CS5201−3
1.0 A, 3.3 V Fixed Linear
Regulator
The CS5201−3 linear regulator provides 1.0 A @ 3.3 V reference at
1.0 A with an output voltage accuracy of
±1.5%.
This regulator is intended for use as a post regulator and
microprocessor supply. The fast loop response and low dropout
voltage make this regulator ideal for applications where low voltage
operation and good transient response are important.
The circuit is designed to operate with dropout voltages less than 1.2 V
at 1.0 A output current.
The maximum quiescent current is only 10 mA at full load. Device
protection includes overcurrent and thermal shutdown.
The CS5201−3 is pin compatible with the LT1086 family of linear
regulators.
The regulator is available in TO−220−3, surface mount D
2
, and
SOT−223 packages.
Features
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TO−220−3
T SUFFIX
CASE 221A
1
2
3
D
2
PAK−3
DP SUFFIX
CASE 418AB
Tab = V
OUT
Pin 1. GND
2. V
OUT
3. V
IN
•
•
•
•
•
•
Pb−Free Package is Available
Output Current to 1.0 A
Output Accuracy to
±1.5%
Overtemperature
Dropout Voltage (typical) 1.0 V @ 1.0 A
Fast Transient Response
Fault Protection
♦
Current Limit
♦
Thermal Shutdown
12
3
SOT−223
ST SUFFIX
CASE 318E
1
23
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 6 of this data sheet.
V
IN
V
OUT
DEVICE MARKING INFORMATION
3.3 V @ 1.0 A
See general marking information in the device marking
section on page 6 of this data sheet.
CS5201−3
GND
10
mF
5.0 V
22
mF
5.0 V
Figure 1. Applications Diagram
©
Semiconductor Components Industries, LLC, 2006
September, 2006
−
Rev. 8
1
Publication Order Number:
CS5201−3/D
CS5201−3
MAXIMUM RATINGS
Parameter
Supply Voltage, V
IN
Operating Temperature Range
Junction Temperature
Storage Temperature Range
Lead Temperature Soldering:
ESD Damage Threshold (Human Body Model)
Wave Solder (through hole styles only) (Note 1)
Reflow (SMD styles only) (Note 2)
Value
7.0
−40
to +70
150
−60
to +150
260 Peak
230 Peak
2.0
Unit
V
°C
°C
°C
°C
°C
kV
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. 10 second maximum.
2. 60 second maximum above 183°C.
ELECTRICAL CHARACTERISTICS
(C
IN
= 10
mF,
C
OUT
= 22
mF
Tantalum, V
OUT
+ V
DROPOUT
< V
IN
< 7.0 V, 0°C
≤
T
A
≤
70°C,
T
J
≤
+150°C, unless otherwise specified, I
full load
= 1.0 A)
Characteristic
Fixed Output Voltage
Reference Voltage (Notes 3 and 4)
Line Regulation
Load Regulation (Notes 3 and 4)
Dropout Voltage (Note 5)
Current Limit
Quiescent Current
Thermal Regulation (Note 6)
Ripple Rejection (Note 6)
Thermal Shutdown (Note 7)
Thermal Shutdown Hysteresis (Note 7)
V
IN
−
V
OUT
= 1.5 V;
0
≤
I
OUT
≤
1.0 A
2.0 V
≤
V
IN
−
V
OUT
≤
3.7 V; I
OUT
= 10 mA
V
IN
−
V
OUT
= 2.0 V; 10 mA
≤
I
OUT
≤
1.0 A
I
OUT
= 1.0 A
V
IN
−
V
OUT
= 3.0 V
I
OUT
= 10 mA
30 ms Pulse, T
A
= 25°C
f = 120 Hz; I
OUT
= 1.0 A; V
IN
−
V
OUT
= 3.0 V;
V
RIPPLE
= 1.0 V
PP
−
−
3.250
(−1.5%)
−
−
−
1.0
−
−
−
150
−
3.300
0.02
0.04
1.0
3.1
5.0
0.002
80
180
25
3.350
(+1.5%)
0.20
0.4
1.2
−
10
0.020
−
210
−
V
%
%
V
A
mA
%/W
dB
°C
°C
Test Conditions
Min
Typ
Max
Unit
3. Load regulation and output voltage are measured at a constant junction temperature by low duty cycle pulse testing. Changes in output
voltage due to temperature changes must be taken into account separately.
