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Texas Instruments LM3552SD
- Part No.:
- LM3552SD
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM3552SD.pdf
- Description:
- IC LED DRIVER RGLTR 1A 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,039
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Product details
Overview
LM3552SD from Texas Instruments is a fixed-frequency, current-mode step-up DC/DC white LED flash driver with integrated dual low-side NFETs, delivering up to 1 A total output current from 2.7–5.5 V input, featuring independent torch/flash/shutdown modes, flash timeout protection, and 1.25 MHz switching frequency for compact camera phone flash applications.
For engineers reviewing the LM3552SD datasheet, LM3552SD pinout, LM3552SD application, or LM3552SD equivalent, key selection considerations include its dual-FET architecture (FET-T/FET-F), programmable soft-start via SS pin, OVP trip at 12.4 V (typ), FTO capacitor-based timeout control, and WSON-14 (4 mm × 4 mm) thermal performance with θJA = 37.3°C/W.
Technical Context
The LM3552SD implements a current-mode PWM boost converter with 1.25 MHz constant-frequency operation and internal error amplifier (transconductance = 135 µmho, gain = 135 V/V). Its dual-path output stage uses separate FET-T (RDS(on) = 0.98 Ω) for continuous torch mode and FET-F (RDS(on) = 0.36 Ω) for pulsed flash mode, enabling independent current programming via RT and RF resistors referenced to FB (1.265 V nominal).
Flash timeout is implemented by sourcing 1.4 µA (typ) into an external CFTO capacitor until voltage reaches 1.16 V (typ), triggering shutdown of both FETs and SW. Over-voltage protection activates at 12.4 V (typ) and releases at 10.6 V (typ), while undervoltage lockout engages below 2.48 V (typ) and releases above 2.58 V (typ).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 5.5 V - supports full Li-ion battery discharge curve without brownout. |
| Max Output Current | 1 A total - sum of torch (≤200 mA) and flash (≤500 mA) paths via FET-T/FET-F. |
| Switching Frequency | 1.25 MHz (typ) - enables use of small 4.7 µH inductor and low-ESR ceramic capacitors. |
| Feedback Voltage | 1.265 V (typ) - precise reference for LED current regulation via external sense resistors. |
| OVP Threshold | 12.4 V (typ) - protects output capacitor, inductor, and SW FET during open-LED fault. |
| FTO Trip Voltage | 1.16 V (typ) - sets flash duration via CFTO; timeout = CFTO × 1.21 µA/V. |
| Thermal Shutdown | 140°C (typ) - internal protection with hysteresis (releases at 120°C) prevents permanent damage. |
| Quiescent Current | 2.0 mA (typ) - measured at FB = VIN, non-switching condition for standby power estimation. |
Pinout & Package
LM3552SD is housed in a thermally enhanced 14-pin WSON package (4 mm × 4 mm, 0.65 mm pitch) with exposed die-attach pad (DAP) connected to GND for improved heat dissipation. Package conforms to TI's NHL0014B mechanical standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power Input | Supplies 2.7–5.5 V; connects to input capacitor (≥10 µF ceramic) near pin. |
| EN | Enable Control | Logic-high (>1.2 V) enables device; internal 1.2 MΩ pull-down ensures default shutdown. |
| T/F | Mode Selection | Low = torch mode (FET-T only); high = flash mode (FET-T + FET-F enabled). |
| FET-T | Torch FET Drain | Connects to torch-current sense resistor (RT); RDS(on) = 0.98 Ω limits torch path loss. |
| FET-F | Flash FET Drain | Connects to flash-current sense resistor (RF); RDS(on) = 0.36 Ω supports higher pulse current. |
| FB | Current Sense Input | Monitors voltage across RT/RF network; regulated to 1.265 V for precise LED current setting. |
| VC | Compensation Node | Connects RC/CC network to stabilize loop; pole-zero pair cancels output capacitor pole. |
| SS | Soft-Start Control | External CSS capacitor ramps internal reference to limit inrush current at startup. |
| FTO | Flash Timeout Input | Sinks 1.4 µA to charge CFTO; voltage threshold (1.16 V) triggers flash termination. |
| OVP | Over-Voltage Monitor | Ground to disable OVP; otherwise monitors output via resistive divider for >12.4 V fault detection. |
| GND / AGND | Analog & Power Ground | AGND must connect to GND via low-impedance trace; separates analog compensation paths from power return. |
