LT1185 LINER [Linear Technology], LT1185 Datasheet - Page 13

• Manufacturer Part Number: LT1185
• Description: Low Dropout Regulator
• Manufacturer: LINER [Linear Technology]

V
+
–
TYPICAL APPLICATIO S
V
+
IN
–
IN
***I
+
**FOR LONG DELAY TIMES, REPLACE D2 WITH 2N3906 TRANSISTOR AND USE R3 ONLY FOR
*SEE CHART FOR DELAY TIME VERSUS (C3)(R3//R
†
D3 PROVIDES FAST RESET OF TIMING. INPUT MUST DROP TO A LOW VALUE TO RESET TIMING
ALL DIODES 1N4148
CALCULATING DELAY TIME. R3 CAN INCREASE TO 100k
COEFFICIENT OF I
FOR COLD OPERATION
LIM
+
C2
2.2 F
IS 11k/R
D3
C2
2.2 F
TANT
†
0.01
R5*
LIM
R3**
15k
R6**
1k
C3*
, INSTEAD OF 15k, BECAUSE OF VOLTAGE DROP IN D1. TEMPERATURE
LIM
WILL BE 0.11%/ C, SO ADEQUATE MARGIN MUST BE ALLOWED
D2
R3
360k
R4**
1k
Q1**
Time Delayed Start-Up
V
V
IN
IN
REF
REF
OPTIONAL HYSTERSIS
3
2
R
D1
4k
LIM
Low Input Voltage Monitor Tracks Dropout Characteristics
+
–
LT1006
LT1185
U
LT1185
***
V
LIM
27k
R7
–
4
) PRODUCT
2M
†
V
GND
+
7
GND
LT1185 • TA05
V
V
OUT
FB
OUT
FB
R1
2.37k
R2
R1
2.37k
R2
2.6k
“LOW” FOR LOW INPUT
OUTPUT SWINGS FROM V
+
+
C1
2.2 F
TANT
LT1185 • TA06
C1
2.2 F
TANT
V
OUT
+
–
V
OUT
+
–
IN
+
TO V
IN
**R4 DETERMINES TRIP POINT AT I
*3" #26 WIRE
†
–
DO NOT SUBSTITUTE. OP AMP MUST HAVE COMMON MODE
R6 DETERMINES INCREASE OF TRIP POINT AS I
TRIP POINT FOR V
FOR VALUES SHOWN, TRIP POINT FOR V
RANGE EQUAL TO NEGATIVE SUPPLY
V
OUT
+ 0.37V AT I
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
IN
*t = (R3//R
OUT
= V
5
OUT
= 0 AND V
INPUT VOLTAGE (V)
1 + R4 • R7
10
LIM
Delay Time
R3 • R6
OUT
)(C3) =
OUT
15
= 0
= 1.18V AT I
IN
R3 + R
R3 • R
+ I
IS:
LT1185
20
OUT
OUT
LIM
LIM
R5 • R7
OUT
13
INCREASES
R6
25
LT1185 • TA07
(C3)
= 3A
30