RC2951 データシートの表示（PDF） - Fairchild Semiconductor
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RC2951 Datasheet PDF : 11 Pages
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RC2951
PRODUCT SPECIFICATION
Typical Applications (continued)
+VIN
D1
8
2
+VIN
6
VTAP
SENSE
1
VOUT
RC2951
FB
7
#1
5
ERROR
GND
4
D2 5V Memory
Supply
+
1µF
20
3.6V
Nicad
2.7MΩ
27kΩ
D3
D4
EARLY WARNING
Q1
8
2
+VIN
6
VTAP
SENSE
1
VOUT
7 FB RC2951
3
#2
5
SD
ERROR
GND
4
330kΩ
Main 5V Output
RESET
µP
VDD
+
1µF
• 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 VOUT is programmed one diode drop above 5V. Its error
flag becomes active when Vin ≤ 5.7V. WhenVin drops below 5.3V, the error
flag of Reg. #2 becomes active and via Q1 latches the main output off.
When Vin again exceeds 5.7V Reg. #1 is back in regulation and the early
warning signal rises unlatching Reg. #2 via D3.
Figure 7. Regulator with Early Warning and Auxillary Output
+VIN
8
470kΩ
+VIN
5 ERROR
1
VOUT
470kΩ
RC2951
3
SD
7
FB
Reset
GND
4
VOUT
R1
+
1µF
R2
Figure 8. Latch Off When Error Flag Occurs
Current
Limit Section
+VIN = VOUT +5.0V
680
0.05
470
2N3906
4.7MΩ
8
+VIN
ERROR 5
220
20kΩ
RC2951
3
SD
7
FB
GND VOUT
4
1
.033
47
10kΩ
Error
Flag
MJE2955
+VOUT @ 2A
R1 +
+
4.7 100
1% TANT. µF
R2
( ) VOUT = 1.23V
1 + R1
R2
For 5VOUT,use internal resistors. Wire pin 6 to 7, & wire pin 2 +VOUT Buss.
Figure 9. 2 Ampere Low Dropout Regulator
*Sleep
Input
+VIN
C-MOS
GATE
47kΩ
8
470kΩ
Error
Output
+VIN
5 ERROR
1
VOUT
RC2951
Shutdown 3
Input
SD
GND
FB
100
pF
2N3906
+VOUT
200kΩ
+ 3.3µF
1%
100kΩ
4
7
1%
100kΩ
*High input lowers VOUT to 2.5V.
Figure 10. 5V Regulator with 2.5V Sleep Function
4
20mA
1N
4001
0.1µF
8
VIN
VOUT 1
RC2951
FB 7
GND
4
1N457
+5V
4.7kΩ
Output*
1
5
4
2
* High for
IL < 3.5mA
360
Min. Voltages ≈ 4V
2950-13
Figure 11. Open Circuit Detector for 4mA to 20mA Current Loop
8
REV. 1.0.0 2/8/01
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