Datasheet

LTC1798 Series
7
1798fc
LTC1798-5
OUT
IN
GND
4
2
5.2V
TO
12.6V
6
5V
1798 F02
0.1µF
C
OUT
>1µF
DAMPING RESISTOR
<1k
APPLICATIONS INFORMATION
Figure 2. Adding a Damping Resistor with
Output Capacitors Greater Than 1µF
Figure 3. Damping Resistance vs Output Capacitor Value
OUTPUT CAPACITOR VALUE (µF)
1
10
RESISTOR VALUE (Ω)
100
1k
10k
10 100 1000
1798 F03
These references consume only 4µA of quiescent current
under light and heavy loads as well as in dropout; whereas,
PNP-based references waste considerable amounts of cur-
rent when the pass transistor is saturated. In addition, the
LTC1798 series provides a lower dropout voltage (200mV
max) than PNP-based references.
to reduce the output ringing. Figure 2 illustrates the use of
a damping resistor for capacitive loads greater than 1µF.
Figure 3 shows the resistor and capacitor values required
to achieve critical damping.
Internal P-Channel Pass Transistor
The LTC1798 series features an internal P-channel MOSFET
pass transistor. This provides several advantages over
similar designs using a PNP bipolar pass transistor.