CA3140AS INTERSIL [Intersil Corporation], CA3140AS Datasheet - Page 13

• Manufacturer Part Number: CA3140AS
• Description: 4.5MHz, BiMOS Operational Amplifier with MOSFET Input/Bipolar Output
• Manufacturer: INTERSIL [Intersil Corporation]

A small heat sink VERSAWATT transistor is used as the
series pass element in the fold back current system, Figure
17, since dissipation levels will only approach 10W. In this
system, the D2201 diode is used for current sampling.
Foldback is provided by the 3k and 100k divider network
connected to the base of the current sensing transistor.
Both regulators provide better than 0.02% load regulation.
Because there is constant loop gain at all voltage settings, the
FIGURE 18A. SUPPLY TURN-ON AND TURNOFF
FIGURE 16. REGULATED POWER SUPPLY
+30V
(MEASUREMENT BANDWIDTH
INPUT
HUM AND NOISE OUTPUT <200 V
FIGURE 18. WAVEFORMS OF DYNAMIC CHARACTERISTICS OF POWER SUPPLY CURRENTS SHOWN IN FIGURES 16 AND 17
LINE REGULATION 0.1%/V
10
3
9
8
6
2.7k
11
7
POWER DARLINGTON
2.2k
CHARACTERISTICS
10 F
1
2N6385
100
1
3
5
4
-
+
2
62k
5V/Div., 1s/Div.
6
+
-
75
3k
12
100k
~
10MHz)
5 F
CA3086
1k
5
13
CA3140
RMS
CURRENT
LIMITING
ADJUST
14
13
2
7
1
50k
1k
8
4
D2201
(NO LOAD TO FULL LOAD)
1k
2
3
1k
1k
56pF
LOAD REGULATION
VOLTAGE
1k
ADJUST
2N2102
100k
0.01 F
2
<0.02%
180k
82k
0.1
OUTPUT
1
3
AT 1A
24V
+
-
CA3140, CA3140A
250 F
regulation also remains constant. Line regulation is 0.1% per
volt. Hum and noise voltage is less than 200 V as read with a
meter having a 10MHz bandwidth.
Figure 18A shows the turn ON and turn OFF characteristics
of both regulators. The slow turn on rise is due to the slow
rate of rise of the reference voltage. Figure 18B shows the
transient response of the regulator with the switching of a
20 load at 20V output.
FIGURE 17. REGULATED POWER SUPPLY WITH “FOLDBACK”
+30V
Bottom Trace: Collector of load switching transistor, load = 1A;
(MEASUREMENT BANDWIDTH
INPUT
HUM AND NOISE OUTPUT <200 V
Top Trace: Output Voltage;
LINE REGULATION 0.1%/V
10
9
8
6
2.7k
11
7
FIGURE 18B. TRANSIENT RESPONSE
CURRENT LIMITING
2.2k
200mV/Div., 5 s/Div.
5V/Div., 5 s/Div.
10 F
100k
2
1
3
5
4
2N5294
“FOLDBACK” CURRENT
+
-
2
62k
1
6
+
-
100k
12
~
LIMITER
3
10MHz)
5 F
CA3086
1k
5
100k
CA3140
RMS
14
13
7
1
50k
1k
8
4
D2201
(NO LOAD TO FULL LOAD)
1k
2
3
3k
200
56pF
LOAD REGULATION
VOLTAGE
1k
ADJUST
2N2102
100k
0.01 F
OUTPUT
25V AT 1A
“FOLDS BACK”
TO 40mA
<0.02%
180k
82k
+
0V TO 25V
-
250 F