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Texas Instruments LM3551SDX/NOPB
- Part No.:
- LM3551SDX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM3551SDX/NOPB.pdf
- Description:
- IC LED DRIVER RGLTR 1A 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,196
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Product details
Overview
LM3551SDX/NOPB from Texas Instruments is a fixed-frequency, current-mode step-up DC/DC white LED flash driver with two integrated low-side NFETs (FET-T and FET-F), 1.25MHz switching frequency, 2.7–5.5V input range, up to 1A total output current, and flash timeout protection. It enables independent torch/flash/shutdown modes for smartphone camera flash applications.
For engineers reviewing the LM3551SDX/NOPB datasheet, LM3551SDX/NOPB pinout, LM3551SDX/NOPB application, or LM3551SDX/NOPB equivalent, key selection considerations include its dual-FET architecture for mode separation, programmable soft-start for inrush control, OVP trip at 12.4V (typ), shutdown current of 2.55µA (typ), and WSON-14 (4mm × 4mm) package with exposed thermal pad.
Technical Context
The LM3551SDX/NOPB implements a current-mode PWM boost converter with internal 0.165Ω SW FET and separate 0.98Ω (FET-T) and 0.36Ω (FET-F) load disconnect switches. Its 1.25MHz constant-frequency operation enables compact external components, while the 1.265V feedback reference ensures precise LED current regulation across temperature.
Flash timeout is implemented via external capacitor CFTO charged by 1.4µA (typ) current; trip occurs at 1.16V, yielding predictable pulse duration. The SD pin (active-high shutdown logic) features an internal 1.2MΩ pull-up to VIN, enabling default-off behavior without external biasing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 5.5V - supports full Li-ion battery discharge curve without brownout. |
| Switching Frequency | 1.25MHz (typ) - enables use of small 4.7µH inductor and low-ESR ceramic capacitors. |
| Total Output Current | Up to 1A - sum of torch (via FET-T) and flash (via FET-T + FET-F) currents, configurable via RT/RF resistors. |
| Feedback Reference | 1.265V (typ) - tight tolerance (±2.5%) enables accurate LED current setting with external sense resistors. |
| Shutdown Current | 2.55µA (typ) - ultra-low quiescent draw preserves battery life during idle periods. |
| OVP Threshold | 12.4V (typ) - protects LED, capacitor, and inductor during open-circuit or FB fault conditions. |
| Flash Timeout Accuracy | 1.16V ±0.17V trip point with 1.4µA ±0.28µA charging current - supports repeatable flash pulse timing. |
Pinout & Package
LM3551SDX/NOPB is housed in a 14-pin WSON package (NHL0014B) with 4mm × 4mm footprint, 0.65mm pitch, and exposed die-attach pad (DAP) for thermal dissipation. Pin 1–7 and 12–14 are signal terminals; pins 1, 7, and DAP are GND-connected for low-impedance analog/digital ground return.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 9) | Power Input | Accepts 2.7–5.5V supply; connects to input capacitor and battery rail. |
| SD (Pin 5) | Shutdown Control | Active-high logic input; internal 1.2MΩ pull-up to VIN ensures safe default-off state. |
| T/F (Pin 13) | Mode Selection | Logic level selects Torch (low) or Flash (high); no internal pull-up/down. |
| FET-T (Pin 14) | Torch FET Drain | Connects to torch-current sense resistor; 0.98Ω RDSON supports ≤200mA continuous current. |
| FET-F (Pin 2) | Flash FET Drain | Connects to flash-current sense resistor; 0.36Ω RDSON supports ≤500mA pulsed current. |
| SW (Pin 8) | Boost Switch Node | Drives external inductor; rated for 20V max, 2.1A switch current limit. |
| FB (Pin 4) | Current Sense Input | Monitors voltage drop across RT/RF to regulate LED current at 1.265V reference. |
| VC (Pin 3) | Compensation Node | Connects RC/CC network to stabilize loop; error amp transconductance = 135µmho. |
| FTO (Pin 12) | Flash Timeout Timing | Sinks 1.4µA to charge external CFTO; voltage trip at 1.16V defines max flash duration. |
