MC3392 Datasheet, PDF (6/12 Pages) Motorola, Inc – LOW SIDE PROTECTED SWITCH

Figure 11. Turn–On Waveform
MC3392
IO
760 mA
IO
Vout
+VS = 14 V
RL = 17 Ω
TA = 25°C
14 V
Vout
4.0 V
1.0 V
Vin
Figure 12. Turn–Off Waveform
+VS = 14 V
RL = 17 Ω
TA = 25°C
1.5
1.25
1.0
0.75
0.5
0.25
0
0
Figure 13. Output Current versus
Supply Voltage
Vin = 4.0 V
RL = 0
TA = 25°C
No Heatsink
Infinite Heatsink
10
20
30
40
50
60
+VS, SUPPLY VOLTAGE (V)
Figure 14. Maximum Load Inductance
versus Output Current
0.5
Emax = 60 mJ
0.4
0.3
External Clamp Needed
0.2
0.1 Safe Operating Region
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
IO, OUTPUT CURRENT (A)
TECHNICAL DISCUSSION
Introduction
The MC3392 is a low side protected switch incorporating
many features making it ideal for use in harsh automotive
applications. The protection circuitry of the MC3392 protects
not only itself but also the associated load from destructive
voltage transients attributed to load and field dump, as well as
reverse and double battery conditions found in automotive
applications. The MC3392 is unique in that the protection
circuitry is internal and does not require additional external
protection components for its operation. This makes the
device very cost effective because its application utilizes few
external components, thus reducing cost and space
requirements needed for the system. The MC3392 is
extremely effective when used to drive solenoids, as well as
incandescent lamp loads. The following description of the
device’s operation is in reference to the functional blocks of
the Representative Block Diagram shown in Figure 1.
CMOS Input
The input of the MC3392 is CMOS compatible. Input
control performs as true logic. When the input (Vin) is less
than 1.0 V the MC3392 switch is in a high impedance or OFF
state. When Vin is greater than 4.0 V, is in a low impedance or
ON state. The switching threshold of the input is
approximately 2.0 V and is graphed in Figure 7. With the input
at 4.0 V, the input sink current will be approximately 250 µA.
In the ON state, the internal protection circuitry is activated
and all of the protection features are available for use. In the
OFF state, however, it is important to note that none of the
protection features are available, with the exception of the
internal inductive load clamp. The input pin is afforded a
minimum of 2000 V ESD protection (Human Body Model) by
virtue of the 7.2 V zener diode.
6
MOTOROLA ANALOG IC DEVICE DATA