AS3649 Datasheet, PDF (1/39 Pages) ams AG – 2500mA High Current LED Flash Driver

AS3649
2500mA High Current LED Flash Driver
1 General Description
The AS3649 is an inductive high efficient DCDC step up converter
with two current sources. The DCDC step up converter operates at a
fixed frequency of 4MHz and includes soft startup to allow easy
integration into noise sensitive RF systems. The two current sources
can operate in flash / torch or video light modes.
The AS3649 includes flash timeout, overvoltage, overtemperature,
undervoltage and LED short/open circuit protection functions. A
TXMASK/TORCH function reduces the flash current in case of
parallel operation to the RF power amplifier and avoids a system
shutdown. Alternatively this pin can be used to directly operate the
torch light directly. If the TXMask function is not used, it can be used
as a hardware torch input (programmable).
A hardware NTC pin can be used to measure the LED temperature
with the ADC and to automatically reduce the LED current if a
temperature threshold is exceeded.
The AS3649 is controlled by an I²C interface and has a hardware
reset pin ON. Setting ON=0 resets the AS3649. Interface input
voltage levels are 1.8V compliant.
The AS3649 is available in a space-saving WL-CSP package
measuring only 2.06x2.02x0.6mm and operates over the -30ºC to
+85ºC temperature range.
Figure 1. Typical Operating Circuit
2 Key Features
High efficiency 4MHz fixed frequency DCDC Boost converter
with soft start allows small coils
- Stable even in coil current limit
LED current adjustable up to 2x1000mA(2x1250mA with current
boost) or 2000mA and automatic load balancing for two LEDs
Automatic current adjustment for low battery voltage
PWM operation for lower output current for reliable light output
of the LED; can run at 31.5kHz to avoid audible noise
Protection functions:
Automatic Flash Timeout timer to protect the LED(s)
Overvoltage and undervoltage Protection
Overtemperature Protection
LED short/open circuit protection
ADC to measure LED temperature
NTC to automatically reduce the flash current if the LED
temperature is too high (programmable level)
I²C Interface with hardware reset pin
Available in tiny WL-CSP Package, 16 balls 0.5mm pitch,
2.06x2.02x0.6mm package size
3 Applications
Flash/Torch for mobile phones
 
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