austriamicrosystems AG is now ams AG The technical content of this austriamicrosystems datasheet is still valid. Contact information: Headquarters: ams AG Tobelbaderstrasse 30 8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 e-Mail: ams sales ams.com Please visit our website at www.ams.com Datasheet AS3490 Highly Efficient 2-6 LEDs Backlight Driver with PWM Input 1 General Description 2 Key Features 2 MHz DCDC Boost converter The AS3490 is an inductive highly efficient DCDC boost converter. The DCDC converter operates at a fixed fre- - Small 4.7H external coil quency of 2MHz and includes soft startup to allow easy - Very high system efficiency of 86% (DCDC and integration into noise sensitive RF systems. A predict- current sources combined) able startup is guaranteed even with very low duty cycle - Very low voltage changes on output to avoid PWM input signals. The voltage on the output capacitor acoustic noise on output capacitor even with PWM is controlled to minimize ripple and to avoid any acoustic - Smooth startup even under low duty cycle PWM effects for low frequency PWM input signals. conditions The output of the DCDC converter is used for five cur- Three Current sources up to 25mA rent sources connected to up to 6 LEDs. If a current - Low voltage compliance (150mV) source is not required, it shall be connected to VOUT or - High side current source to simplify layout and GND - the AS3490 detects this condition and disables thermal management of the LEDs this current source automatically this keeps the effi- - Automatically detect and disable failing or not used ciency of the system constantly high. LEDs to keep efficiency high The AS3490 is controlled by one enable input, ON. This - Current matching <4% input can also be used to connect a PWM input (like - Current accuracy <7.5% DLS or DBC). Excellent LED current output ripple <500A The AS3490 includes several protection functions like Support DLS (Dynamic Luminance Scaling or DBC) undervoltage lockout, overcurrent and overtemperature. Undervoltage lockout and overcurrent protection No microvias are required to assemble the AS3490. Overtemperature protection Available in a tiny WL-CSP package The AS3490 is available in a space-saving WL-CSP - 3x4 balls, 0.4mm pitch, 1.7x1.4x0.5mm package measuring only 1.7x1.4x0.5mm and operates over the -30C to +85C temperature range. 3 Applications Figure 1. AS3490 Typical Operating Circuit Display backlight driver for mobile phones, digital cam- eras, PND and PMPs. AS3490 www.austriamicrosystems.com/AS3490 1.2 1 - 18 (ptr) ams AG Technical content still valid