with independent timing domains. |
| Fault Protection Suite | Programmable OVP, thermal shutdown (165°C), cycle-by-cycle current limit, and fault timer with latchable FLT flag ensure robust operation in safety-critical lighting. |
| Integrated Gate Drivers | 2 Ω sourcing / 1.3 Ω sinking GATE driver + 13.5 Ω sourcing / 3.5 Ω sinking DDRV driver - reduce external component count and improve switching efficiency. |
Applications
| Street Lighting | Automotive Headlamps |
|---|---|
|
Use Scenario: Outdoor LED street luminaires operating from 12–48 V DC battery or PoE-powered grid interfaces with wide ambient temperature swings (−40°C to +85°C). IC Role / Device Role / Timing Role: Constant-current controller regulating 1–3 A LED strings in boost topology; PRO control maintains regulation despite input ripple and line transients. Use Value: High-side sensing enables direct connection to floating LED strings; OVP and thermal shutdown prevent field failures due to open-circuit or heatsink degradation. |
Use Scenario: Adaptive front-lighting systems (AFS) requiring dynamic beam shaping via segmented LED arrays with fast PWM dimming and thermal derating. IC Role / Device Role / Timing Role: Primary LED current controller in buck-boost configuration; DDRV pin drives external dimming FETs for zone-specific intensity control. Use Value: Fault flag (FLT) and LED-ready (LRDY) signals provide real-time diagnostics to vehicle ECU; 75 V max VIN withstands load-dump transients per ISO 7637-2. |
| Industrial Area Lighting | Architectural Accent Lighting |
|
Use Scenario: High-bay warehouse fixtures powered from 277 V AC via offline PFC stage, driving 50–100 W LED modules with 0–10 V or DALI dimming interface. IC Role / Device Role / Timing Role: Secondary-side constant-current controller in SEPIC topology; nDIM accepts 0–10 V analog input converted to PWM via external circuitry. Use Value: Adjustable current sense threshold (1.24 V) allows precise calibration across production batches; RCT pin enables frequency tuning to avoid audible noise in sensitive environments. |
Use Scenario: Low-voltage (12–24 V) RGBW architectural strips with independent channel dimming, requiring minimal board space and high thermal reliability. IC Role / Device Role / Timing Role: Channel-specific LED driver controller in buck topology; thermal pad (DAP) enables direct mounting to aluminum extrusion for passive cooling. Use Value: HTSSOP-20 package with exposed thermal pad achieves 36.7°C/W junction-to-ambient; LRDY flag confirms stable current before enabling downstream color-mixing logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3421MH/NOPB | 16-pin HTSSOP; lacks FLT, TIMR, LRDY, DDRV, DPOL pins; no fault flag or dedicated dimming driver. | Suitable for cost-sensitive, non-fault-critical buck-only LED drivers without diagnostic requirements. | Select LM3423MH/NOPB when system-level fault reporting, thermal monitoring, or independent dimming FET control is required. |
| TPS92692QPWPRQ1 | Automotive-grade (AEC-Q100 Grade 1); integrated 5-V bias rail; current sense amplifier with 50-µV offset; no PRO control (uses current-mode). | Designed for ASIL-B automotive headlamp modules with stringent offset and lifetime requirements; requires external compensation. | Choose LM3423MH/NOPB for industrial/commercial designs needing higher VIN (75 V vs. 65 V), PRO control simplicity, and lower BOM count without integrated bias supply. |
Compared with LM3421MH/NOPB, LM3423MH/NOPB adds critical diagnostics (FLT/LRDY) and dimming flexibility (DDRV), while TPS92692QPWPRQ1 trades PRO control for tighter offset and automotive qualification - making LM3423MH/NOPB optimal for non-automotive high-reliability LED systems demanding both intelligence and simplicity.
Availability
LM3423MH/NOPB is available at Aetrix Electronics and suitable for outdoor SSL, automotive lighting, and industrial area lighting requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM3423MH/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 and LED driver innovation since 2008.
The LM342x family was designed specifically for high-voltage, constant-current LED driver applications across buck, boost, buck-boost, and SEPIC topologies - emphasizing design simplicity, thermal robustness, and fault resilience in commercial and industrial lighting.
FAQ
What is the maximum input voltage supported by the LM3423MH/NOPB?
The LM3423MH/NOPB supports an absolute maximum input voltage of 76 V and a recommended operating range of 4.5 V to 75 V. This wide VIN range enables direct integration into 48 V industrial systems, 277 V AC-derived DC rails, and automotive battery architectures including load-dump tolerant designs. The internal start-up regulator ensures reliable operation across this full span without external pre-regulation.
How does the LM3423MH/NOPB implement LED current regulation without an integrated current-sense amplifier?
The LM3423MH/NOPB uses an external high-side differential current sense architecture: HSP and HSN connect across a series sense resistor (RSNS) in the LED string, and the internal transconductance amplifier forces CSH to 1.24 V. This generates a proportional signal current (ICSH) that flows through RCSH, enabling precise ILED = (1.24 V × RHSP) / (RSNS × RCSH). The method avoids ground-referenced sensing limitations and supports floating LED strings.
Can the LM3423MH/NOPB be used in buck topology with high-side switch configuration?
Yes - the LM3423MH/NOPB is explicitly designed for buck, boost, buck-boost, and SEPIC topologies. In buck configurations, it drives a high-side N-channel MOSFET using the GATE output, while the high-side sense inputs (HSP/HSN) monitor current in the LED string. The PRO control architecture maintains stability even at high duty cycles, and the 75 V VIN rating accommodates typical 24–48 V input ranges used in high-power buck LED drivers.
What is the function of the RPD pin on the LM3423MH/NOPB, and how is it used?
The RPD (Resistor Pulldown) pin on the LM3423MH/NOPB serves as the common return node for all external resistor dividers - including those for nDIM (UVLO) and OVP. When RPD is tied to AGND, it enables zero-current shutdown mode: EN is pulled low, GATE and DDRV outputs disable, and quiescent current drops to 0.1 µA. This feature simplifies system-level power sequencing and reduces standby losses in always-on lighting applications.
Does the LM3423MH/NOPB support synchronization to an external clock signal?
No - the LM3423MH/NOPB does not support external clock synchronization. Its Predictive Off-Time (PRO) control architecture relies on an internally generated off-time determined by the RCT network and input voltage, resulting in quasi-constant frequency behavior in boost/buck-boost topologies. While this eliminates sub-harmonic instability and simplifies design, it precludes precise frequency locking to external timing sources - a trade-off accepted for robustness and reduced component count.
LM3423MH/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-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:
- -
- 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:
- 20-HTSSOP
LM3423MH/NOPB FAQ
1.How can I place an order for LM3423MH/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3423MH/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 LM3423MH/NOPB reliable?
The price and inventory of LM3423MH/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3423MH/NOPB is usually 5 days.
3.What payment methods are accepted for LM3423MH/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3423MH/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3423MH/NOPB?
LM3423MH/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3423MH/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 LM3423MH/NOPB?
For technical support, including LM3423MH/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3423MH/NOPB requirements.
6.How does Aetrix verify that LM3423MH/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3423MH/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 LM3423MH/NOPB meets industry standards.
7.What is the process for return or replacement of LM3423MH/NOPB?
All LM3423MH/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3423MH/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 LM3423MH/NOPB part is unused and in its original packaging.
Return procedure for LM3423MH/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3423MH/NOPB Tags
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