4. Specifications apply for an external Kelvin sense connection at a point on the output pin 1/4” from the bottom of the package.
5. Dropout voltage is a measurement of the minimum input/output differential at full load.
6. Guaranteed by design, not 100% tested in production.
7. Thermal shutdown is 100% functionally tested in production.
PACKAGE PIN DESCRIPTION
Package Pin Number
TO−220−3
1
2
3
D
2
PAK−3
1
2
3
SOT−223
1
2
3
Pin Symbol
GND
V
OUT
V
IN
Ground connection.
Regulated output voltage (case).
Input voltage.
Function
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2
CS5201−3
V
IN
V
OUT
Output
Current
Limit
Thermal
Shutdown
Bandgap
Reference
GND
−
+
Error
Amplifier
Figure 2. Block Diagram
TYPICAL PERFORMANCE CHARACTERISTICS
1.00
Output Voltage Deviation (%)
800
1000
0.10
T
CASE
= 0°C
T
CASE
= 25°C
0.08
0.06
0.04
0.02
0.00
−0.02
−0.04
−0.06
−0.08
−0.10
−0.12
0.95
V
DROPOUT
(V)
0.90
0.85
0.80
0.75
T
CASE
= 125°C
0
200
400
600
0
10 20 30 40 50 60 70 80 90 100 110 120 130
I
OUT
(mA)
T
J
(°C)
Figure 3. Dropout Voltage vs. Output
Current
0.100
Output Voltage Deviation (%)
85
75
Ripple Rejection (dB)
0.075
65
55
45
35
25
T
CASE
= 0°C
0
1
2
Figure 4. Reference Voltage vs.
Temperature
0.050
T
CASE
= 25°C
T
CASE
= 25°C
0.025
T
CASE
= 125°C
I
OUT
= 1.0 A
(V
IN
−
V
OUT
) = 3.0 V
V
RIPPLE
= 1.0 V
PP
0.000
15
10
1
10
2
10
3
10
4
10
5
10
6
Output Current (A)
Frequency (Hz)
Figure 5. Load Regulation vs. Output
Current
Figure 6. Ripple Rejection vs. Frequency
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CS5201−3
Voltage Deviation (mV)
300
200
100
0
I
SC
(A)
0
1
2
3
4
5
6
7
8
9
10
3.5
3.3
3.1
2.9
2.7
2.5
2.3
2.1
1.9
1.7
1.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
−100
−200
1000
500
0
Load Step (mA)
Time (mS)
C
OUT
= C
IN
= 22
mF
Tantalum
V
IN
−
V
OUT
(V)
Figure 7. Transient Response
Figure 8. Short Circuit Current vs.
V
IN
−
V
OUT
APPLICATIONS INFORMATION
The CS5201−3 linear regulator provides a fixed 3.3 V
output voltage at currents up to 1.0 A. The regulator is
protected against overcurrent conditions and includes
thermal shutdown.
The CS5201−3 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.
Stability Considerations
ceramic capacitors in parallel. This reduces the overall ESR
and reduces the instantaneous output voltage drop under
transient load conditions. The output capacitor network
should be as close to the load as possible for the best results.
Protection Diodes
The output compensation capacitor helps determine three
main characteristics of a linear regulator: startup delay, load
transient response, and loop stability.
The capacitor value and type is based on cost, availability,
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 manufacturer’s data sheet
provides this information.
A 22
mF
tantalum capacitor will work for most
applications, but with high current regulators such as the
CS5201−3 the transient response and stability improve with
higher values of capacitance. The majority of applications
for this regulator involve large changes in load current so the
output capacitor must supply the instantaneous load current.
The ESR of the output capacitor causes an immediate drop
in output voltage given by:
DV
+
DI
ESR
When large external capacitors are used with a linear
regulator it is sometimes necessary to add protection diodes.
