Datasheet

 2012 Microchip Technology Inc. DS25160A-page 13
MCP1755/1755S
Note 1: Unless otherwise indicated V
R
=3.3V, C
OUT
= 1 µF Ceramic (X7R), C
IN
= 1 µF Ceramic (X7R), I
L
=1mA,
T
A
=+25°C, V
IN
=V
R
+1V or V
IN
= 3.6V (whichever is greater), SHDN =V
IN
, package = SOT-223
FIGURE 2-25: Power Supply Ripple
Rejection vs. Frequency.
FIGURE 2-26: Output Noise vs. Frequency
(3 lines, V
R
= 1.8V, 3.3V, 5.0V).
FIGURE 2-27: Start-up from V
IN
.
FIGURE 2-28: Start-up from SHDN
.
FIGURE 2-29: Short Circuit Current
Foldback.
FIGURE 2-30: Short Circuit Current
Foldback.
70
-60
-50
-40
-30
-20
-10
0
PSRR (dB)
V
OUT
= 5.0V
V
IN
= 6.5V
V
INAC
= 1Vpk-pk
C
IN
= 0 µF
I
OUT
= 10 mA
I
OUT
=
300 mA
-100
-90
-80
-
70
0.01 0.1 1 10 100
Frequency (kHz)
I
OUT
300 mA
0.100
1.000
10.000
u
t Noise (μV/Hz)
C
IN
= 1 μF, C
OUT
= 1 μF, I
OUT
= 50 mA
V
OUT
= 1.8V
V
IN
= 3.6V
V
OUT
=
50V
0.010
0.100
0.01 0.1 1 10 100 1000
Outp
u
Frequency (kHz)
V
OUT
5
.
0V
V
IN
= 6.0V
V
OUT
= 3.3V
V
IN
= 4.3V
4.3V
0VV
IN
3.3V
3.3V
0V
0V
V
OUT
PWRGD
Time=80 µs/Div
PWRGD=10K to V
OUT
I
LOAD
=1 mA
V
IN
=0 to 4.3V
V
OUT
=3.3V
4.3V
0V
SHDN
3.3V
3.3V
0V
0V
V
OUT
PWRGD
Time=80 µs/Div
PWRGD=10K to V
OUT
I
LOAD
=1 mA
V
IN
=4.3V
V
OUT
=3.3V
06
0.8
1.0
1.2
1.4
1.6
1.8
2.0
u
tput Voltage (V)
V
IN
= 3.6V
V
OUT
= 1.8V
0.0
0.2
0.4
0
.
6
0 0.1 0.2 0.3 0.4 0.5
O
u
Output Current (A)
Increasing Load
Decreasing Load
10
1.5
2.0
2.5
3.0
3.5
t
put Voltage (V)
V
IN
= 4.3V
V
OUT
= 3.3V
0.0
0.5
1
.
0
0 0.1 0.2 0.3 0.4 0.5
Ou
t
Output Current (A)
Increasing Load
Decreasing Load