LT3023
13
3023fa
C
BYP
(pF)
10
0.1
STARTUP TIME (ms)
1
10
100
100 1000 10000
3023 TA02c
V
SHDN1/SHDN2
1V/DIV
V
OUT1
1V/DIV
V
OUT2
1V/DIV
2ms/DIV
3023 TA02b
OUT1
BYP1
ADJ1
OUT2
BYP2
ADJ2
IN
SHDN1
SHDN2
LT3023
1μF
V
IN
3.7V TO 20V
OFF ON
0.01μF
0.01μF
422k
261k
249k
249k
10μF
10μF
3023 TA02a
3.3V
AT 100mA
2.5V
AT 100mA
GND
TYPICAL APPLICATIONS
APPLICATIONS INFORMATION
In circuits where a backup battery is required, several
different input/output conditions can occur. The output
voltage may be held up while the input is either pulled
to ground, pulled to some intermediate voltage or is left
open circuit. Current fl ow back into the output will follow
the curve shown in Figure 6.
When the IN pin of the LT3023 is forced below the OUT1
or OUT2 pins or the OUT1/OUT2 pins are pulled above the
IN pin, input current will typically drop to less than 2μA.
This can happen if the input of the device is connected
to a discharged (low voltage) battery and the output is
held up by either a backup battery or a second regulator
circuit. The state of the SHDN1/SHDN2 pins will have no
effect on the reverse output current when the output is
pulled above the input.
Figure 6. Reverse Output Current
Noise Bypassing Slows Startup, Allows Outputs to Track
Startup Time
OUTPUT VOLTAGE (V)
100
90
80
760
60
50
40
30
20
10
0
REVERSE OUTPUT CURRENT (μA)
3023 F06
0123
4
5
678910
T
A
= 25°C
V
IN
= 0V
V
OUT
= V
ADJ
CURRENT FLOWS
INTO OUTPUT PIN
