MC34152 Datasheet, PDF (7/10 Pages) ON Semiconductor – HIGH SPEED DUAL MOSFET DRIVERS

MC34152 MC33152
LAYOUT CONSIDERATIONS
High frequency printed circuit layout techniques are
imperative to prevent excessive output ringing and
overshoot. Do not attempt to construct the driver circuit
on wire–wrap or plug–in prototype boards. When driving
large capacitive loads, the printed circuit board must contain
a low inductance ground plane to minimize the voltage spikes
induced by the high ground ripple currents. All high current
loops should be kept as short as possible using heavy copper
runs to provide a low impedance high frequency path. For
optimum drive performance, it is recommended that the initial
circuit design contains dual power supply bypass capacitors
connected with short leads as close to the VCC pin and
ground as the layout will permit. Suggested capacitors are a
low inductance 0.1 µF ceramic in parallel with a 4.7 µF
tantalum. Additional bypass capacitors may be required
depending upon Drive Output loading and circuit layout.
Proper printed circuit board layout is extremely critical
and cannot be over emphasized.
Figure 18. Enhanced System Performance with
Common Switching Regulators
VCC
47 0.1
6
+
–
5.7V
2
Vin
7
TL494
or
TL594
4
5
Figure 19. MOSFET Parasitic Oscillations
Vin
Rg
D1
1N5819
3
The MC34152 greatly enhances the drive capabilities of common switching
regulators and CMOS/TTL logic devices.
Series gate resistor Rg may be needed to damp high frequency parasitic oscillations
caused by the MOSFET input capacitance and any series wiring inductance in the
gate–source circuit. Rg will decrease the MOSFET switching speed. Schottky diode
D1 can reduce the driver’s power dissipation due to excessive ringing, by preventing
the output pin from being driven below ground.
Figure 20. Direct Transformer Drive
Figure 21. Isolated MOSFET Drive
7
4X
1N5819
5
3
3
Output Schottky diodes are recommended when driving inductive loads at high
frequencies. The diodes reduce the driver’s power dissipation by preventing the
output pins from being driven above VCC and below ground.
Isolation
Boundary
1N
5819
MOTOROLA ANALOG IC DEVICE DATA
7