Micrel

MIC4834

October 2008

5

M9999-100908-A

Functional Diagram

Figure 1. MIC4834 Block Diagram

Functional Description

Overview

The MIC4834 is a high-voltage dual output EL driver with

a peak-to-peak AC output voltage of 220V capable of

driving two 3 in

panels by converting a low DC input voltage to a high

DC high output voltage using the boost regulator circuit

and then alternating the high DC voltage across the EL

panel using an H-Bridge. Input supply current for the

MIC4834 is typically 152µA. The high voltage EL driver

has two internal oscillators to control the boost switching

frequency and the H-bridge driver frequency. The

internal boost oscillator frequency can be individually

programmed through an external resistor to maximize

efficiency and brightness of the EL panel. The H-bridge

frequency is internally fixed at 225Hz to reduce external

component count.

R

egulation

When the internal feedback voltage is less than the

reference voltage, the internal comparator enables

switching in the boost circuit. When the boost regulator

is switching, current flows through the inductor into the

switch. The switching MOSFET will typically turn on for

90% of the switching period. During the on-time, energy