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Texas Instruments LM3430SD
- Part No.:
- LM3430SD
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LM3430SD.pdf
- Description:
- IC LED DRIVER CTRLR PWM 12WSON
- Quantity:
- Payment:
- Shipping:
Inventory:4,180
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Product details
Overview
LM3430SD from Texas Instruments is a high-voltage, current-mode boost controller for LED backlighting applications. It features a 1A peak gate driver, internal 40V startup regulator, programmable UVLO with hysteresis, and supports up to 2 MHz switching frequency with <100 ns propagation delay. Designed for notebook LCD panel backlight drivers in conjunction with LM3432, it operates from 6V to 40V input and delivers >90% duty cycle capability.
For engineers reviewing the LM3430SD datasheet, LM3430SD pinout, LM3430SD application, or LM3430SD equivalent, key selection criteria include its 12-lead LLP (3mm × 3mm) package, VDHC dynamic headroom control interface, cycle-by-cycle current limiting at 0.5V CS threshold, and external resistor–set oscillator frequency (e.g., 600 kHz with 27.4 kΩ).
Technical Context
The LM3430SD implements fixed-frequency current-mode PWM control with slope compensation to prevent subharmonic oscillation above 50% duty cycle. Its error amplifier uses a 1.25V internal reference and drives the COMP pin with 75 dB DC gain and 4 MHz GBW for loop stability.
It integrates a wide-input (6–40V) linear startup regulator delivering regulated 7V on VCC, an under-voltage lockout circuit with 20 µA hysteresis current source on UVLO, and thermal shutdown at 165°C with 25°C hysteresis. The OUT pin provides 1A peak drive with 18 ns rise/15 ns fall time into 1 nF load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 6V to 40V - enables direct connection to automotive battery or multi-cell Li-ion stacks without pre-regulation. |
| fSW Range | 170 kHz to 2 MHz - set by RT resistor; 600 kHz typical with 27.4 kΩ, balancing inductor size and efficiency. |
| FB Voltage | 1.25V ±25 mV - precision reference for output voltage regulation via external resistor divider. |
| CS Threshold | 0.5V ±50 mV - cycle-by-cycle current limit trigger point, enabling accurate MOSFET overcurrent protection. |
| Max Duty Cycle | 90% to 95% - supports high step-up ratios required for white LED strings (e.g., 33V from 9V input). |
| OUT Drive | 1A peak sink/source - directly drives N-channel MOSFET gates without external buffer in most LED boost designs. |
| Thermal Shutdown | 165°C with 25°C hysteresis - protects IC during overload or poor heatsinking; auto-recovery after cooldown. |
Pinout & Package
LM3430SD is housed in a thermally enhanced 12-lead LLP package (3 mm × 3 mm, 0.5 mm pitch) with exposed thermal pad (DAP) requiring PCB ground connection for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VDHC | Dynamic Headroom Control Input | Accepts analog voltage from LM3432 to adjust output voltage in real time for LED efficiency optimization. |
| 2 VIN | Main Power Input | Connects to 6–40V supply; powers internal startup regulator and bias circuits. |
| 3 FB | Feedback Input | Inverting input of error amplifier; referenced to 1.25V internal reference for output voltage regulation. |
| 4 COMP | Compensation Node | Error amplifier output; connects to FB via RC network for loop stability and transient response tuning. |
| 5 VCC | Internal Regulator Output | 7V regulated output (6.6–7.4V); bypassed with ceramic capacitor; powers internal logic and gate driver. |
| 6 OUT | MOSFET Gate Driver Output | 1A peak push-pull output driving external low-side N-MOSFET gate. |
| 7 GND | System Ground Reference | Analog and power ground return; connects to DAP for thermal conduction. |
| 8 UVLO | Under-Voltage Lockout Input | Resistor-divider node setting startup/shutdown thresholds; 20 µA hysteresis current source enables clean enable/disable. |
| 9 CS | Current Sense Input | Inputs MOSFET source/sense resistor voltage; triggers cycle-by-cycle shutdown at 0.5V. |
