1
Features
5V
CS5201-1
VIN
Adj
200W
1%
10mF
5V
0.1mF
5V Tant
3.3V @ 1A
22mF
5V
124W
1%
VOUT
Output Current to 1A
Output Accuracy to ±1%
over Temperature
Dropout Voltage (typical)
1.0V @ 1A
Fast Transient Response
Fault Protection
Current Limit
Thermal Shutdown
Package Options
3L TO-220
Tab (VOUT)
CS5201-1
1A Adjustable Linear Regulator
1
CS5201-1
Application Diagram
CS5201 -1
1 Adj
2V
OUT(Tab)
3V
IN
Description
3L D2PAK
Tab (VOUT)
1
Consult factory for fixed output
voltage versions.
The CS5201-1 linear regulator
provides 1A with an output
voltage accuracy of ±1%. The
device uses two external resis-
tors to set the output voltage
within a 1.25V to 5.5V range.
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 impor-
tant.
The circuit is designed to oper-
ate with dropout voltages less
than 1.2V at 1A output current.
Device protection includes over-
current and thermal shutdown.
The CS5201 is pin compatible
with the LT1086 family of linear
regulators.
The regulator is available in
TO-220, surface mount D2, and
SOT-223 packages.
A Company
¨
1
3L SOT-223
Tab (VOUT)
Rev. 2/16/98
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
D2PAK TO-220 SOT-223
1 1 1 Adj Adjust pin (low side of the internal reference).
22 2 V
OUT Regulated output voltage (case).
33 3 V
IN Input voltage.
CS5201-1
Package Pin Description
PACKAGE PIN # PIN SYMBOL FUNCTION
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Electrical Characteristics: CIN = 10µF, COUT = 22µF Tantalum, VOUT + VDROPOUT < VIN < 7V, 0¡C ² TA ² 70¡C, TJ² +150¡C,
unless otherwise specified, Ifull load = 1A.
2
Adjustable Output Voltage
Reference Voltage VINÐVOUT=1.5V; VAdj = 0V 1.241 1.254 1.266 V
(Notes 1 and 2) 10mA²IOUT²1A (-1%) (+1%)
Line Regulation 1.5V²VINÐVOUT²5.75V; IOUT=10mA 0.02 0.20 %
Load Regulation VINÐVOUT=1.5V; 10mA²IOUT²1A 0.04 0.4 %
(Notes 1 and 2)
Dropout Voltage (Note 3) IOUT=1A 1.0 1.2 V
Current Limit VINÐVOUT=3V; TJ³ 25¡C 1.1 3.1 A
Minimum Load Current (Note 4) VIN=7V ; VAdj=0 0.6 2.0 mA
Adjust Pin Current VINÐVOUT=3V; IOUT=10mA 50 100 µA
Thermal Regulation (Note 5) 30ms pulse; TA=25¡C 0.002 0.020 %/W
Ripple Rejection (Note 5) f=120Hz; IOUT=1A; VINÐVOUT=3V; 80 dB
VRIPPLE=1VPP
Thermal Shutdown (Note 6) 150 180 210 ¡C
Thermal Shutdown Hysteresis 25 ¡C
(Note 6)
Note 1: 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.
Note 2: Specifications apply for an external Kelvin sense connection at a point on the output pin 1/4Ó from the bottom of the package.
Note 3: Dropout voltage is a measurement of the minimum input/output differential at full load.
Note 4: The minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor divider used
to set the output voltage is selected to meet the minimum load requirement.
Note 5: Guaranteed by design, not 100% tested in production.
Note 6: Thermal shutdown is 100% functionally tested in production.
Absolute Maximum Ratings
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7V
Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40¡C to 70¡C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150¡C
Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-60¡C to 150¡C
Lead Temperature Soldering
Wave Solder (through hole styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 sec. max, 260¡C peak
Reflow (SMD styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 sec. max above 183¡C, 230¡C peak
ESD Damage Threshold (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV
CS5201-1
3
Typical Performance Characteristics
VDropout (V)
IOUT (mA)
0.90
0.75
0.85
0.95
1.00
0.80
0200 400 600 800 1000
TCASE = 0°C
TCASE = 25°C
TCASE = 125°C
0 10 130
-0.12
0.10
Output Voltage Deviation (%)
TJ (°C)
20 30 40 50 60 70 80 90 100 110 120
0.08
0.06
0.04
0.02
0.00
-0.02
-0.04
-0.06
-0.08
-0.10
0.025
0.000
0.050
0.075
0.100
012
Output Current (A)
Output Voltage Deviation (%)
TCASE = 0°C
TCASE = 125°C
TCASE = 25°C
Dropout Voltage vs. Output Current Reference Voltage vs. Temperature
Load Regulation vs. Output Current
123456
0.40
Minimum Load Current (mA)
VIN – VOUT (V) 7
0.45
0.50
0.55
0.60
0.65
TCASE = 0°C
TCASE = 125°C
TCASE = 25°C
CIN =COUT =22mF Tantalum
Minimum Load Current vs VIN-VOUT
Block Diagram
Error
Amplifier
Output
Current
Limit
VIN
VOUT
Thermal
Shutdown
Bandgap
Reference
Adj
+-
4
CS5201-1
Applications Information
The CS5201-1 linear regulator provides adjustable volt-
ages at currents up to 1A. The regulator is protected
against overcurrent conditions and includes thermal
shutdown.
