The AS3607 from austriamicrosystems is a highly integrated power management IC (PMIC) featuring a high level of startup sequence programmability, making it suitable for portable navigation devices, portable media players, e-dictionaries, GPS devices, PDAs and a wide range of battery powered handheld 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 device can be programmed easily for 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 ms or 4 ms, ensuring 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.
In its 6 x 6 mm QFN package, the 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 Li-Ion battery charger. The three step-down converters deliver 700 mA each with an efficiency of up to 95%; the fixed 2 MHz switching frequency minimises PCB footprint by allowing the use of tiny inductors.
The PMIC contains a Li-Ion battery charger with constant current and constant voltage with a maximum charging current of 1 A, 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 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 30 V 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 150 μA 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.
For more information contact ASIC Design Services, +27 (0)11 315 8316, [email protected], www.asic.co.za, Gary de Klerk, NuVision Electronics, +27 (0)11 894 8214, [email protected], www.nuvisionelec.co.za
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