MIC5016 Micrel Semiconductor, MIC5016 Datasheet - Page 7

• Manufacturer Part Number: MIC5016
• Description: Low-Cost Dual High- or Low-Side MOSFET Driver
• Manufacturer: Micrel Semiconductor

MIC5016/5017
Typical Applications
Variable Supply Low Side Driver for Motor Speed Control
(Figure 6) The internal regulation in the MIC5016/17 allows
a steady gate enhancement to be supplied while the MIC5016/
17 supply varies from 5V to 30V, without damaging the
internal gate to source zener clamp. This allows the speed of
the DC motor shown to be varied by varying the supply
voltage.
Solenoid Valve Driver (Figure 7) High power solenoid valves
are used in many industrial applications requiring the timed
dispensing of chemicals or gases. When the solenoid is
activated, the valve opens (or closes), releasing (or stopping)
fluid flow. A solenoid valve, like all inductive loads, has a
considerable “kickback” voltage when turned off, as current
cannot change instantaneously through an inductor. In most
Figure 6: DC Motor Speed Control/Driver
OFF
ON
10µF
V+
Input
Source
Gnd
1/2 MIC5017
Figure 5. High Side Driver with Delayed Overcurrent Shutdown
1k
Gate
V
V+
Input
Source
Gnd
CC
1/2 MIC5017
= +5V to +30V
M
IRF540
Gate
R
0.06
S
1k
R4
12V
5-152
1000pF
R1
1k
R2
120k
On
applications, it is acceptable to allow this voltage to momen-
tarily turn the MOSFET back on as a way of dissipating the
inductor's current. However, if this occurs when driving a
solenoid valve with a fast switching speed, chemicals or
gases may inadvertantly be dispensed at the wrong time with
possibly disasterous consequences. Also, too large of a
kickback voltage (as is found in larger solenoids) can damage
the MIC5016 or the power FET by forcing the Source node
below ground (the MIC5016 can be driven up to 20V below
ground before this happens). A catch diode has been
included in this design to provide an alternate route for the
inductive kickback current to flow. The 5k resistor in series
with this diode has been included to set the recovery time of
the solenoid valve.
LM301A
OFF
ON
0.01µF
Figure 7: Solenoid Valve Driver
1
2
3
4
2.2k
Gnd
Trigger
V
R/C
REF
LM3905N
12V
Logic
V+
Input
Source
Gnd
Emit
Coll
1/2 MIC5016
V+
8
7
6
5
Gate
Solenoid
ASCO
8320A
24V
IRFZ40
5k
1N4005
October 1998
Micrel