MIC5011 Micrel Semiconductor, MIC5011 Datasheet - Page 8

• Manufacturer Part Number: MIC5011
• Description: Minimum Parts High- or Low-Side MOSFET Driver
• Manufacturer: Micrel Semiconductor

MIC5011
Applications Information
Opto-Isolated Interface (Figure 5). Although the MIC5011
has no special input slew rate requirement, the lethargic
transitions provided by an opto-isolator may cause oscilla-
tions on the rise and fall of the output. The circuit shown
accelerates the input transitions from a 4N35 opto-isolator
by adding hysteresis. Opto-isolators are used where the
control circuitry cannot share a common ground with the
MIC5011 and high-current power supply, or where the
control circuitry is located remotely. This implementation is
intrinsically safe; if the control line is severed the MIC5011
will turn OFF.
Industrial Switch (Figure 6). The most common manual
control for industrial loads is a push button on/off switch.
The “on” button is physically arranged in a recess so that in
a panic situation the “off” button, which extends out from the
control box, is more easily pressed. This circuit is compat-
MIC5011
Control Input
Figure 4. Bootstrapped
1
2
3
4
CR2943-NA102A
(GE)
High-Side Driver
V+
Source
Gnd
Input
MIC5011
100nF
Gate
Com
C2
C1
1N5817
8
7
6
5
OFF
ON
(Continued)
+
10µF
7 to 15V
100k
LOAD
330k
1N4001 (2)
IRF540
Figure 6. 50-Ampere
Industrial Switch
1
2
3
4
V+
Source
Gnd
Input
MIC5011
8
Gate
Com
C2
ible with control boxes such as the CR2943 series (GE).
The circuit is configured so that if both switches close
simultaneously, the “off” button has precedence.
This application also illustrates how two (or more) MOSFETs
can be paralleled. This reduces the switch drop, and distrib-
utes the switch dissipation into multiple packages.
High-Voltage Bootstrap (Figure 7). Although the MIC5011
is limited to operation on 4.75 to 32V supplies, a floating
bootstrap arrangement can be used to build a high-side
switch that operates on much higher voltages. The MIC5011
and MOSFET are configured as a low-side driver, but the
load is connected in series with ground.
Power for the MIC5011 is supplied by a charge pump. A
20kHz square wave (15Vp-p) drives the pump capacitor
and delivers current to a 100 F storage capacitor. A zener
C1
8
7
6
5
Control Input
10mA
10µF
+
LOAD
24V
100k
Opto-Isolator Performance
4N35
Figure 5. Improved
IRFP044 (2)
33pF
15V
100k
1k
33k
MPSA05
To MIC5011
July 2000
Input
Micrel