AS3649-ZWLT ams

AS3649 2500mA High Current LED Flash Driver 1 General Description 2 Key Features High efficiency 4MHz fixed frequency DCDC Boost converter The AS3649 is an inductive high efficient DCDC step up converter with soft start allows small coils with two current sources. The DCDC step up converter operates at a fixed frequency of 4MHz and includes soft startup to allow easy - Stable even in coil current limit integration into noise sensitive RF systems. The two current sources LED current adjustable up to 2x1000mA(2x1250mA with current can operate in flash / torch or video light modes. boost) or 2000mA and automatic load balancing for two LEDs The AS3649 includes flash timeout, overvoltage, overtemperature, Automatic current adjustment for low battery voltage undervoltage and LED short/open circuit protection functions. A PWM operation for lower output current for reliable light output TXMASK/TORCH function reduces the flash current in case of of the LED can run at 31.5kHz to avoid audible noise parallel operation to the RF power amplifier and avoids a system shutdown. Alternatively this pin can be used to directly operate the Protection functions: torch light directly. If the TXMask function is not used, it can be used Automatic Flash Timeout timer to protect the LED(s) as a hardware torch input (programmable). Overvoltage and undervoltage Protection Overtemperature Protection A hardware NTC pin can be used to measure the LED temperature LED short/open circuit protection with the ADC and to automatically reduce the LED current if a temperature threshold is exceeded. ADC to measure LED temperature 2 NTC to automatically reduce the flash current if the LED The AS3649 is controlled by an I C interface and has a hardware temperature is too high (programmable level) reset pin ON. Setting ON=0 resets the AS3649. Interface input 2 voltage levels are 1.8V compliant. I C Interface with hardware reset pin The AS3649 is available in a space-saving WL-CSP package Available in tiny WL-CSP Package, 16 balls 0.5mm pitch, measuring only 2.06x2.02x0.6mm and operates over the -30C to 2.06x2.02x0.6mm package size +85C temperature range. 3 Applications Flash/Torch for mobile phones Figure 1. Typical Operating Circuit %& ( & & ,+ - )* + ( / . + ( 01 %%% &%%% AS3649 .* * www.ams.com/AS3649 1.0-2 1 - 39 AS3649 Datasheet - Pin Assignments 4 Pin Assignments Figure 2. Pin Assignments (Top View) AS3649 4.1 Pin Description Table 1. Pin Description for AS3649 1 Pin Name Description Pin Number A1 PGND2 Power ground make a short connection between all GND balls Power ground make a short connection between all GND balls A2 PGND1 Positive supply voltage input - connect to supply and make a short connection to input capacitor A3 VIN CVIN and to coil LDCDC Hardware reset input an active low signal resets the registers of AS3649 and enters shutdown A4 ON 2 (and I C lines SDA and SCL are in high-Z), active high allows to operate the device DCDC converter switching node - make a short connection to SW1 / coil LDCDC B1 SW2 DCDC converter switching node - make a short connection to SW2 / coil LDCDC B2 SW1 LED temperature sensor input (NTC) for LED overtemperature protection B3 NTC Function 1: Connect to RF power amplifier enable signal - reduces currents during flash to avoid a system shutdown due to parallel operation of the RF PA and the flash driver B4 TXMASK/TORCH 2 Function 2: Operate torch current level without using the I C interface to operate the torch 2 without need to start a camera processor (if the I C is connected to the camera processor DCDC converter output capacitor - make a short connection to CVOUT / VOUT1 C1 VOUT2 DCDC converter output capacitor - make a short connection to CVOUT / VOUT2 C2 VOUT1 www.ams.com/AS3649 1.0-2 2 - 39