The CS5201-1 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.
The CS5201-1 has an output voltage range of 1.25V to 5.5V.
An external resistor divider sets the output voltage as
shown in Figure 1. The regulator maintains 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 VOUT
is necessary.
The output voltage is set according to the formula:
VOUT = VREF ´
()
+ IAdj ´R2
The term IAdj ´R2 represents the error added by the adjust
pin current.
R1is chosen so that the minimum load current is at least
2mA. R1 and R2 should be the same type, e.g. metal film
for best tracking over temperature. While not required, a
bypass capacitor from the adjust pin to ground will
improve ripple rejection and transient response. A 0.1µF
tantalum capacitor is recommended for Òfirst cutÓ design.
Type and value may be varied to obtain optimum perfor-
mance vs. price.
R1 + R2
R1
Adjustable Operation
02030405060
40.0
Adjust Pin Current (mA)
Temperature (°C)
80
45.0
50.0
55.0
60.0
65.0
70.0
90 100
10 70 110 120 130
IO = 10mA
Adjust Pin Current vs. Temperature
15
101
Frequency (Hz)
Ripple Rejection (dB)
25
35
45
55
65
75
85
102103104105106
TCASE = 25°C
IOUT = 1A
(VIN Ð VOUT) = 3V
VRIPPLE = 1.0VPP
CAdj = 0.1mF
Ripple Rejection vs. Frequency
023456
500
Voltage Deviation (mV)
7
-100
0
100
200
Time mS
Load Step (mA)
10981
1000
-200
0
VOUT = 3.3V
COUT= CIN = 22mF Tantalum
CAdj= 0.1mF
Transient Response
Typical Performance Characteristics: continued
1.5 2.5 3.0 3.5
1.5
ISC(A)
VIN - VOUT (V)
1.7
1.9
2.1
2.3
3.1
3.3
1.0 4.0
2.5
2.7
2.9
3.5
2.0
Short Circuit Current vs. VIN - VOUT
5
Applications Information: continued
CS5201-1
Figure 1. Resistor divider scheme.
The CS5201-1 linear regulator has an absolute maximum
specification of 7V for the voltage difference between VIN
and VOUT. However, the IC may be used to regulate volt-
ages in excess of 7V. The main considerations in such a
design are power-up and short circuit capability.
In most applications, ramp-up of the power supply to VIN
is fairly slow, typically on the order of several tens of mil-
liseconds, while the regulator responds in less than one
microsecond. In this case, the linear regulator begins
charging the load as soon as the VIN to VOUT differential is
large enough that the pass transistor conducts current. The
load at this point is essentially at ground, and the supply
voltage is on the order of several hundred millivolts, with
the result that the pass transistor is in dropout. As the sup-
ply to VIN increases, the pass transistor will remain in
dropout, and current is passed to the load until VOUT
reaches the point at which the IC is in regulation. Further
increase in the supply voltage brings the pass transistor
out of dropout. The result is that the output voltage fol-
lows the power supply ramp-up, staying in dropout until
the regulation point is reached. In this manner, any output
voltage may be regulated. There is no theoretical limit to
the regulated voltage as long as the VIN to VOUT differen-
tial of 7V is not exceeded.
However, the possibility of destroying the IC in a short
circuit condition is very real for this type of design. Short
circuit conditions will result in the immediate operation of
the pass transistor outside of its safe operating area. Over-
voltage stresses will then cause destruction of the pass
transistor before overcurrent or thermal shutdown circuit-
ry can become active. Additional circuitry may be required
to clamp the VIN to VOUT differential to less than 7V if fail-
safe operation is required. One possible clamp circuit is
illustrated in figure 2; however, the design of clamp cir-
cuitry must be done on an application by application basis.
Care must be taken to ensure the clamp actually protects
the design. Components used in the clamp design must be
able to withstand the short circuit condition indefinitely
while protecting the IC.
Figure 2. Short Circuit Protection Circuit for High Voltage Application.
The output or compensation capacitor helps determine
three main characteristics of a linear regulator: start-up
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 capaci-
tor with almost zero ESR can cause instability. The alu-
minum electrolytic capacitor is the least expensive solu-
tion. However, when the circuit operates at low tempera-
tures, both the value and ESR of the capacitor will vary
considerably. The capacitor manufacturersÕ data sheet pro-
vides this information.