| SS (Pin 11) | Soft-Start Control | Charged by 11.5µA current source to ramp reference and limit inrush current. |
| GND (Pins 1,7,DAP) | Ground Return | Analog/digital ground common point; DAP must be soldered for thermal performance (θJA = 37.3°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent low-side FETs | FET-T (0.98Ω) and FET-F (0.36Ω) enable hardware-separated torch/flash paths with no shared current path. |
| Programmable flash timeout | External CFTO sets precise flash pulse duration (e.g., 1µF → ~860ms), preventing LED overdrive during controller faults. |
| True load disconnect in shutdown | Both FETs and feedback network are isolated from VIN, reducing leakage to <3µA and eliminating standby current paths. |
| Integrated over-voltage protection | OVP triggers at 12.4V (typ), clamping output by disabling SW FET and entering hiccup mode to protect external components. |
| 1.25MHz constant-frequency PWM | Enables predictable EMI filtering and allows use of miniature 4.7µH shielded inductors with <10mΩ DCR. |
Applications
| Smartphone Camera Flash | Digital Still Camera (DSC) Flash |
|---|---|
Use Scenario: High-intensity, short-duration illumination for mobile phone rear-facing cameras under low-light conditions. IC Role / Device Role / Timing Role: LM3551SDX/NOPB acts as the primary flash driver, regulating 700mA–1A pulsed current into Luminus LXM-2P701 LEDs with precise 100–500ms flash timing. Use Value: Dual-FET architecture isolates flash current path from torch circuitry, preventing cross-talk and enabling simultaneous preview/torch + flash burst capability. | Use Scenario: Compact, battery-powered digital still cameras requiring consistent flash intensity across varying battery voltages. IC Role / Device Role / Timing Role: LM3551SDX/NOPB serves as the regulated boost driver for Sharp GM5BW05340A flash LEDs, maintaining stable 1A output despite 3.0–4.2V Li-ion sag. Use Value: 1.25MHz switching frequency minimizes inductor size (4.7µH) and enables PCB space savings critical in slim DSC form factors. |
| Camcorder Torch Mode | PDA Camera Flash |
Use Scenario: Continuous low-power illumination for video recording in dim environments using handheld camcorders. IC Role / Device Role / Timing Role: LM3551SDX/NOPB operates in Torch mode (T/F = low), delivering 200mA through FET-T only for sustained 30+ minute runtime. Use Value: Independent FET-T path eliminates flash-mode switching losses, improving efficiency by >15% versus shared-path alternatives during continuous operation. | Use Scenario: Low-volume, high-reliability PDA platforms needing robust flash functionality with minimal BOM count. IC Role / Device Role / Timing Role: LM3551SDX/NOPB integrates boost conversion, current regulation, OVP, and timeout into single WSON-14 package, replacing 6+ discrete components. Use Value: Exposed DAP and 37.3°C/W θJA allow full 1A operation at TA = 70°C without derating-critical for sealed PDA enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED flash driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3552SDX/NOPB | Replaces SD pin with EN pin (active-high enable); identical specs otherwise; same WSON-14 package. | Requires active-high system control signal instead of active-high shutdown; no change to torch/flash timing or current capability. | Select LM3552SDX/NOPB when host MCU GPIO drives enable logic high; LM3551SDX/NOPB preferred for default-off systems with pull-up-free control. |
| TPS61310DSKR | Single-FET boost driver (no integrated torch/flash FETs); requires external MOSFETs; 1.5A switch current limit; 2.5–5.5V input. | Lacks hardware torch/flash separation and flash timeout; needs external timing circuitry for pulse control. | Choose TPS61310DSKR only if system-level timing is handled externally and dual-FET integration is not required. |
Compared with LM3552SDX/NOPB, LM3551SDX/NOPB offers native shutdown-default behavior ideal for fail-safe flash systems; versus TPS61310DSKR, it delivers complete flash subsystem integration-reducing component count by ≥4 and eliminating layout-sensitive external FET routing.
