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Texas Instruments LM3643AYFFR
- Part No.:
- LM3643AYFFR
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 12-UFBGA, DSBGA
- Datasheet:
-
LM3643AYFFR.pdf
- Description:
- IC LED DRV RGLTR I2C 12DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:2,241
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Product details
Overview
LM3643AYFFR from Texas Instruments is a synchronous boost dual LED flash driver IC with two independent 1.5-A high-side current sources, 4-MHz switching frequency, I²C-compatible interface (address 0x67), and hardware strobe/torch enable-designed for smartphone camera flash applications requiring precise dual-LED current control under varying battery voltage.
For engineers reviewing the LM3643AYFFR datasheet, LM3643AYFFR pinout, LM3643AYFFR application, or LM3643AYFFR equivalent, key selection considerations include its 2.5–5.5 V input range, adaptive IVFM low-battery current scaling, NTC-based thermal monitoring via TORCH/TEMP, and TX-synchronized flash current reduction during RF power amplifier events.
Technical Context
The LM3643AYFFR integrates a fixed-frequency (2 MHz or 4 MHz selectable) current-mode synchronous boost converter with dual high-side current sources, each programmable across 128 levels (flash: 10.9 mA–1.5 A; torch: 0.977 mA–179 mA). Its adaptive regulation maintains ≥158 mV headroom (VHR) across LED1/LED2 to ensure current source compliance.
Hardware control pins-STROBE (flash trigger), TORCH/TEMP (torch enable or NTC thermistor input), and TX (RF PA sync interrupt)-feature internal 300 kΩ pulldowns. The device enters pass mode when VIN ≥ VLED + VHR, eliminating switching loss; otherwise it operates in boost mode with peak current limiting (1.9 A or 2.8 A configurable).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5 V to 5.5 V - supports single-cell Li-ion/Li-poly battery operation without external LDO. |
| Max Total LED Current | 1.5 A (ILED1 + ILED2) - enables high-intensity dual-LED flash while maintaining thermal safety. |
| Switching Frequency | 4 MHz (typ.) - allows use of ultra-small 1 µH inductors and 10 µF ceramic capacitors for <16 mm² solution size. |
| I²C Address | 0x67 - distinct from LM3643 (0x63), enabling coexistence on same bus with both variants. |
| Current Accuracy | ±7% (flash), ±10% (torch) - ensures consistent brightness across temperature (−40°C to +125°C junction). |
| Thermal Shutdown | 150°C (engage), 135°C (release) - protects against sustained overloads in compact mobile enclosures. |
| Quiescent Current | 0.75 mA (active), 10 µA (standby), 0.4 µA (shutdown) - minimizes battery drain during idle states. |
Pinout & Package
LM3643AYFFR uses a 12-pin DSBGA package (1.69 mm × 1.31 mm, 0.4 mm pitch) optimized for space-constrained mobile camera modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (A1) | Ground reference | Primary return path for all currents; must be low-impedance connection to PCB ground plane. |
| IN (A2) | Input supply | Connects to battery rail; requires ≥10 µF ceramic bypass capacitor to suppress ripple and support transient load demands. |
| SDA (A3) | I²C data line | Open-drain bidirectional interface; requires external pull-up to VIN or IOVDD (1.8 V/3.3 V). |
| SW (B1) | Internal switch node | Connects to inductor; high dv/dt node-requires tight layout and minimal trace length to reduce EMI. |
| STROBE (B2) | Hardware flash trigger | Active-high signal; internal 300 kΩ pulldown ensures safe default-off state during boot or reset. |
| SCL (B3) | I²C clock line | Open-drain input; timing compliant with 400 kHz standard mode (t1 = 2.4 µs min clock period). |
| OUT (C1) | Boost output | Drives LED anodes; connects to 10 µF output capacitor and LED cathodes via high-side current sources. |
| HWEN (C2) | Hardware enable/reset | Active-low; pulling low resets registers and forces shutdown; internal 300 kΩ pulldown prevents floating. |
| TORCH/TEMP (C3) | Torch enable or NTC input | Configurable: logic input for torch mode or analog input for thermistor-based current derating below threshold. |
| LED2 (D1) | High-side flash current source | Sinks current from LED2 anode to OUT; grounded-cathode topology improves thermal dissipation in camera module. |