| 10 RT/SYNC | Oscillator & Sync Input | Resistor sets fSW (170 kHz–2 MHz); AC-coupled external clock synchronizes switching. |
| 11 SS | Soft-Start Control | 10 µA current source charges external capacitor to ramp COMP voltage and limit inrush current. |
| 12 NC | No Connect | Not internally bonded; must remain unconnected. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Soft-Start | External capacitor on SS pin controls startup ramp rate and limits inrush current into output capacitors. |
| Internal 40V Startup Regulator | Eliminates need for external bias supply; delivers 7V/35 mA to VCC across full 6–40V VIN range. |
| 1A Peak Gate Driver | Directly drives standard N-channel MOSFETs (e.g., SO-8, 60V) without external buffers in LED boost topologies. |
| Programmable UVLO with Hysteresis | 20 µA current source on UVLO pin ensures clean, bounce-free enable/disable with user-defined thresholds. |
| Slope Compensation | Internally generated 105 mV (typ) sawtooth ramp prevents subharmonic oscillation in >50% duty cycle operation. |
| External Synchronization | AC-coupled sync input accepts external clocks > fSW; enables EMI reduction via frequency dithering or system-level timing alignment. |
Applications
| LCD Notebook Backlight Driver | Automotive Display Backlight |
|---|---|
Use Scenario: Driving 6 parallel strings of 8 white LEDs (20 mA each) in a 15.6-inch notebook display powered from 3S Li-ion battery (9–12.6V). IC Role / Device Role / Timing Role: Current-mode boost controller regulating 33V output; provides VDHC interface to LM3432 for dynamic dimming and headroom adjustment. Use Value: Enables >90% efficiency across input range and dimming levels; soft-start prevents inrush stress on LED strings and input caps. | Use Scenario: Powering TFT-LCD instrument cluster backlight in 12V automotive systems with cold-crank tolerance down to 6V. IC Role / Device Role / Timing Role: High-voltage boost controller with UVLO hysteresis and thermal shutdown; maintains stable LED current despite battery transients. Use Value: Wide 6–40V input range and 165°C thermal shutdown ensure reliable operation during load dump or cranking events. |
| Industrial Panel PC Backlight | Medical Imaging Display Supply |
Use Scenario: Generating 50V output for 12×6 LED string configuration in ruggedized industrial HMI with 8–21V DC input. IC Role / Device Role / Timing Role: SEPIC/boost topology controller supporting high step-up ratio; uses RT resistor for 1 MHz switching to minimize inductor size. Use Value: 2 MHz max fSW allows compact magnetics; cycle-by-cycle current limit protects against open-string faults. | Use Scenario: Precision LED backlight for diagnostic-grade medical monitor requiring stable luminance and low EMI in EMC-sensitive environments. IC Role / Device Role / Timing Role: Synchronizable boost controller locked to system clock to avoid beat frequencies in imaging frame timing. Use Value: External sync capability eliminates switching noise interference with image sensor readout and ADC sampling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3430MM | Same die, MSOP-10 package (3 mm × 3 mm, 0.5 mm pitch); no exposed pad; lower thermal performance (θJA = 160°C/W vs. 122°C/W). | Limited to lower-power LED strings (<150 mA) or forced-air-cooled designs due to reduced thermal dissipation. | Select LM3430MM only when board space constraints prohibit LLP footprint or thermal load is below 0.8 W. |
| TPS40210DGQ | Current-mode controller with integrated 1.5A gate driver; wider fSW range (100 kHz–1.2 MHz); no VDHC pin or dedicated LED-specific features. | General-purpose boost/SEPIC; lacks LM3432 companion interface and dynamic headroom control for LED efficiency tuning. | Choose TPS40210DGQ for non-LED applications or where higher gate drive current is needed, but expect added loop compensation effort. |
Compared with LM3430MM, the LM3430SD offers superior thermal management via its exposed pad and supports higher continuous output current; versus TPS40210DGQ, it delivers LED-optimized features like VDHC and tighter FB reference (±2%) but trades off maximum gate drive strength.
