NCP584
http://onsemi.com
12
APPLICATION INFORMATION
Input Decoupling
A 1.0 mF tantalum capacitor is the recommended value
to be connected between V
in
and GND. For PCB layout
considerations, the traces of V
in
and GND should be
sufficiently wide in order to minimize noise and prevent
unstable operation.
Output Decoupling
It is recommended to use a 2.2 mF or higher tantalum
capacitor on the V
out
pin. For better performance, select a
tantalum capacitor with low Equivalent Series Resistance
(ESR). If you use a tantalum type capacitor with high ESR
value of this capacitor, output might be unstable. For a
ceramic type capacitor it is recommended connection
about 1 W resistor in series for the stability of output
voltage. The relation between Output Current of regulator
and ESR of an output capacitor is shown in Figures 32 to
34. Those charts show minimal value of ESR for stable
output voltage in Fast Transient mode. The minimal ESR
of an output ceramic capacitor in Low Power mode is
40 mW for all output voltages. For PCB layout
considerations, place the output capacitor close to the
output pin and keep the leads short as possible.
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120 140 160 180 200
OUTPUT CURRENT (mA)
ESR (mW)
Figure 32. Minimal ESR of Output Ceramic
Capacitor vs. Output Current
V
out
= 0.9 V
V
in
= 3 V
FT Mode
T
A
= 25°C
C
out
= 1 mF
C
out
= 2.2 mF
0
50
100
150
200
250
300
0 20 40 60 80 100 120 140 160 180 200
OUTPUT CURRENT (mA)
Figure 33. Minimal ESR of Output Ceramic
Capacitor vs. Output Current
ESR (mW)
C
out
= 1 mF
C
out
= 2.2 mF
V
out
= 1.2 V
V
in
= 3 V
FT Mode
T
A
= 25°C
0
5
10
15
20
25
30
35
40
45
0 25 50 75 100 125 150 175 200
OUTPUT CURRENT (mA)
Figure 34. Minimal ESR of Output Ceramic
Capacitor vs. Output Current
ESR (mW)
V
out
= 3.3 V
V
in
= 5 V
FT Mode
T
A
= 25°C
C
out
= 1 mF
C
out
= 2.2 mF
