LT1129 Linear Technology, LT1129 Datasheet - Page 11

• Manufacturer Part Number: LT1129
• Description: Micropower Low Dropout Regulators with Shutdown
• Manufacturer: Linear Technology

A
shutdown pin floating (open circuit). Figure 5 shows
output current as a function of output voltage with the
input floating and the shutdown pin pulled to ground.
When the input of the LT1129 is forced to a voltage below
its nominal output voltage and its output is held high, the
output current will follow the curve shown in Figure 6 . This
Table 4. Fault Conditions
0.8V V
0.8V V
PPLICATI
INPUT PIN
Open
Open
0.8V
0.8V
IN
IN
V
V
OUT
OUT
100
350
300
250
200
150
100
50
90
80
70
60
50
40
30
20
10
0
0
Figure 3. Reverse Output Current
0
0
Figure 4. Reverse Output Current
T
V
V
CURRENT FLOWS
INTO DEVICE
O
J
IN
SENSE
V
V
V
LT1129-3.3
= 25°C
1
IN
SHDN
SENSE
= 0V
U
= OPEN
2
1
= V
SHDN PIN
= OPEN
Open (Hi)
Grounded
Open (Hi)
Grounded
Open (Hi)
Grounded
S
= V
OUT
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
3
OUT
LT1129-3.3
I FOR ATIO
U
4
2
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LT1129
5
LT1129-5
6
3
Forced to V
Forced to V
Forced to V
Forced to V
OUTPUT/SENSE PINS
7
W
LT1129-5
8
4
> 1V
> 1V
1129 F04
9
1129 F03
OUT
OUT
OUT
OUT
10
5
(Nominal)
(Nominal)
(Nominal)
(Nominal)
U
Reverse Output Current 15 A (See Figure 3)
Reverse Output Current 15 A (See Figure 3)
Reverse Output Current 200 A Peak (See Figure 4)
Reverse Output Current 35 A at V
Reverse Output Current 300 A Peak (See Figure 6)
Reverse Output Current 300 A (See Figure 6)
can happen if the input of the LT1129 is connected to a
discharged (low voltage) battery and the output is held up
by either a backup battery or by a second regulator circuit.
Users with applications requiring lower reverse currents
should contact the factory about the availability of a
modified version of the LT1129.
LT1129/LT1129-3.3/LT1129-5
350
300
250
200
150
100
40
35
30
25
20
15
10
50
5
0
0
0
0
Figure 5. Reverse Output Current
Figure 6. Reverse Output Current
V
V
V
V
SENSE
IN
SHDN
SENSE
= OPEN
LT1129-3.3
1
1
= V
= 0V
= V
OUT
OUTPUT VOLTAGE (V)
OUT
V
INPUT VOLTAGE (V)
OUT
LT1129-3.3
OUT
= V
2
2
= 3.3V
OUT
(Nominal) (See Figure 5)
3
3
V
LT1129-5
OUT
LT1129-5
= 5V
4
4
1129 F05
1129 F06
5
5
11