Data Sheet
ADP122/ADP123
–10
5
4
3
2
1
0
–20
I
I
I
I
I
I
= 100µA
= 1mA
= 10mA
= 100mA
= 200mA
= 300mA
OUT
OUT
OUT
OUT
OUT
OUT
V
= 4.2V
OUT
V
–30
–40
–50
–60
–70
–80
–90
–100
= 3.3V
OUT
V
= 2.8V
OUT
V
V
C
= V
+ 0.5V
= 50mV
IN
RIPPLE
= C
OUT
1µF
IN
OUT
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
10k
100k
1M
10M
FREQUENCY (Hz)
Figure 21. Power Supply Rejection Ratio vs. Frequency, VOUT = 4.2 V, VIN = 4.7 V
Figure 24. Output Noise Spectrum
70
65
60
55
50
45
40
35
30
–10
–20
V
V
= 4.2V
= 3.3V
OUT
OUT
V
V
V
V
V
V
= 2.8V, I
= 3.3V, I
= 4.2V, I
= 2.8V, I
= 3.3V, I
= 4.2V, I
= 1mA
= 1mA
= 1mA
= 300mA
= 300mA
= 300mA
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
–30
–40
–50
–60
–70
–80
–90
–100
V
= 2.8V
OUT
V
V
C
= V
+ 0.5V
1µF
IN
OUT
= 50mV
RIPPLE
= C
IN
OUT
0.001
0.01
0.1
1
(mA)
10
100
1000
10
100
1k
10k
100k
1M
10M
I
FREQUENCY (Hz)
OUT
Figure 22. Power Supply Rejection Ratio vs. Frequency, Various Output
Voltages and Load Currents
Figure 25. Output Noise vs. Load Current and Output Voltage
–10
V
V
V
V
V
V
V
V
= 3.1V, I
= 3.3V, I
= 3.8V, I
= 4.8V, I
= 3.1V, I
= 3.3V, I
= 3.8V, I
= 4.8V, I
= 1mA
= 1mA
= 1mA
= 1mA
= 300mA
= 300mA
= 300mA
= 300mA
IN
IN
IN
IN
IN
IN
IN
IN
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
I
OUT
–20
–30
–40
–50
–60
–70
–80
–90
–100
1mA TO 300mA LOAD STEP
1
V
OUT
2
V
= 50mV
1µF
RIPPLE
= C
C
IN
OUT
V
V
= 3.7V
= 3.3V
IN
OUT
CH1 200mA Ω BW CH2 50.0mV
M 40.0µs A CH1
196mA
B
W
10
100
1k
10k
100k
1M
10M
T
10.20%
FREQUENCY (Hz)
Figure 26. Load Transient Response, COUT = 1 μF
Figure 23. Power Supply Rejection Ratio vs. Headroom Voltage (VIN − VOUT),
OUT = 2.8 V
V
Rev. E | Page 9 of 24