| TX (D2) | RF PA sync interrupt | Active-high input; triggers immediate flash-to-torch current reduction during transmit bursts to limit peak battery current. |
| LED1 (D3) | High-side flash current source | Independent of LED2; enables asymmetric current allocation (e.g., 950 mA + 250 mA) for dual-LED color balancing. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 128-level current programming | Enables precise, asymmetric brightness control for white + amber LED pairs in smartphone dual-flash systems. |
| Adaptive Input Voltage Flash Monitor (IVFM) | Adjusts flash current in real time when VIN drops below user-configurable threshold (2.9–3.6 V), preventing brownout-induced system instability. |
| Hardware strobe + torch enable with internal pulldowns | Eliminates need for external pull-down resistors-reducing BOM count and PCB area in space-critical camera flex circuits. |
| Pass mode operation at high VIN | Disables switching when VIN ≥ VLED + VHR (≥158 mV), achieving >85% efficiency in torch mode and reducing EMI/noise in always-on video recording. |
| NTC thermistor monitoring via TORCH/TEMP pin | Allows closed-loop thermal derating of LED current based on actual module temperature-not ambient-improving reliability in sealed enclosures. |
Applications
| Smartphone Dual-LED Flash | Tablet Camera Module |
|---|---|
Use Scenario: Front/rear camera flash in Android/iOS smartphones with white+amber LED configuration. IC Role / Device Role / Timing Role: Dual high-side current source driving two LEDs independently with synchronized ramp-up and IVFM-based low-battery compensation. Use Value: Delivers consistent color rendering and brightness across battery discharge cycle while meeting JEDEC thermal limits. | Use Scenario: High-resolution rear camera flash in 10-inch tablets with constrained board area near lens assembly. IC Role / Device Role / Timing Role: Compact synchronous boost driver delivering 1.5 A total current in <16 mm² footprint with hardware-triggered strobe timing. Use Value: Enables thin mechanical design without sacrificing flash intensity; pass mode extends battery life during video torch usage. |
| Automotive Interior Camera | Industrial Barcode Scanner |
Use Scenario: Driver-facing cabin camera requiring reliable flash illumination under wide temperature (−40°C to +85°C) and vibration conditions. IC Role / Device Role / Timing Role: Flash driver with NTC-based thermal foldback and TX-synchronized current reduction during cellular/V2X transmit bursts. Use Value: Prevents thermal runaway in sealed automotive housings and avoids interference with critical wireless comms subsystems. | Use Scenario: Handheld barcode scanner needing instant-on flash pulse with minimal latency between trigger and full illumination. IC Role / Device Role / Timing Role: IR Mode-capable driver using STROBE for level-sensitive, externally timed LED pulses without internal ramp delay. Use Value: Achieves sub-millisecond flash activation for rapid scan cycles-critical for high-throughput logistics scanning. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-LED flash driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3643YFFR | I²C address 0x63 (vs. 0x67); identical electrical specs, pinout, and firmware register map. | No functional difference-used when multiple LM3643 variants share same I²C bus without address conflict. | Select LM3643YFFR only if bus addressing requires 0x63; otherwise LM3643AYFFR is drop-in compatible. |
| RT8547GQW | Single 2-A current source (not dual); no IVFM, NTC, or TX sync; 1.2 MHz switching; QFN-16 package (3 mm × 3 mm). | Limited to mono-LED flash; lacks thermal/battery-aware features needed for premium smartphone dual-LED systems. | Choose RT8547GQW only for cost-sensitive, single-LED applications where advanced regulation is unnecessary. |
Compared with LM3643YFFR, LM3643AYFFR offers identical performance with differentiated I²C addressing-enabling multi-device configurations. Versus RT8547GQW, LM3643AYFFR provides true dual-current-source flexibility, adaptive low-VIN operation, and integrated thermal management essential for modern mobile imaging.
