Thursday, January 07, 2010

Power-Management IC Suits Hand-Held Devices

Austriamicrosystems has introduced the AS3607, a highly integrated power-management IC. This PMIC is suitable for portable navigation devices, portable media players, e-dictionaries, GPS devices, PDAs and a range of battery-powered hand-held devices using ARM-based processors. The output voltage and the timing of all regulators of the AS3607 are programmed via software.

With the software and demo board, the OTP memory of the AS3607 can easily be programmed, enabling fast prototype runs. The slope of the ramp can be set for the step-down converters. The user can program the startup sequence with timing steps of 1 or 4ms, insuring that all ARM-based processors can easily be covered. In order to control other parts of the system, the general-purpose I/O pins can be programmed to a specific timing. The PMIC and application processor manage and optimise the power rails within the system to maximise battery charge.

The AS3607 PMIC integrates all the regulators, charger, backlight driver and monitoring functions in a 6 x 6mm QFN package. The AS3607 fully programmable power-management unit includes: three DC-DC step-down converters and five low-noise LDO regulators suitable for RF applications, an LED backlight driver, two programmable current sinks and a powerful Li-ion battery charger. The three step-down converters deliver 700mA each with an efficiency of up to 95 per cent. The fixed 2MHz switching frequency minimises PCB footprint by allowing the use of tiny, low-profile inductors.

The AS3607 contains a Li-ion battery charger with constant current and constant voltage with a maximum charging current of 1A, enabling fast charging of large batteries. An integrated battery switch separates the battery when charging or whenever an external power supply is present. This enables operation of mobile devices with deeply discharged batteries or even with no battery. In order to be compliant to the USB standard the maximum current can be programmed. The integrated DC-DC step-up converter is capable of generating voltages up to 30V to supply OLED displays or LEDs for backlighting LCD displays.

In the case of LEDs two strings of up to eight LEDs can be powered, whereas the current is programmable via registers in 150uA steps, enabling smooth dimming. In addition, an external PWM signal can be used to dynamically control the brightness of the two LED strings. The GPIO pins can be used to get information about charger status, low battery, power-good and power-up key. The AS3607 is available in a QFN36, 6 x 6mm, 0.5mm pitch package and has an operating temperature range of -40 to 85C.

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