Availability
LM3430SD is available at Aetrix Electronics and suitable for LCD backlighting, automotive display power, and industrial panel PC applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM3430SD 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 over 50 years of innovation in power conversion ICs.
The LM3430SD belongs to TI's LED backlight controller product line, engineered specifically for high-efficiency, dynamically adjustable boost converters in portable and automotive displays.
FAQ
What is the function of the VDHC pin on the LM3430SD?
The VDHC pin on the LM3430SD is a proprietary analog input that accepts a control voltage from the LM3432 to dynamically adjust the output voltage in real time. This enables optimal LED headroom management-reducing power loss and improving efficiency across varying LED forward voltage and temperature conditions. When unused, the VDHC pin must be left open-circuit per the LM3430SD datasheet.
Can the LM3430SD operate without an external VCC supply?
Yes, the LM3430SD can operate without an external VCC supply because it integrates a high-voltage startup regulator that accepts 6–40V directly on VIN and delivers a regulated 7V output on the VCC pin. An external 0.1–100 µF ceramic capacitor on VCC is mandatory for stability. If an external bias rail (7.5–14V) is available, VCC and VIN may be tied together to bypass the internal regulator and improve efficiency.
What is the minimum recommended value for the RT resistor on the LM3430SD?
The minimum recommended RT resistor value for the LM3430SD is 16.2 kΩ, which sets the maximum oscillator frequency to approximately 990 kHz (typical). Using a lower resistance risks exceeding the 2 MHz absolute maximum switching frequency limit and may cause instability or increased gate driver losses. The LM3430SD datasheet specifies RT values from 16.2 kΩ to 84.5 kΩ for guaranteed operation across temperature and process variation.
How does the LM3430SD implement cycle-by-cycle current limiting?
The LM3430SD implements cycle-by-cycle current limiting by comparing the voltage on the CS pin to an internal 0.5V threshold. When the sensed voltage exceeds this level-indicating peak switch current has reached the programmed limit-the PWM comparator immediately terminates the gate drive pulse. Leading-edge blanking (65 ns) suppresses noise during MOSFET turn-on, and the CS pin's 40–75 Ω sink impedance ensures fast discharge for accurate per-cycle detection in the LM3430SD.
Is the LM3430SD pin-compatible with other members of the LM343x family?
No, the LM3430SD is not pin-compatible with other LM343x devices such as LM3432 or LM3433. While LM3432 is a complementary 6-channel LED driver designed to interface with LM3430SD via VDHC, it uses a 24-pin QFN package with entirely different pin functions and layout. The LM3430SD's 12-pin LLP footprint and signal mapping (e.g., VDHC on Pin 1, NC on Pin 12) are unique to its controller role and have no mechanical or electrical pin equivalence within the family.
LM3430SD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- DC DC Controller
- Topology:
- SEPIC, Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 6V
- Voltage - Supply (Max):
- 40V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 2MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-WSON (3x3)
LM3430SD FAQ
1.How can I place an order for LM3430SD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3430SD 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 LM3430SD reliable?
The price and inventory of LM3430SD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3430SD is usually 5 days.
3.What payment methods are accepted for LM3430SD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3430SD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3430SD?
LM3430SD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3430SD 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 LM3430SD?
For technical support, including LM3430SD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3430SD requirements.
6.How does Aetrix verify that LM3430SD is sourced from the original manufacturer or authorized distributors?
All LM3430SD 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 LM3430SD meets industry standards.
7.What is the process for return or replacement of LM3430SD?
All LM3430SD units undergo pre-shipment inspection (PSI). If there is an issue with LM3430SD, 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 LM3430SD part is unused and in its original packaging.
Return procedure for LM3430SD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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