MC33680 Dual DC−DC
Regulator for Electronic Organizer
The MC33680 is a dual DC−DC
regulator designed for electronic organizer applications.
Both
regulators apply Pulse−Frequency−Modulation (PFM).
The main step−up
regulator output can be externally adjusted from 2.
7V to 5V.
An internal synchronous rectifier is used to ensure high efficiency (achieve 87%).
The auxiliary
regulator with a built−in power
transistor can be configured to produce a wide range of positive voltage (can be used for LCD contrast voltage).
This voltage can be adjusted from +5V to +25V by an external potentiometer.
The MC33680 has been designed for battery powered hand−held products.
With the low start−up voltage from 1V ...