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Texas Instruments LM3552SDX
- Part No.:
- LM3552SDX
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM3552SDX.pdf
- Description:
- IC LED DRIVER RGLTR 1A 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,969
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Product details
Overview
LM3552SDX from Texas Instruments is a fixed-frequency, current-mode step-up DC/DC white LED flash driver with dual integrated low-side NFETs (FET-T and FET-F), 1.25MHz switching frequency, 2.7–5.5V input range, and up to 1A total drive current for high-power camera flash applications in mobile devices.
For engineers reviewing the LM3552SDX datasheet, LM3552SDX pinout, LM3552SDX application, or LM3552SDX equivalent, key selection considerations include torch/flash mode control via T/F pin, programmable flash timeout via external CFTO, independent soft-start (SS) and over-voltage protection (OVP), and WSON-14 package thermal performance with θJA = 37.3°C/W.
Technical Context
The LM3552SDX implements a current-mode PWM boost converter architecture with 1.25MHz constant switching frequency and internal error amplifier (gm = 135 µmho, AV = 135 V/V). It uses two dedicated low-side NFETs-FET-T (RDSON = 0.98Ω, 200mA max) for continuous torch mode and FET-F (RDSON = 0.36Ω, 500mA max) enabled only in flash mode-to deliver combined output currents up to 1A.
Flash timeout protection operates via an internal 1.4µA current source charging external capacitor CFTO; trip occurs at VFTO = 1.16V, enabling precise pulse duration control. Over-voltage protection engages at 12.4V (typ.) and releases at 10.6V (typ.), while under-voltage lockout activates at 2.48V (typ.) and releases at 2.58V (typ.).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 5.5V - supports full Li-ion battery discharge curve without regulation loss. |
| Switching Frequency | 1.25MHz (typ.) - enables use of small 4.7µH inductors and low-ESR ceramic capacitors. | Max Output Current | 1A total - sum of torch (via FET-T) and flash (via FET-T + FET-F) path currents. |
| Feedback Voltage | 1.265V (typ.) - tightly regulated reference for accurate LED current setting via RT/RF resistors. |
| OVP Threshold | 12.4V (typ.) - protects output capacitor, inductor, and SW FET during open-LED or FB short failures. |
| Thermal Shutdown | 140°C (typ.) - internal protection with hysteresis (releases at 120°C) prevents permanent junction damage. |
| Package | 14-pin WSON (4mm × 4mm, non-pullback) - low-profile, thermally enhanced die-attach pad (DAP) for PCB heat sinking. |
Pinout & Package
The LM3552SDX is housed in a 14-pin WSON package (TI package code NHL0014B) with exposed die-attach pad (DAP) connected to GND for thermal dissipation. Pin 1–14 are arranged in a 3×5 grid with DAP centered on bottom side.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 9) | Power Input | Accepts 2.7–5.5V supply; connects to input capacitor and battery rail. |
| EN (Pin 5) | Enable Control | Active-high logic input; internal 1.2MΩ pull-down ensures shutdown when unconnected. |
| T/F (Pin 13) | Mode Selection | Logic level determines operation: low = torch mode (FET-T only), high = flash mode (FET-T + FET-F). |
| SW (Pin 8) | Switch Node | Drives external boost inductor; voltage swings up to 20V (max); requires low-ESR Schottky catch diode. |
| FET-T (Pin 14) | Torch FET Drain | Output node for continuous torch current path; RDSON = 0.98Ω limits power loss at ≤200mA. |
| FET-F (Pin 2) | Flash FET Drain | Output node enabled only in flash mode; RDSON = 0.36Ω supports higher pulsed current (≤500mA). |
| FB (Pin 4) | Current Sense Feedback | Monitors voltage drop across RT/RF to regulate LED current; reference = 1.265V. |
| VC (Pin 3) | Compensation | Connects RC/CC network to stabilize loop; pole-zero pair cancels output capacitor pole. |
| FTO (Pin 12) | Flash Timeout | Sinks 1.4µA to charge external CFTO; voltage threshold = 1.16V triggers automatic shutdown. |