If the input voltage of the regulator gets shorted, the output
capacitor will discharge into the output of the regulator. The
discharge current depends on the value of the capacitor, the
output voltage and the rate at which V
IN
drops. In the
CS5201−3 linear regulator, the discharge path is through a
large junction and protection diodes are not usually needed.
If the regulator is used with large values of output
capacitance and the input voltage is instantaneously shorted
to ground, damage can occur. In this case, a diode connected
as shown in Figure 9 is recommended.
IN4002 (Optional)
V
IN
C
1
V
OUT
V
IN
V
OUT
CS5201−3
GND
C
2
Figure 9. Protection Diode Scheme for Large
Output Capacitors
For microprocessor applications it is customary to use an
output capacitor network consisting of several tantalum and
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CS5201−3
Output Voltage Sensing
Since the CS5201−3 is a three terminal regulator, it is not
possible to provide true remote load sensing. Load
regulation is limited by the resistance of the conductors
connecting the regulator to the load. For best results the
regulator should be connected as shown in Figure 10.
R
C
Conductor Parasitic
Resistance
The maximum power dissipation for a regulator is:
PD(max)
+
{VIN(max)
*
VOUT(min)}IOUT(max)
)
VIN(max)IQ
(2)
V
IN
V
IN
V
OUT
CS5201−3
R
LOAD
where:
V
IN(max)
is the maximum input voltage,
V
OUT(min)
is the minimum output voltage,
I
OUT(max)
is the maximum output current, for the
application
I
Q
is the maximum quiescent current at I
OUT(max)
.
A heatsink effectively increases the surface area of the
package to improve the flow of heat away from the IC and
into the surrounding air.
Each material in the heat flow path between the IC and the
outside environment has a thermal resistance. Like series
electrical resistances, these resistances are summed to
determine R
qJA
, the total thermal resistance between the
junction and the surrounding air.
1. Thermal Resistance of the junction−to−case, R
qJC
(°C/W)
2. Thermal Resistance of the case to heatsink, R
qCS
(°C/W)
3. Thermal Resistance of the heatsink to the ambient air,
R
qSA
(°C/W)
These are connected by the equation:
R
qJA
+
R
qJC
)
R
qCS
)
R
qSA
(3)
Figure 10. Conductor Parasitic Resistance Effects
Can Be Minimized With the Above Grounding
Scheme For Fixed Output Regulators
Calculating Power Dissipation and Heatsink
Requirements
The CS5201−3 linear regulator includes thermal
shutdown and current limit circuitry to protect the device.
High power regulators such as these usually operate at high
junction temperatures so it is important to calculate the
power dissipation and junction temperatures accurately to
ensure that an adequate heatsink is used.
The case is connected to V
OUT
on the CS5201−3,
electrical isolation may be required for some applications.
Thermal compound should always be used with high current
regulators such as these.
The thermal characteristics of an IC depend on the
following four factors:
1.
2.
3.
4.
Maximum Ambient Temperature T
A
(°C)
Power dissipation P
D
(Watts)
Maximum junction temperature T
J
(°C)
Thermal resistance junction to ambient R
qJA
(°C/W)
These four are related by the equation
TJ
+
TA
)
P D
R
qJA
(1)
The maximum ambient temperature and the power
dissipation are determined by the design while the
maximum junction temperature and the thermal resistance
depend on the manufacturer and the package type.
The value for R
qJA
is calculated using equation (3) and the
result can be substituted in equation (1).
The value for R
qJC
is 3.5°C/W for a given package type
based on an average die size. For a high current regulator
such as the CS5201−3 the majority of the heat is generated
in the power transistor section. The value for R
qSA
depends
on the heatsink type, while R
qCS
depends on factors such as
package type, heatsink interface (is an insulator and thermal
grease used?), and the contact area between the heatsink and
the package. Once these calculations are complete, the
maximum permissible value of R
qJA
can be calculated and
the proper heatsink selected. For further discussion on
heatsink selection, see application note “Thermal
Management,” document number AND8036/D, available
through the Literature Distribution Center or via our website
at http://onsemi.com.
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