MIC5019 Datasheet, PDF (6/12 Pages) Micrel Semiconductor – Ultra-Small High-Side N-Channel MOSFET Driver with Integrated Charge Pump

Micrel, Inc.
Functional Diagram
MIC5019
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:
V_OUT = 4 × V_DD – 2.8V, but not exceeding 19Vmax.
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).
July 2012
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