| SS (Pin 11) | Soft-Start | Charges external CSS to ramp internal reference; controls inrush current during startup. |
| OVP (Pin 10) | Over-Voltage Monitor | Ground to disable OVP; otherwise monitors FB node and shuts down SW if >12.4V detected. |
| GND / AGND (Pins 1,7,DAP) | Analog & Power Ground | DAP must be soldered to large copper pour; AGND ties compensation components to minimize noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-path LED current control | Independent torch (FET-T only) and flash (FET-T + FET-F) modes enable optimized efficiency and thermal management per use case. |
| Programmable flash timeout | External CFTO sets precise flash pulse duration (e.g., 1µF → ~830ms); prevents LED overstress during timing faults. |
| True load disconnect in shutdown | Both FETs and feedback network are isolated from VIN/GND, limiting shutdown current to ≤2.3µA (LM3552). |
| Integrated OVP with auto-recovery | Clamps output at 12.4V and cycles SW on/off until fault clears - avoids catastrophic capacitor failure without manual reset. |
| 1.25MHz constant-frequency PWM | Enables predictable EMI filtering and consistent transient response across input voltage and load conditions. |
Applications
| White LED Camera Flash | Cellular Camera Phone Flash |
|---|---|
Use Scenario: High-intensity, short-duration illumination for smartphone rear/front cameras during low-light capture. IC Role / Device Role / Timing Role: LM3552SDX acts as the primary flash driver, delivering up to 1A pulsed current to LUMILEDS LXCL-PWF1 or Sharp GM5BW05340A LEDs in flash mode. Use Value: Dual-FET architecture enables peak brightness without thermal throttling; flash timeout prevents LED degradation from extended pulses. | Use Scenario: Compact, battery-efficient flash solution integrated into thin mobile phone PCBs with tight layout constraints. IC Role / Device Role / Timing Role: LM3552SDX provides torch mode (≤200mA) for video lighting and flash mode (≤1A) for still capture, controlled by baseband processor GPIOs. Use Value: WSON-14 package (4mm × 4mm) minimizes board area; 1.25MHz switching allows tiny 4.7µH inductor and 10µF MLCCs. |
| DSC (Digital Still Camera) Flash | Camcorder Torch (Flashlight) Lamp |
Use Scenario: Portable digital cameras requiring reliable, repeatable flash bursts with consistent color temperature and intensity. IC Role / Device Role / Timing Role: LM3552SDX regulates LED current via precision FB voltage (1.265V ± 2.5mV), ensuring stable luminance across battery voltage decay. Use Value: Tight feedback tolerance and current-mode control maintain ±5% LED current accuracy from 2.7V to 5.5V input. | Use Scenario: Continuous illumination for camcorders or action cameras during video recording in dim environments. IC Role / Device Role / Timing Role: LM3552SDX operates in torch mode using only FET-T, delivering regulated 200mA at <0.2W dissipation for sustained runtime. Use Value: Low RDSON-T (0.98Ω) and true load disconnect in shutdown extend battery life; SS pin enables smooth brightness ramp-up. |
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 |
|---|---|---|---|
| LM3551SDX | Uses SD (shutdown) pin instead of EN; internal 1.2MΩ pull-up to VIN vs. LM3552's 1.2MΩ pull-down to GND. | Requires active-low enable signal; incompatible with systems designed for active-high EN control. | Select LM3551SDX only if host MCU GPIO is open-drain or actively drives low during sleep. |
| TPS61310DSQR | Single-FET boost driver (no dual-path torch/flash); max 1.5A switch current but no integrated FET-T/FET-F separation. | Lacks hardware torch/flash mode distinction; requires external logic or firmware to emulate dual-mode behavior. | Choose TPS61310DSQR when system-level control flexibility outweighs need for integrated mode separation and flash timeout. |
Compared with LM3551SDX, the LM3552SDX offers simplified active-high enable interface and identical analog functionality; versus TPS61310DSQR, it delivers hardware-enforced dual-mode operation and built-in flash safety features at the cost of less general-purpose boost capability.
