cs5203a-1 ON Semiconductor, cs5203a-1 Datasheet - Page 5

• Manufacturer Part Number: cs5203a-1
• Description: 3.0 A Adjustable, And Fixed 1.5 V, 3.3 V And 5.0 V Linear Regulators
• Manufacturer: ON Semiconductor

or adjustable voltages at currents up to 3.0 A. The regulators
are protected against short circuit, and include thermal
shutdown and safe area protection (SOA) circuitry. The
SOA protection circuitry decreases the maximum available
output current as the input−output differential voltage
increases.
transistor and requires an output capacitor for stability. A
detailed procedure for selecting this capacitor is included in
the Stability Considerations section.
Adjustable Operation
voltage range of 1.25 V to 13 V. An external resistor divider
sets the output voltage as shown in Figure 10. The regulator
maintains a fixed 1.25 V (typical) reference between the
output pin and the adjust pin.
current to flow to ground. This current creates a voltage
across R2 that adds to the 1.25 V across R1 and sets the
overall output voltage. The adjust pin current (typically
50 mA) also flows through R2 and adds a small error that
should be taken into account if precise adjustment of V
is necessary.
pin current.
10 mA. 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 CS5203A family of linear regulators provides fixed
The CS5203A has a composite PNP−NPN output
The adjustable regulator (CS5203A−1) has an output
A resistor divider network R1 and R2 causes a fixed
The output voltage is set according to the formula:
The term I
R1 is chosen so that the minimum load current is at least
V OUT + V REF
Adj
R2 represents the error added by the adjust
CS5203A−1, CS5203A−2, CS5203A−3, CS5203A−5
R1 ) R2
R1
100
90
80
70
60
50
40
30
20
10
0
10
) I Adj
1
Figure 9. Ripple Rejection vs. Frequency
APPLICATIONS INFORMATION
T
I
(V
V
C
OUT
CASE
RIPPLE
Adj
IN
− V
R2
= 25 mF
= 3.0 A
= 25 C
10
OUT
= 1.6 V
http://onsemi.com
(Adjustable Versions)
2
) = 3.0 V
OUT
Frequency (Hz)
PP
5
10
Stability Considerations
three main characteristics of a linear regulator: satrtup delay,
load transient response and loop stability.
size and temperature constraints. A tantalum or aluminum
electrolytic capacitor is best, since a film or ceramic
capacitor with almost zero ESR, can cause instability. The
aluminum electrolytic capacitor is the least expensive
solution. However, when the circuit operates at low
temperatures, both the value and ESR of the capacitor will
vary considerably. The capacitor manufacturers data sheet
provides this information.
applications, but with high current regulators such as the
CS5203A the transient response and stability improve with
higher values of capacitor. The majority of applications for
this regulator involve large changes in load current so the
output capacitor must supply the instantaneous load current.
3
V
IN
The output or compensation capacitor helps determine
The capacitor value and type is based on cost, availability,
A 22 mF tantalum capacitor will work for most
C
1
Figure 10. Resistor Divider Scheme for the
10
4
V
IN
CS5203A−1
Adjustable Version
Adj
10
5
C
V
Adj
OUT
I
Adj
V
REF
R
R
1
2
C
2
V
OUT