RE46C109

Voltage Regulator, Voltage Converter and

R&E International

Piezoelectric Horn Driver

A Subsidiary of Microchip Technology Inc.

Product Specification

© 2009 Microchip Technology Inc.

DS22168A-page 6

Device Operation

(Please refer to the functional block diagram)

The RE46C109 consists of the following main functional blocks: band gap voltage reference, low drop-out voltage

regulator (with over voltage clamp and power supply brownout protection), low battery detection, switched

capacitor 12 volt boost regulator, horn driver and Interconnect logic.

When power is applied the band gap voltage reference and the voltage regulator output are initially enabled. The

low battery detection, horn driver outputs and switched capacitor 12v boost regulator are enabled by TTL

compatible positive logic control inputs.

When the HRNEN (Horn Enable) input is brought to a logic high level, the horn driver outputs as well as the 12v

boost regulator become active. The 12v boost regulator supplies the horn driver outputs. The 12v boost regulator

utilizes a charge pump to boost the Vdd supply input to a regulated 12-volt output. The charge pump consists of

an internal oscillator that is controlled in a voltage comparator feedback configuration.

The low battery detection is enabled and strobed when the LBST input is brought to a logic high level. The LBAT

output is a voltage follower amplifier whose input is determined by a resistor divider across the device supply rails.