LP2950_1 Datasheet, PDF (12/14 Pages) First Components International – 150mA Low Drop Out Voltage Regulators

TYPICAL APPLICATIONS (Continued)
2 Ampere Low Dropout Regulator
CURRENT
LIMIT SECTION
+V_IN = V_OUT +.5V
680
0.05
470
2N3906
4.7MΩ
8
+V_IN
ERROR ⁵
LP2951
3 _SD
7
FB
220
20kΩ
.033
GND
4
V_OUT
1
10kΩ
MJE2955
+V_OUT@ 2A
ERROR
FLAG
+
R₁
1%
+
4.7
TANT.
100µF
R₂
VOUT = 1.23V(1+R1/R2)
For 5V V_OUT, use internal resistors. Wire pin 6 to 7 and pin 2 to +V_OUTBuss.
LP2950/LP2951
Regulator with Early Warning and Auxiliary Output
+V_IN
D₁
8
2
+V_IN
SENSE
6
V_TAP
1
V_OUT
LP2951
7 ^FB
#1
5
ERROR
GND
4
D₂
5V MEMORY
SUPPLY
+
1µF
20
3.6V
NICAD
2.7MΩ
27 kΩ
D₃
D₄
EARLY WARNING
Q₁
8
2
+V_IN
6
V_TAP
SENSE
V_OUT
7 _{FB LP2951}
#2
3 _SD
ERROR ⁵
GND
4
330 kΩ
MAIN 5V OUTPUT
RESET
µP
V_DD
+
1µF
• Early warning flag on low input voltage
• Main output latches off at lower input voltages
• Battery backup on auxiliary output
Operation: Reg.#1’s V_OUT is programmed one diode drop above 5V. It’s error flag
becomes active when V_IN≤ 5.7V. When V_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.
1A Regulator with 1.2V Dropout
UNREGULATED
INPUT
1ΜΩ
1µF
10kΩ
0.01µF
8
6
V_TAP
IN
2
SENSE
LP2951
7
FB
GND
4
OUT ¹
0.002µF
SUPERTEX
VP12C
OUTPUT
5V ± 1% @
+
0 TO 1A
220µF
2kΩ
I_Q ≅ 400µA
Latch Off When Error Flag Occurs
+V_IN
470kΩ
8
5
+V_IN
ERROR
V_OUT
1
470kΩ
V_OUT
LP2951
R₁
3 _SD
7
FB
+
1µF
RESET
GND
4
R₂
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