Availability
LM3643AYFFR is available at Aetrix Electronics and suitable for smartphone camera modules, tablet imaging subsystems, and automotive interior vision systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM3643AYFFR 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 for industrial, automotive, and consumer applications.
The LM3643 family is designed specifically for high-efficiency, space-constrained mobile camera flash systems-delivering dual-LED current control, intelligent battery-aware regulation, and hardware-synchronized operation in wafer-level chip-scale packaging.
FAQ
What is the I²C address of the LM3643AYFFR and how does it differ from the LM3643YFFR?
The LM3643AYFFR has a fixed I²C address of 0x67, while the LM3643YFFR uses 0x63. This deliberate address separation allows both variants to coexist on the same I²C bus without conflict-enabling flexible system designs where multiple flash drivers are required. All other electrical, timing, and register behaviors of LM3643AYFFR remain identical to LM3643YFFR, making them functionally interchangeable except for address assignment.
How does the Input Voltage Flash Monitor (IVFM) function in the LM3643AYFFR?
The IVFM in LM3643AYFFR dynamically adjusts flash current when input voltage drops below a user-configurable threshold (2.9 V to 3.6 V). It operates in three modes: Stop and Hold (halts ramp-up), Adjust Down Only (reduces current during flash), or Up/Down (adds hysteresis for recovery). This prevents system brownout during high-current flash events and ensures stable operation across the full battery discharge curve-critical for maintaining image quality in smartphones.
Can the LM3643AYFFR drive LEDs with different forward voltages simultaneously?
Yes. The LM3643AYFFR's dual high-side current sources operate independently, each maintaining regulation as long as the required headroom voltage (VHR ≥158 mV) is met between OUT and the respective LED anode. Because OUT is shared, the maximum forward voltage sum is constrained by the boost converter's capability-but typical white+amber LED pairs (e.g., 3.2 V + 2.8 V = 6.0 V) are supported with appropriate inductor and capacitor selection per the LM3643AYFFR datasheet guidelines.
What is the role of the TX pin on the LM3643AYFFR and how is it used in practice?
The TX pin on LM3643AYFFR is a hardware synchronization input that reduces flash current to the programmed torch level when pulled high during a flash event-minimizing peak battery current during concurrent RF power amplifier transmission. When TX returns low, flash current resumes. This feature prevents voltage droop and interference in cellular/Wi-Fi modules, and is implemented without software intervention, ensuring deterministic timing critical for carrier-certified mobile devices.
Does the LM3643AYFFR support thermal protection using an external NTC thermistor?
Yes. The TORCH/TEMP pin on LM3643AYFFR serves dual purpose: as a logic input for torch enable or as an analog input for NTC thermistor monitoring. When configured for NTC mode, the internal 50 µA current source (INTC) biases the thermistor, and the comparator trips at a user-programmable threshold (VTRIP = 0.6 V typ.). Upon trip, LM3643AYFFR scales back LED current to prevent overheating-enabling closed-loop thermal management directly tied to LED module temperature rather than ambient.
LM3643AYFFR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 12-UFBGA, DSBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 2
- Voltage - Supply (Min):
- 2.5V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 1.9A (Switch)
- Frequency:
- 4MHz
- Dimming:
- I2C
- Applications:
- Camera Flash
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DSBGA
LM3643AYFFR FAQ
1.How can I place an order for LM3643AYFFR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3643AYFFR 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 LM3643AYFFR reliable?
The price and inventory of LM3643AYFFR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3643AYFFR is usually 5 days.
3.What payment methods are accepted for LM3643AYFFR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3643AYFFR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3643AYFFR?
LM3643AYFFR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3643AYFFR 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 LM3643AYFFR?
For technical support, including LM3643AYFFR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3643AYFFR requirements.
6.How does Aetrix verify that LM3643AYFFR is sourced from the original manufacturer or authorized distributors?
All LM3643AYFFR 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 LM3643AYFFR meets industry standards.
7.What is the process for return or replacement of LM3643AYFFR?
All LM3643AYFFR units undergo pre-shipment inspection (PSI). If there is an issue with LM3643AYFFR, 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 LM3643AYFFR part is unused and in its original packaging.
Return procedure for LM3643AYFFR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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