AS3490

Highly Efficient 2-6 LEDs Backlight Driver with PWM Input

www.austriamicrosystems.com/AS3490

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Datasheet

1 General Description

The AS3490 is an inductive highly efficient DCDC boost

converter. The DCDC converter operates at a fixed fre-

quency of 2MHz and includes soft startup to allow easy

integration into noise sensitive RF systems. A predict-

able startup is guaranteed even with very low duty cycle

PWM input signals. The voltage on the output capacitor

is controlled to minimize ripple and to avoid any acoustic

effects for low frequency PWM input signals.

The output of the DCDC converter is used for five cur-

rent sources connected to up to 6 LEDs. If a current

source is not required, it shall be connected to VOUT or

GND - the AS3490 detects this condition and disables

this current source automatically; this keeps the effi-

ciency of the system constantly high.

The AS3490 is controlled by one enable input, ON. This

input can also be used to connect a PWM input (like

DLS or DBC).

The AS3490 includes several protection functions like

undervoltage lockout, overcurrent and overtemperature.

No microvias are required to assemble the AS3490.

The AS3490 is available in a space-saving WL-CSP

package measuring only 1.7x1.4x0.5mm and operates

over the -30ºC to +85ºC temperature range.

Figure 1. AS3490 Typical Operating Circuit

2 Key Features



2 MHz DCDC Boost converter

- Small 4.7µH external coil

- Very high system efficiency of 86% (DCDC and

current sources combined)

- Very low voltage changes on output to avoid

acoustic noise on output capacitor even with PWM

- Smooth startup even under low duty cycle PWM

conditions



Three Current sources up to 25mA

- Low voltage compliance (150mV)

- High side current source to simplify layout and

thermal management of the LEDs

- Automatically detect and disable failing or not used

LEDs to keep efficiency high

- Current matching <4%

- Current accuracy <7.5%



Excellent LED current output ripple <500µA



Support DLS (Dynamic Luminance Scaling or DBC)



Undervoltage lockout and overcurrent protection



Overtemperature protection



Available in a tiny WL-CSP package

- 3x4 balls, 0.4mm pitch, 1.7x1.4x0.5mm

3 Applications

Display backlight driver for mobile phones, digital cam-

eras, PND and PMPs.





 





 

 



AS3490