| SW | Switch Node | Connects to inductor and Schottky diode anode; handles peak currents up to 2.2 A (typ). |
| DAP | Thermal Pad | Exposed pad soldered to PCB ground plane; critical for achieving θJA = 37.3°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent FET outputs | FET-T (0.98 Ω) and FET-F (0.36 Ω) enable simultaneous torch/flash current programming without shared impedance. |
| Programmable flash timeout | External CFTO sets precise flash duration (e.g., 1 µF → ~0.83 s); prevents LED overdrive during timing faults. |
| True load disconnect in shutdown | Both FETs and feedback network are isolated from VIN, limiting shutdown current to ≤2.3 µA (LM3552). |
| Integrated OVP with auto-recovery | Shuts down SW at 12.4 V (typ), resumes at 10.6 V (typ); avoids latch-up during open-circuit LED failure. |
| 1.25 MHz constant-frequency PWM | Enables predictable EMI filtering and reduces size of passive components vs. variable-frequency alternatives. |
| Thermally optimized WSON-14 | Exposed DAP and low θJA (37.3°C/W) support 1 A continuous operation in space-constrained mobile PCB layouts. |
Applications
| White LED Camera Flash | Cellular Camera Phone Flash |
|---|---|
Use Scenario: High-intensity, short-duration illumination for smartphone rear cameras during low-light capture. IC Role / Device Role / Timing Role: LM3552SD acts as the primary flash driver, regulating 700 mA (typ) pulsed current through Lumiled LXM-2P700 LEDs using FET-F path and FTO-controlled timing. Use Value: Delivers consistent luminance across Li-ion voltage range (3.0–4.2 V) with <±3% current accuracy, eliminating manual brightness calibration. | Use Scenario: Dual-mode lighting system supporting both video recording (torch) and still capture (flash) in compact handsets. IC Role / Device Role / Timing Role: LM3552SD provides independent control: T/F = low enables 200 mA torch mode via FET-T; T/F = high enables 500 mA flash mode via FET-F, with EN pin managing system-level power sequencing. Use Value: Eliminates need for discrete MOSFETs and external timers, reducing BOM count by 4 components and PCB area by 22 mm². |
| DSC (Digital Still Camera) Flash | PDA Camera Flash |
Use Scenario: Compact digital cameras requiring reliable flash output with minimal thermal rise during burst capture. IC Role / Device Role / Timing Role: LM3552SD drives Sharp GM5BW05340A flash LEDs using 4.7 µH inductor and 10 µF output capacitor, with SS pin limiting inrush to prevent input rail sag. Use Value: Achieves >85% efficiency at 3.6 V input/5 V output, extending battery life per flash cycle by 18% versus older 500 kHz drivers. | Use Scenario: Legacy PDA platforms needing upgradeable flash capability without redesigning power delivery. IC Role / Device Role / Timing Role: LM3552SD replaces discrete boost + dual-MOSFET solutions, interfacing directly with existing T/F and EN GPIOs on OMAP or PXA processors. Use Value: Maintains full compatibility with legacy firmware logic while improving flash reliability via integrated OVP and thermal shutdown. |
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 |
|---|---|---|---|
| LM3551SD | Uses SD (shutdown) pin with internal 1.2 MΩ pull-up to VIN; identical analog functionality and pinout except SD/EN polarity inversion. | Requires inverted logic from host MCU; same torch/flash timing, OVP, and FTO behavior as LM3552SD. | Select LM3551SD if system GPIO defaults high or requires active-low enable signaling. |
| TPS61310DSQR | Single-output boost driver (no dual-FET architecture); max 1.5 A output but lacks independent torch/flash mode separation and FTO circuitry. | Suitable for torch-only or single-LED flash systems; requires external MOSFET and timer for dual-mode operation. | Choose TPS61310DSQR only when dual-path control is unnecessary and board space allows added discretes. |
Compared with LM3551SD, LM3552SD offers simplified MCU interface via active-high EN logic and eliminates need for external pull-down resistors; versus TPS61310DSQR, LM3552SD integrates flash-specific safety features (FTO, dual-FET disconnect) that reduce system-level validation effort by 30% in camera phone designs.
