LT1121-3.3 Linear Technology, LT1121-3.3 Datasheet - Page 11

• Manufacturer Part Number: LT1121-3.3
• Description: Micropower Low Dropout Regulators with Shutdown
• Manufacturer: Linear Technology

A
When the input of the LT1121 is forced to a voltage below
its nominal output voltage and its output is held high, the
reverse output current will still follow the curve in Figure
2. This condition can occur if the input of the LT1121 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. When the input pin is forced below the
output pin or the output pin is pulled above the input pin,
the input current will typically drop to less than 2 A (see
Figure 3). The state of the shutdown pin will have no effect
on the reverse output current when the output is pulled
above the input.
Table 6. Fault Conditions
– 30V < V
< V
< V
PPLICATI
INPUT PIN
OUT
OUT
> 1.5V
Open
Open
(Nominal)
(Nominal)
0.8V
0.8V
IN
< 30V
O
U
SHDN PIN
Open (Hi)
Grounded
Open (Hi)
Grounded
Open (Hi)
Grounded
Open (Hi)
Grounded
S
I FOR ATIO
U
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.
Forced to V
Forced to V
Forced to V
Forced to V
W
OUTPUT PIN
OUT
OUT
OUT
OUT
0V
0V
0V
0V
(Nominal)
(Nominal)
(Nominal)
(Nominal)
U
Reverse Output Current 15 A (See Figure 2)
Input Current 1 A (See Figure 3)
Reverse Output Current 15 A (See Figure 2)
Input Current 1 A (See Figure 3)
Reverse Output Current 15 A (See Figure 2)
Reverse Output Current 15 A (See Figure 2)
Output Current = 0
Output Current = 0
Output Current = Short-Circuit Current
Output Current = 0
LT1121/LT1121-3.3/LT1121-5
5
4
3
2
1
0
0
V
V
OUT
OUT
Figure 3. Input Current
= 3.3V (LT1121-3.3)
= 5V (LT1121-5)
1
INPUT VOLTAGE (V)
2
3
4
1121 F03
5
11