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RC2951
PRODUCT SPECIFICATION
8
P
Typical Applications
(continued)
RC2951
#1
Figure 7. Regulator with Early Warning and Auxillary Output
Figure 10. 5V Regulator with 2.5V Sleep Function
Figure 11. Open Circuit Detector for 4mA to 20mA Current Loop
Figure 8. Latch Off When Error Flag Occurs
Figure 9. 2 Ampere Low Dropout Regulator
2.7M
27k
330k
Main 5V Output
7
7
6
4
4
3
5
5
1
1
47
220
8
8
2
20
470
4.7M
47k
470k
470k
470k
200k
100k
100k
2N3906
100
pF
10k
20k
.033
Error
Flag
680
0.05
MJE2955
2N3906
1
μ
F
1
μ
F
3.6V
Nicad
+
+
+V
IN
+V
IN
= V
OUT
+5.0V
+V
OUT
@ 2A
V
OUT
= 1.23V
For 5V
OUT
,use internal resistors. Wire pin 6 to 7, & wire pin 2 +V
OUT
Buss.
*High input lowers V
OUT
to 2.5V.
1 + R
1
R
2
(
)
D
1
R
1
R
2
R
1
V
IN
V
OUT
R
2
1%
1%
1%
D
2
D
4
D
3
Q
1
5V Memory
Supply
V
TAP
V
OUT
+V
OUT
I
L
< 3.5mA
V
OUT
+V
IN
GND
FB
Current
Limit Section
ERROR
RESET
EARLY WARNING
SENSE
RC2951
#2
μ
P
7
3
6
4
5
1
8
2
V
TAP
V
DD
V
OUT
+V
IN
GND
FB
SD
ERROR
SENSE
Early warning flag on low input voltage
Main output latches of f at lower input voltages
Battery backup on auxillary output
Operation Reg. #1’s V
OUT
is programmed one diode drop above 5V. Its error
flag becomes active when V
in
2
5.7V. WhenV
in
drops below 5.3V, the error
flag of Reg. #2 becomes active and via Q1 latches the main output off.
When V
in
again exceeds 5.7V Reg. #1 is back in regulation and the early
warning signal rises unlatching Reg. #2 via D3.
RC2951
V
OUT
+V
IN
GND
FB
SD
ERROR
4.7
TANT.
+
+
+
100
μ
F
3.3
μ
F
1
μ
F
0.1
μ
F
1N457
360
Min. Voltages
4V
+
RC2951
RC2951
RC2951
3
3
5
5
4
4
4
4
5
1
2
7
7
1N
4001
7
4
+5V
4.7k
Output*
* High for
20mA
8
8
8
C-MOS
GATE
1
1
1
V
OUT
V
OUT
+V
IN
+V
IN
+V
IN
+V
IN
GND
GND
GND
Reset
FB
FB
FB
SD
SD
ERROR
ERROR
Error
Output
*Sleep
Input
Shutdown
Input
2950-13