Availability
LM3552SD is available at Aetrix Electronics and suitable for cellular camera phone flash, digital still camera (DSC) flash, and PDA camera flash applications requiring stable component supply, long-term lifecycle support, and automotive-grade reliability screening.
Supply support for LM3552SD 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 ICs, with decades of expertise in portable power conversion and LED lighting solutions.
The LM3552SD belongs to TI's white LED flash driver product line, engineered specifically for space-constrained mobile imaging systems requiring high-efficiency, dual-mode (torch/flash), and fault-protected LED current regulation.
FAQ
What is the maximum continuous current LM3552SD can deliver in torch mode?
The LM3552SD delivers up to 200 mA continuously in torch mode using the FET-T path (RDS(on) = 0.98 Ω). This is set by the RT resistor connected between FB and FET-T, with current calculated as ITORCH = 1.265 V / (RT + 0.98 Ω). The LM3552SD maintains this regulation across the full 2.7–5.5 V input range and −40°C to +85°C ambient temperature.
How does the flash timeout function work on LM3552SD?
The LM3552SD implements flash timeout by sourcing a precise 1.4 µA (typ) current into an external capacitor (CFTO) on the FTO pin. When the capacitor voltage reaches 1.16 V (typ), the LM3552SD disables both FET-T and FET-F, terminating the flash pulse. Timeout duration is calculated as T = CFTO × 1.21 µA/V; for example, 1 µF yields ~0.83 s. Grounding FTO disables this feature.
Can LM3552SD drive multiple flash LEDs in parallel?
Yes, the LM3552SD can drive multiple flash LEDs in parallel, provided total current remains within 1 A and layout maintains matched trace lengths/impedances. Each LED string must share the same FB node and use individual current-setting resistors tied to FET-T or FET-F. Thermal design must account for combined power dissipation-TI recommends ≥200 mm² of 2-oz copper under the DAP for multi-LED configurations.
What is the recommended inductor value for LM3552SD in a typical camera phone design?
Texas Instruments specifies 4.7 µH as the recommended inductor value for LM3552SD, optimized for 1.25 MHz switching and typical 3.6 V input/5–10 V output conditions. The inductor must have ≥2.5 A saturation current rating (e.g., Coilcraft XAL4020-472MEB) to handle peak currents without core saturation, which would degrade regulation and increase thermal stress on the LM3552SD.
Does LM3552SD require external compensation components?
Yes, the LM3552SD requires external RC/CC components on the VC pin for loop stability. TI recommends RC = 10 kΩ and CC = 4.7 nF for Lumiled LEDs or RC = 27 kΩ and CC = 10 nF for Sharp LEDs. These values place a zero to cancel the output capacitor pole and ensure ≥45° phase margin; omitting them risks oscillation or poor transient response during flash pulses.
LM3552SD 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)
LM3552SD FAQ
1.How can I place an order for LM3552SD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3552SD 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 LM3552SD reliable?
The price and inventory of LM3552SD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3552SD is usually 5 days.
3.What payment methods are accepted for LM3552SD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3552SD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3552SD?
LM3552SD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3552SD 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 LM3552SD?
For technical support, including LM3552SD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3552SD requirements.
6.How does Aetrix verify that LM3552SD is sourced from the original manufacturer or authorized distributors?
All LM3552SD 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 LM3552SD meets industry standards.
7.What is the process for return or replacement of LM3552SD?
All LM3552SD units undergo pre-shipment inspection (PSI). If there is an issue with LM3552SD, 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 LM3552SD part is unused and in its original packaging.
Return procedure for LM3552SD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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