Micrel, Inc.

MIC5019

July 2012

6

Functional Diagram

Functional Diagram with External Components

(High-Side Driver Configuration)

Functional Description

The MIC5019 is a non-inverting device. Applying a logic

high signal to IN (control input) produces gate drive

output. The OUT (Gate Output) is used to turn on an

external N-channel MOSFET.

Supply

VDD (supply) is rated for +2.7V to +9V. An external

capacitor is recommended to decouple noise.

Control

IN is the control input. IN must be forced high or low by

an external signal. Do not leave IN floating as a floating

input may cause unpredictable operation.

A high input turns on Q2, which sinks the output of

current source I1, making the input of the first inverter

low. The inverter output becomes high enabling the

charge pump.

Charge Pump

The charge pump is enabled when IN is logic high. The

charge pump consists of an oscillator and voltage

quadrupler (4×). The output voltage is limited to 16V

typically by a zener diode. The charge pump output

voltage will be approximately:

The oscillator operates from approximately 70kHz to

approximately 100kHz depending upon the supply

voltage and temperature.

OUT

The charge pump output is connected directly to the

OUT pin. The charge pump is active only when IN is

high. When IN is low, Q3 is turned on by the second

inverter and discharges the gate of the external

MOSFET to force it off.

If IN is high, and the voltage applied to VDD drops to

zero, the gate output will be floating (unpredictable).

ESD Protection

D1 and D2 clamp positive and negative ESD voltages.

R1 isolates the gate of Q2 from sudden changes on the

IN input. Q1 turns on if the emitter (IN input) is forced

below ground to provide additional input protection.

Zener D3 also clamps ESD voltages for the OUT (gate

output).