CA3273
VCC
INPUT 1
OUTPUT PASS
RS
TRANSISTOR
BANDGAP
VOLTAGE/CURRENT
REFERENCE
OVER-VOLTAGE
SHUTDOWN
THERMAL
LIMIT
CURRENT
LIMIT
OUTPUT DEVICE
BASE DRIVE
CONTROL CIRCUIT
VO
3 OUTPUT
FIGURE 1. FUNCTIONAL BLOCK DIAGRAM OF CA3273
2
VSW
CONTROL INPUT
VZ
VCC
+4 TO +24V
(SUPPLY INPUT)
ON
CONTROL
INPUT
CA3273
VSW
VO
L
OFF
1KΩ
2N5320
OR EQUIVALENT
FIGURE 2. TYPICAL APPLICATION WITH ZENER DIODE FOR
OVER-VOLTAGE PROTECTION WITH INDUCTIVE
LOAD SWITCHING. VZ SHOULD BE LESS THAN
35V. WHEN CURRENT IS SWITCHED OFF IN THE
OUTPUT LOAD (L), THE INDUCTIVE KICK PULSE
GOES NEGATIVE. THE CLAMPED CLAMP LEVEL
OF THE NEGATIVE GOING PULSE IS VCC - VZ.
VCC
VO
CA3273
VSW
RL
40Ω
ON
OFF
CONTROL
INPUT
1KΩ
VZ
2N5320
OR EQUIVALENT
FIGURE 3. OPTIONAL RANGE SHIFTING OF THE VCC INPUT
VOLTAGE USING A ZENER DIODE TO OFFSET
THE VSW CONTROL PIN. (I.E.,THE OVER-VOLT-
AGE SHUTDOWN THRESHOLD WILL BE IN-
CREASED TO VCC(THD) + VZ AND THE MINIMUM
VCC OPERATING VOLTAGE IS VZ + 4V).
2
DERATING 70oC/W
(WITHOUT HEAT SINK)
1
RESISTIVE
LAMP
SOLENOID
0
-50 -25
0
25
50
75
TEMPERATURE (oC)
100 125 150
FIGURE 4. DISSIPATION DERATING CURVES
RELAY
FIGURE 5. TYPICAL LOADS
3-5