The LM3648 is an LED flash driver that provides a high level of adjustability within a small solution size. The LM3648 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the 1.5-A constant current LED source. An adaptive regulation method ensures the current source remains in regulation and maximizes efficiency.
Features of the LM3648 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 64 programmable currents in Flash and 128 levels in 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.
PART NUMBER | PACKAGE | BODY SIZE (MAX) |
---|---|---|
LM3648 | DSBGA (12) | 1.69 mm × 1.31 mm |
Changes from C Revision (September 2016) to D Revision
Changes from B Revision (September 2015) to C Revision
Changes from A Revision (August 2015) to B Revision
Changes from * Revision (October 2014) to A Revision
PIN | TYPE(1) | DESCRIPTION | ||
---|---|---|---|---|
NUMBER | NAME | |||
A1 | GND | G | Ground | |
A2 | IN | P | Input voltage connection. Connect IN to the input supply and bypass to GND with a 10-µF or larger ceramic capacitor. | |
A3 | SDA | I/O | Serial data input/output in the I2C Mode on LM3648. | |
B1 | SW | P | Drain connection for Internal NMOS and synchronous PMOS Switches. | |
B2 | STROBE | I | Active high hardware flash enable. Drive STROBE high to turn on Flash pulse. Internal pulldown resistor of 300 kΩ between STROBE and GND. | |
B3 | SCL | I | Serial clock input for LM3648. | |
C1 | OUT | P | Step-up DC-DC converter output. Connect a 10-µF ceramic capacitor between this terminal and GND. | |
C2 | HWEN | I | Active high enable pin. High = Standby, Low = Shutdown/Reset. Internal pulldown resistor of 300 kΩ between HWEN and GND. | |
C3 | TORCH/TEMP | I/P | Torch terminal input or threshold detector for NTC temperature sensing and current scale back. | |
D1 | LED | P | High-side current source output for flash LED. Connect pin D1 to D3 externally. | |
D2 | TX | I | Configurable dual polarity power amplifier synchronization input. Internal pulldown resistor of 300 kΩ between TX and GND. | |
D3 | LED | P | High-side current source output for flash LED. Connect pin D1 to D3 externally. |
MIN | MAX | UNIT | ||
---|---|---|---|---|
IN, SW, OUT, LED | −0.3 | 6 | V | |
SDA, SCL, TX, TORCH/TEMP, HWEN, STROBE | −0.3 | (VIN+ 0.3) w/ 6 V max | ||
Continuous power dissipation(3) | Internally limited | |||
Junction temperature (TJ-MAX) | 150 | °C | ||
Maximum lead temperature (soldering) | See(4) | |||
Storage temperature, Tstg | −65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | ±2500 | V |
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) | ±150 |
MIN | MAX | UNIT | ||
---|---|---|---|---|
VIN | 2.5 | 5.5 | V | |
Junction temperature (TJ) | −40 | 125 | °C | |
Ambient temperature (TA) (3) | −40 | 85 | °C |
THERMAL METRIC(1) | LM3648 | UNIT | |
---|---|---|---|
YFF (DSBGA) | |||
12 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 90.2 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 0.5 | °C/W |
RθJB | Junction-to-board thermal resistance | 40.0 | °C/W |
ΨJT | Junction-to-top characterization parameter | 3.0 | °C/W |
ΨJB | Junction-to-board characterization parameter | 39.2 | °C/W |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
ƒSW | Switching frequency | 2.5 V ≤ VIN ≤ 5.5 V | –6% | 4 | 6% | MHz |
LM3648TT | ||
ƒSW = 2 MHz | Flash | |
Brightness Code = 0x3F |
ƒSW = 4 MHz | Flash | |
Brightness Code = 0x3F |
ƒSW = 2 MHz | Torch | |
Brightness Code = 0x7F |
ƒSW = 4 MHz | Torch | |
Brightness Code = 0x7F |
HWEN = 0 V | I2C = 0 V | |
HWEN = 1.8 V | I2C = 0 V | |
ƒSW = 2 MHz | Flash | VLED = 4.5 V |
Brightness Code = 0x3F | ICL = 1.9 A |
ƒSW = 2 MHz | Flash | VLED = 4.5 V |
Brightness Code = 0x3F | ICL = 2.8 A |
ƒSW = 2 MHz | Flash | |
Brightness Code = 0x2B |
LM3648TT | ƒSW = 2 MHz | Torch |
Brightness Code = 0x59 |
LM3648TT | ƒSW = 4 MHz | Torch |
Brightness Code = 0x59 |
HWEN = VIN | I2C = VIN | |
HWEN = 1.8 V | I2C = 1.8 V | |
ƒSW = 4 MHz | Flash | VLED = 4.5 V |
Brightness Code = 0x3F | ICL = 1.9 A |
ƒSW = 4 MHz | Flash | VLED = 4.5 V |
Brightness Code = 0x3F | ICL = 2.8 A |