Availability
LM3552SDX is available at Aetrix Electronics and suitable for cellular camera phone flash, digital still camera (DSC) flash, and camcorder torch applications requiring stable component supply, long-term lifecycle support, and automotive-grade reliability screening.
Supply support for LM3552SDX 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 driver innovation.
The LM3552SDX belongs to TI's white LED flash driver product line, engineered specifically for space-constrained, battery-powered imaging systems where precise current control, thermal safety, and dual-mode flexibility are critical.
FAQ
What is the maximum continuous current the LM3552SDX can deliver in torch mode?
The LM3552SDX delivers up to 200mA continuously in torch mode using only the FET-T path. This is limited by the 0.98Ω RDSON-T and thermal design margin; exceeding this current risks thermal shutdown or reduced lifetime. The LM3552SDX torch mode does not engage FET-F, preserving efficiency and minimizing junction temperature rise during extended video lighting.
How does the LM3552SDX implement flash timeout protection, and what capacitor value yields a 500ms timeout?
The LM3552SDX sources a precise 1.4µA current into the external CFTO capacitor on the FTO pin; timeout triggers when voltage reaches 1.16V. Using CFTO = TFTO × 1.21 µA/V, a 500ms timeout requires CFTO ≈ 0.605µF - a standard 0.68µF X7R ceramic capacitor is recommended. The LM3552SDX ignores FTO if grounded, disabling timeout entirely.
Can the LM3552SDX drive multiple white LEDs in series, and what is the maximum output voltage?
Yes - the LM3552SDX boost topology supports series-connected white LEDs; its OVP threshold is 12.4V (typ.), and SW pin withstands up to 20V. With typical forward voltages of 3.0–3.6V per LED, the LM3552SDX can reliably drive up to three LEDs in series (≤10.8V VF) while maintaining regulation and safety margins. Exceeding 12.4V output risks OVP activation.
What is the role of the VC pin on the LM3552SDX, and how is compensation configured?
The VC pin on the LM3552SDX is the error amplifier output used for loop compensation. A series RC/CC network (e.g., 10kΩ/4.7nF) connects between VC and GND to place a dominant pole-zero pair that cancels the output capacitor's ESR zero and stabilizes the current-mode boost loop. Proper VC network selection ensures ≥45° phase margin and robust transient response across all operating conditions for the LM3552SDX.
Does the LM3552SDX require external diodes or MOSFETs beyond the integrated FET-T and FET-F?
No - the LM3552SDX integrates both low-side FETs (FET-T and FET-F) and the error amplifier, PWM controller, and protection circuits. However, an external Schottky catch diode (e.g., 20V/1A) is mandatory between SW and output, and external inductor (4.7µH), input/output capacitors (10µF MLCC), and current-setting resistors (RT/RF) are required. No external high-side or synchronous rectifier MOSFETs are needed for basic operation of the LM3552SDX.
LM3552SDX 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)
LM3552SDX FAQ
1.How can I place an order for LM3552SDX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3552SDX 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 LM3552SDX reliable?
The price and inventory of LM3552SDX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3552SDX is usually 5 days.
3.What payment methods are accepted for LM3552SDX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3552SDX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3552SDX?
LM3552SDX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3552SDX 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 LM3552SDX?
For technical support, including LM3552SDX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3552SDX requirements.
6.How does Aetrix verify that LM3552SDX is sourced from the original manufacturer or authorized distributors?
All LM3552SDX 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 LM3552SDX meets industry standards.
7.What is the process for return or replacement of LM3552SDX?
All LM3552SDX units undergo pre-shipment inspection (PSI). If there is an issue with LM3552SDX, 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 LM3552SDX part is unused and in its original packaging.
Return procedure for LM3552SDX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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