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.

FEATURES:
• Low Input Voltage, 1V up
• Low Quiescent Current in Standby Mode: 35µA typical
• PFM and Synchronous Rectification to ensure high efficiency
    (87% @60mA Load)
• Adjustable Main Output: +2.7V to +5V
    nominal 3.3V @ 100mA max, with 1.8V input
• Auxiliary Output Voltage: +5V to +25V
    +5V @ 25mA max, with 1.8V input
    +25V @ 15mA max, with 1.8V input
• Current Limit Protection
• Power–Good Signal with Programmable Delay
• Battery Low Detection
• Lithium Battery or Supercap Back–up
• 32–Pin LQFP Package

APPLICATIONS:
• Digital Organizer and Dictionary
• Dual Output Power Supply (For MPU, Logic, Memory, LCD)
• Handheld Battery Powered Device (1–2 AA/AAA cell)