Datasheet

LTC1798 Series
5
1798fc
TYPICAL PERFORMANCE CHARACTERISTICS
5µV/DIV
1798 G10
1SEC/DIV
V
IN
= 2.7V
INPUT VOLTAGE (V)
0 1 2 3 4 5 6 7 8 9 10
INPUT CURRENT (µA)
1798 G11
1400
1200
1000
800
600
400
200
0
T
A
= –55°C
T
A
= 25°C
T
A
= 125°C
INPUT VOLTAGE (V)
0
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
INPUT CURRENT (µA)
1798 G12
250
200
150
100
50
0
T
A
= 25°C
T
A
= –55°C
T
A
= 125°C
LTC1798-2.5
0.1Hz to 10Hz Noise
LTC1798-5 Input Current
vs Input Voltage in Dropout
LTC1798-2.5 Input Current
vs Input Voltage in Dropout
PIN FUNCTIONS
DNC (Pins 1, 5, 7, 8): Do Not Connect. Connected
internally for post package trim. These pins must be left
unconnected.
IN (Pin 2): Positive Supply. Bypassing with a 0.1µF capaci-
tor is recommended if the output loading changes. (V
OUT
+ 0.2V) ≤ V
IN
≤ 12.6V.
DNC (Pin 3): (LTC1798-2.5/LTC1798-3/LTC1798-4.1/
LTC1798-5) Do Not Connect. Connected internally for post
package trim. This pin must be left unconnected.
FB (Pin 3): (LTC1798) Resistor Divider Feedback Pin.
Connect a resistor divider from OUT to GND and the center
tap to FB. This pin sets the output potential.
VV
RR
R
OUT
=
+






2 385
12
2
.;
R1 is connected from OUT
to FB and R2 from FB to GND. Selecting R2 ≥ 10k will
make I
OUT
< 250µA.
GND (Pin 4): Negative Supply or Ground Connection.
OUT (Pin 6): Reference Output. The output can source
up to 10mA and sink up to 2mA. It is stable with output
bypass capacitor ranging from 0µF to 1µF.