Power Supply & Management IC for Handheld Electronic Products

The MC34280 is a power supply integrated circuit which provides two boost regulated outputs and some power management supervisory functions. 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; or by a microprocessor, digitally through a 6–bit internal DAC.

FEATURES:

• Low Input Voltage, 1V up

• Low Quiescent Current in Standby Mode: 35µA typical

• PFM and Synchronous Rectification to ensure high efficiency (87 @200mA Load)

• Adjustable Main Output: nominal 3.3V @ 200mA max, with 1.8V input

• Auxiliary Output Voltage can be digitally controlled by microprocessor

• Auxiliary Output Voltage:

+5V @ 25mA max, with 1.8V input

+25V @ 15mA max, with 1.8V input

• Current Limit Protection

• Power–ON Reset Signal with Programmable Delay

• Battery Low Detection

• Lithium Battery Back–up

• 32–Pin LQFP Package

APPLICATIONS:

• Digital Organizer and Dictionary

• Personal Digital Assistance (PDA)

• Dual Output Power Supply (For MPU, Logic, Memory, LCD)

• Handheld Battery Powered Device (1–2 AA/AAA cell)