Availability
LM3551SDX/NOPB is available at Aetrix Electronics and suitable for smartphone camera flash, digital still camera (DSC) flash, and camcorder torch applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM3551SDX/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, embedded processing, and power management ICs, with leadership in precision analog and high-reliability power solutions.
The LM3551SDX/NOPB belongs to TI's white LED flash driver product line, engineered specifically for mobile imaging systems requiring integrated torch/flash control, robust fault protection, and compact WSON packaging.
FAQ
What is the maximum continuous torch current supported by LM3551SDX/NOPB?
The LM3551SDX/NOPB supports up to 200mA continuous current in Torch mode via the FET-T switch (RDSON = 0.98Ω). This is set by the RT resistor using the equation RTORCH = (1.265V / ITORCH) − 0.98Ω. Exceeding this current risks thermal overload due to FET-T power dissipation; the device does not regulate above 200mA in torch-only operation. LM3551SDX/NOPB maintains this limit across −40°C to +85°C ambient.
How does the flash timeout function work on LM3551SDX/NOPB?
The LM3551SDX/NOPB implements flash timeout by sinking a precise 1.4µA (typ) current from the FTO pin to charge an external capacitor CFTO. When the voltage across CFTO reaches 1.16V (typ), the internal timeout comparator disables both FET-T and FET-F, terminating the flash pulse. The timeout duration is calculated as TFTO = CFTO × (1.16V ÷ 1.4µA). Grounding FTO disables this feature.
Can LM3551SDX/NOPB drive multiple parallel flash LEDs?
Yes, LM3551SDX/NOPB can drive multiple parallel flash LEDs provided total current remains ≤1A and forward voltage stays within the boost converter's capability (up to ~20V output). Each LED string must share a common cathode tied to FET-F/FET-T, and current must be balanced via matched RT/RF sense resistors. Layout must minimize trace inductance to avoid current imbalance during fast flash pulses.
What is the purpose of the VC pin on LM3551SDX/NOPB?
The VC pin on LM3551SDX/NOPB is the compensation node for the internal voltage error amplifier. It connects to an external RC/CC network (e.g., 10kΩ + 4.7nF) to stabilize the feedback loop, counteract the right-half-plane zero inherent in boost converters, and ensure ≥45° phase margin. Proper VC network design prevents oscillation during load transients and maintains regulation accuracy across input voltage and temperature ranges.
Does LM3551SDX/NOPB require external diodes or MOSFETs for basic operation?
No, LM3551SDX/NOPB integrates all critical power elements: the main boost switch (SW FET), torch FET (FET-T), and flash FET (FET-F). Only external passive components are required-inductor, input/output capacitors, current-sense resistors (RT/RF), flash timeout capacitor (CFTO), and soft-start capacitor (CSS). No external diode or MOSFET is needed for standard torch/flash operation per the typical application circuit.
LM3551SDX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 1A (Flash)
- Frequency:
- 1.25MHz
- Dimming:
- -
- Applications:
- Camera Flash
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-WSON (4x4)
LM3551SDX/NOPB FAQ
1.How can I place an order for LM3551SDX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3551SDX/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 LM3551SDX/NOPB reliable?
The price and inventory of LM3551SDX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3551SDX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3551SDX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3551SDX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3551SDX/NOPB?
LM3551SDX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3551SDX/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 LM3551SDX/NOPB?
For technical support, including LM3551SDX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3551SDX/NOPB requirements.
6.How does Aetrix verify that LM3551SDX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3551SDX/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 LM3551SDX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3551SDX/NOPB?
All LM3551SDX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3551SDX/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 LM3551SDX/NOPB part is unused and in its original packaging.
Return procedure for LM3551SDX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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