16
(a)No clamp diode (b)Clamp diode only (c)Clamp diode
+ Zener
10k
OUT
GND
IN
2.7k
COM
M63813P/FP/GP/KP
VO(@200mA)=VCE(sat)=0.3V
VCE(sat)
VO
OUT
GND
IN
2.7k
7.2k
COM
3k
M63823P/FP/GP
VO(@200mA)=VBE+VCE(sat)=1.0V
VCE(sat)
VBE
VO
Input voltage waveform
L
H
0V
0V
No clamp diode
Clamp diode V
F
Output voltage waveform
Reverse voltage
Output current waveform
Time t
0mA
V
Z+VF
VS
No clamp diode
Clamp diode +
Zener diode
Clamp diode only
OUT
GND
L
V
S
OUT
GND
L
COM
V
S
OUT
GND
L
COM
V
S
250
0
200
150
100
50
Output saturation voltage and collector current characteristics
0 1.21.00.80.60.40.2
Output saturation voltage VCE(sat) (V)
Collector current IC(mA)
M63813
(IB=2mA)
M63823
(II=0.5mA)
The output transistor formats
are the Darlington type and
the single type. The Darlington type shown in Fig. 6
can generate high operation
current from a minute input
current, but the output saturation voltage is 0.95 to
1.05V. The single type shown
in Fig. 7 can keep the saturation voltage low. The output saturation voltage and
collector current characteristics of these two types are
shown in Fig. 8.
Fig. 6. Darlington type
Fig. 8. Output saturation voltage and
collector current characteristics
Fig. 7. Single type
4
Low output saturation type
Fig. 9. Output voltage and current waveform
during L load operation
Fig. 10. Method for protecting the transistor during L load operation
5
Built-in output clamp diode type
When operating under an inductive(L) load, such as a relay or
motor, the built-in clamp diode shown in Fig. 10(b) is used to
protect the circuit from the reverse voltage that occurs when
the transistor array is turned off.
When only the clamp diode is connected, the flow time of the
current in the clamp diode is long and the switching sometimes
deteriorates a little for relays, etc. as shown in Fig. 9.
When this is a problem, a Zener diode is inserted at the clamp
diode COM terminal(in reverse series) as shown in Fig. 10(c)
to improve the current smooth flow. The Zener diode voltage
(Vz) should be selected such that V
S
+ VZ + VF < V
BR(CEO)
and a voltage type Zener should be used.