CS5205-1,-3,-5
Typical Performance Characteristics: continued
70.0
I
O
= 10mA
Ripple Rejection (dB)
65.0
Adjust Pin Current (mA)
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
60.0
55.0
50.0
T
CASE
= 25°C
I
OUT
= 5A
(V
IN
Ð V
OUT
) = 3V
V
RIPPLE
= 1.6V
PP
45.0
10.0
40.0
0
10
20
30
40
50
60
70
80
90 100 110 120 130
Temperature (°C)
0.0
10
1
10
2
10
3
Frequency (Hz)
10
4
10
5
Adjust Pin Current vs. Temperature
Ripple Rejection vs. Frequency (Fixed Versions)
100.0
90.0
Ripple Rejection (dB)
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
10
1
10
2
10
3
Frequency (Hz)
10
4
10
5
T
CASE
= 25°C
I
OUT
= 5A
(V
IN
Ð V
OUT
) = 3V
V
RIPPLE
= 1.6V
PP
C
Adj
= 25mF
Ripple Rejection vs. Frequency (Adjustable Version)
Applications Information
The CS5205-X family of linear regulators provide fixed or
adjustable voltages at currents up to 5A. The regulators
are protected against short circuit, and include thermal
shutdown and safe area protection (SOA) circuitry. The
SOA protection circuitry decreases the maximum avail-
able output current as the input-output differential volt-
age increases.
The CS5205-X has a composite PNP-NPN output transistor
and requires an output capacitor for stability. A detailed
procedure for selecting this capacitor is included in the
Stability Considerations section.
Adjustable Operation
The output voltage is set according to the formula:
V
OUT
= V
REF
´
R1 + R2 + I
Adj
´
R2
R1
The term I
Adj
´
R2 represents the error added by the adjust
pin current.
R1 is chosen so that the minimum load current is at least
10mA. R1 and R2 should be the same type, e.g. metal film
for best tracking over temperature. The adjust pin is
bypassed to improve the transient response and ripple
rejection of the regulator.
(
)
The adjustable regulator (CS5205-1) has an output voltage
range of 1.25V to 13V. An external resistor divider sets the
output voltage as shown in Figure 1. The regulator main-
tains a fixed 1.25V (typical) reference between the output
pin and the adjust pin.
A resistor divider network R1 and R2 causes a fixed cur-
rent to flow to ground. This current creates a voltage
across R2 that adds to the 1.25V across R1 and sets the
overall output voltage. The adjust pin current (typically
50µA) also flows through R2 and adds a small error that
should be taken into account if precise adjustment of V
OUT
is necessary.
4
V
IN
C
1
V
IN
V
OUT
V
OUT
V
REF
R
1
C
2
CS5205-1
Adj
I
Adj
C
Adj
R
2
Figure 1. Resistor divider scheme for the adjustable version.
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
