MIC5010 Datasheet, PDF (13/16 Pages) Micrel Semiconductor – Full-Featured High- or Low-Side MOSFET Driver

MIC5010
Applications Information (Continued)
15V
Micrel
1N4003 (2)
100kΩ
10mA
Control Input
4N35
MIC5010
1 _{Inhibit Fault} 14
33pF
33kΩ
MPSA05
6.2kΩ
2 _NC
3 _Input
4 _Thresh
5 _Sense
V+ ¹³
NC ¹²
C1 ¹¹
Com ¹⁰
6 _{Source C2 9}
100kΩ
7 _{Gnd Gate} 8
1N4746
+
100µF
90V
1nF
IRFP250
100nF
200V
15Vp-p, 20kHz
Squarewave
1N4003
1kΩ
Figure 10. High-Voltage
Bootstrapped Driver
1/4 HP, 90V
5BPB56HAA100
(GE)
10mΩ
KC1000-4T
(Kelvin)
M
cross conduction. Both the top- and bottom-side drivers are could be independently driven from an external source such
protected, so the output can be shorted to either rail without as a switch or another high-side driver to give a delay
5
damage.
relative to some other event in the system.
The top-side driver is based on the bootstrapped circuit of
Figure 6, and cannot be switched on indefinitely. The
bootstrap capacitor (1µF) relies on being pulled to ground
by the bottom-side output to recharge. This limits the
maximum duty cycle to slightly less than 100%.
Hysteresis has been added to guarantee clean switching at
turn-on. Note that an over-current condition latches the
relay in a safe, OFF condition. Operation is restored by
either cycling power or by momentarily shorting pin 3 to
ground.
Two of these circuits can be connected together to form an
H-bridge. If the H-bridge is used for locked antiphase
control, no special considerations are necessary. In the
case of sign/magnitude control, the “sign” leg of the H-
bridge should be held low (PWM input held low) while the
other leg is driven by the magnitude signal.
If current feedback is required for torque control, it is
available in chopped form at the bottom-side driver's 22mΩ
current-sensing resistor.
Time-Delay Relay (Figure 12). The MIC5010 forms the
basis of a simple time-delay relay. As shown, the delay
commences when power is applied, but the 100kΩ/1N4148
Motor Driver with Stall Shutdown (Figure 13). Tachom-
eter feedback can be used to shut down a motor driver
circuit when a stall condition occurs. The control switch is a
3-way type; the “START” position is momentary and forces
the driver ON. When released, the switch returns to the
“RUN” position, and the tachometer's output is used to hold
the MIC5010 input ON. If the motor slows down, the tach
output is reduced, and the MIC5010 switches OFF. Resis-
tor “R” sets the shutdown threshold. If the output current
exceeds 30A, the MIC5010 shuts down and remains in that
condition until the momentary “RESET” button is pushed.
Control is then returned to the START/RUN/STOP switch.
April 1998
5-99