Datasheet

MAX1857
500mA, Low-Dropout,
Ripple-Rejecting LDO in µMAX
_______________________________________________________________________________________ 5
80
70
60
50
40
30
20
10
0
0.01 1 100.1 100
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX1857 toc04
FREQUENCY (kHz)
PSRR (dB)
1000
C
OUT
= 3.3
µ
F
I
OUT
= 50mA
LOAD-TRANSIENT RESPONSE
MAX1857 toc05
10
µ
s/div
4.80V
0
600mA
4.75V
4.70V
400mA
200mA
A: V
OUT
= 4.75V, 50mV/div
B: I
OUT
= 5mA TO 500mA, 200mA/div
V
IN
= 5.25V, C
IN
= 10
µ
F
A
B
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX1857 toc06
10
µ
s/div
0
4.80V
4.75V
4.70V
4.65V
400mA
200mA
A: V
OUT
= 4.75V, 50mV/div
B: I
OUT
= 5mA TO 500mA, 200mA/div
V
IN
= V
OUT
+ 100mV = 4.85V, C
IN
= 10
µ
F
A
B
SWITCHING POWER-SUPPLY
RIPPLE REJECTION
MAX1857 toc07
2
µ
s/div
5.0V
4.75V
A: MAX1632: V
IN
= 9V, V
OUT
= 5.0V, 20mV/div
B: MAX1857: V
OUT
= 4.75V, I
OUT
= 500mA, 2mV/div
OUT
MAX1632
= IN
MAX1857
A
B
RST WAVEFORM
MAX1857 toc09
20ms/div
A: V
IN
= 0 TO 5.5V, 2V/div
B: V
OUT
= 4.75V, R
OUT
= 95Ω, 2V/div
C: V
RST
, 100kΩ TO OUT, 2V/div
A
B
0
0
0
C
Typical Operating Characteristics (continued)
(V
IN
= +5.25V, V
OUT
= 4.75V, SHDN = IN, SET = GND, C
IN
= 1µF, C
OUT
= 3.3µF, T
A
= +25°C, unless otherwise noted.)
SHUTDOWN WAVEFORM
MAX1857 toc08
40µs/div
6V
2V
A: V
SHDN
= 0 TO 2V, 1V/div
B: V
OUT
= 4.75V, 2V/div
R
OUT
= 9.5Ω (500mA)
A
B
2V
1V
0
4V
0