Packaging information
| Package | Pins DSBGA (YFF) | 12 |
| Operating temperature range (°C) -40 to 85 |
| Package qty | Carrier 3,000 | LARGE T&R |
Features for the LM3643
- 1.5 A Total Allowed LED Current During Operation
(ILED1 + ILED2 = 1.5 A) - Dual Independent LED Current Source Programmability
- Accurate and Programmable LED Current Range from
1.4 mA to 1.5 A - Optimized Flash LED Current During Low Battery
Conditions (IVFM) - > 85% Efficiency in Torch Mode (@ 100 mA) and
Flash Mode (@1 A to 1.5 A) - Grounded Cathode LED Operation for Improved Thermal
Management - Small Solution Size: < 16 mm2
- Hardware Strobe Enable (STROBE)
- Synchronization Input for RF Power Amplifier Pulse
Events (TX) - Hardware Torch Enable (TORCH/TEMP)
- Remote NTC Monitoring (TORCH/TEMP)
- 400-kHz I2C-Compatible Interface
- LM3643 (I2C Address = 0x63)
- LM3643A (I2C Address = 0x67)
Description for the LM3643
The LM3643 is a dual LED flash driver that provides a high level of adjustability within a small solution size. The LM3643 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the dual 1.5-A constant current LED sources. The total LED current the LM3643 boost can deliver is 1.5 A (ILED1 + ILED2 ). The dual 128 level current sources provide the flexibility to adjust the current ratios between LED1 and LED2 with each driver capable of delivering a maximum of 1.5 A (ex: ILED1 = 1.5 A and ILED2 = 0FF, ILED1 = 0FF and ILED2 = 1.5 A, or a current configuration with a current less than 1.5 A , ILED1 = 950 mA and ILED2 = 250 mA). An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.
Features of the LM3643 are controlled via an I2C-compatible interface. These features include: hardware flash and hardware torch pins (STROBE and TORCH/TEMP), a TX interrupt, and an NTC thermistor monitor. The device offers independently programmable currents in each output leg to drive the LEDs in a Flash or Movie Mode (Torch) condition.
The 2-MHz or 4-MHz switching frequency options, overvoltage protection (OVP), and adjustable current limit allow for the use of tiny, low-profile inductors and (10-µF) ceramic capacitors. The device operates over a –40°C to 85°C ambient temperature range.