CA3140_05 Datasheet, PDF (14/23 Pages) Intersil Corporation – 4.5MHz, BiMOS Operational Amplifier with MOSFET Input/Bipolar Output

CA3140, CA3140A
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 3kΩ and 100kΩ 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
+30V
2N6385
CURRENT
POWER DARLINGTON LIMITING
ADJUST
D2201
3
2
OUTPUT
0.1 ⇒ 24V
AT 1A
75Ω 1kΩ 1kΩ
1
100Ω
1
+
2.7kΩ 10µF _-
INPUT
2.2kΩ
10 11
12
3kΩ
8
7
6 CA3140
5
100kΩ ¹ ₄
1kΩ
2
2N2102
3
1kΩ
56pF
2
1kΩ
3
180kΩ
82kΩ
+
- ^{5µF 50kΩ}
14
VOLTAGE
ADJUST
100kΩ
+
- ^250µF
9
3
12
87
5
13
0.01µF
6
4
CA3086
1kΩ
62kΩ
(MHEUAMSAUNRDEMNEONISTEBOAUNTDPWUITDT<H20~^0µ1V0M^RMH^Sz)
LINE REGULATION 0.1%/V
LOAD REGULATION
(NO LOAD TO FULL LOAD)
<0.02%
FIGURE 16. REGULATED POWER SUPPLY
regulation also remains constant. Line regulation is 0.1% per
volt. Hum and noise voltage is less than 200µV 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
20Ω load at 20V output.
+30V
“FOLDBACK” CURRENT
LIMITER
2N5294
D2201
2
3
OUTPUT ⇒ 0V TO 25V
25V AT 1A
“FOLDS BACK”
TO 40mA
1kΩ 200Ω
1
100kΩ 3kΩ
100kΩ
+
2.7kΩ 10µF _-
INPUT
2.2kΩ
10 11
12
2N2102
8
7
6 CA3140
5
100kΩ ¹ ₄
1kΩ
56pF
2
1kΩ
3
180kΩ
82kΩ
+
- ^{5µF 50kΩ}
14
VOLTAGE
ADJUST
100kΩ
+
- ^250µF
9
3
12
87
5
13
0.01µF
6
4
CA3086
1kΩ
62kΩ
(MHEUAMSAUNRDEMNEONISTEBOAUNTDPWUITDT<H20~^0µ1V0M^RMH^Sz)
LINE REGULATION 0.1%/V
LOAD REGULATION
(NO LOAD TO FULL LOAD)
<0.02%
FIGURE 17. REGULATED POWER SUPPLY WITH “FOLDBACK”
CURRENT LIMITING
5V/Div., 1s/Div.
FIGURE 18A. SUPPLY TURN-ON AND TURNOFF
CHARACTERISTICS
Top Trace: Output Voltage;
200mV/Div., 5µs/Div.
Bottom Trace: Collector of load switching transistor, load = 1A;
5V/Div., 5µs/Div.
FIGURE 18B. TRANSIENT RESPONSE
FIGURE 18. WAVEFORMS OF DYNAMIC CHARACTERISTICS OF POWER SUPPLY CURRENTS SHOWN IN FIGURES 16 AND 17
14
FN957.10
July 11, 2005