A 22µF tantalum capacitor will work for most applications,
but with high current regulators such as the CS5201 the
transient response and stability improve with higher val-
ues of capacitance. The majority of applications for this
regulator involve large changes in load current so the out-
put capacitor must supply the instantaneous load current.
The ESR of the output capacitor causes an immediate drop
in output voltage given by:
ÆV = ÆI ´ESR
For microprocessor applications it is customary to use an
output capacitor network consisting of several tantalum and
ceramic capacitors in parallel. This reduces the overall ESR
and reduces the instantaneous output voltage drop under
load transient conditions. The output capacitor network
should be as close as possible to the load for the best results.
When large external capacitors are used with a linear regu-
lator 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 capaci-
tor, the output voltage and the rate at which VIN drops. In
the CS5201-1 linear regulator, the discharge path is
through a large junction and protection diodes are not usu-
ally needed. If the regulator is used with large values of
output capacitance and the input voltage is instantaneous-
ly shorted to ground, damage can occur. In this case, a
diode connected as shown in Figure 3 is recommended.
Protection Diodes
Stability Considerations
VIN VOUT
VAdj
EXTERNAL SUPPLY
VOUT
Short Circuit Protection
VOUT
VIN
CS5201-1
VIN
Adj
R1
R2
C1
CAdj
VOUT
C2
VREF
IAdj
Figure 3. Protection diode for large output capacitors.
Since the CS5201-1 is a three terminal regulator, it is not
possible to provide true remote load sensing. Load regula-
tion is limited by the resistance of the conductors connect-
ing the regulator to the load.
For the adjustable regulator, the best load regulation
occurs when R1 is connected directly to the output pin of
the regulator as shown in Figure 4. If R1 is connected to the
load, RCis multiplied by the divider ratio and the effective
resistance between the regulator and the load becomes
RC´
()
RC= conductor parasitic resistance
Figure 4. Grounding scheme for the adjustable output regulator to min-
imize parasitic resistance effects.
The CS5201-1 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 heat sink is used.
The case is connected to VOUT on the CS5201-1, and electri-
cal isolation may be required for some applications.
Thermal compound should always be used with high cur-
rent regulators such as these.
The thermal characteristics of an IC depend on the follow-
ing four factors:
1. Maximum Ambient Temperature TA (¡C)
2. Power dissipation PD (Watts)
3. Maximum junction temperature TJ (¡C)
4. Thermal resistance junction to ambient RQJA (C/W)
These four are related by the equation
TJ= TA+ PD´RQJA (1)
The maximum ambient temperature and the power dissi-
pation are determined by the design while the maximum
junction temperature and the thermal resistance depend
on the manufacturer and the package type.
The maximum power dissipation for a regulator is:
PD(max)={VIN(max)ÐVOUT(min)}IOUT(max)+VIN(max)IQ(2)
where
VIN(max) is the maximum input voltage,
VOUT(min) is the minimum output voltage,
IOUT(max) is the maximum output current, for the application
IQis the maximum quiescent current at IOUT(max).
A heat sink 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 RQJA, the total thermal resistance between the
junction and the surrounding air.
1. Thermal Resistance of the junction to case, RQJC (¡C/W)
2. Thermal Resistance of the case to Heat Sink, RQCS (¡C/W)
3. Thermal Resistance of the Heat Sink to the ambient air,
RQSA (¡C/W)
These are connected by the equation:
RQJA = RQJC + RQCS + RQSA (3)
The value for RQJA is calculated using equation (3) and the
result can be substituted in equation (1).
The value for RQJC is 3.5ûC/W for a given package type
based on an average die size. For a high current regulator
such as the CS5201-1 the majority of the heat is generated
in the power transistor section. The value for RQSA
depends on the heat sink type, while RQCS depends on fac-
tors such as package type, heat sink interface (is an insula-
tor and thermal grease used?), and the contact area
between the heat sink and the package. Once these calcula-
tions are complete, the maximum permissible value of
RQJA can be calculated and the proper heat sink selected.
For further discussion on heat sink selection, see applica-
tion note ÒThermal Management for Linear Regulators.Ó
Calculating Power Dissipation and Heat Sink Requirements
VOUT
RC
VIN
conductor parasitic
resistance
CS5201-1
VIN
Adj
RLOAD
R1
R2
R1 + R2
R1
Output Voltage Sensing
VOUT
VIN
CS5201-1
VIN
Adj
R1
R2
C1
VOUT
C2
CAdj
IN4002 (optional)
6
CS5201-1
Applications Information: continued
Part Number Type Description
CS5201-1GT3 1A, adj. output 3 L TO-220 Straight
CS5201-1GDP3 1A, adj. output 3 L D2PAK
CS5201-1GDPR3 1A, adj. output 3 L D2PAK (tape & reel)
CS5201-1GST3 1A, adj. output 3 L SOT-223
CS5201-1GSTR3 1A, adj. output 3 L SOT-223 (tape & reel)
7
CS5201-1
Ordering Information
Rev. 2/16/98
Cherry Semiconductor Corporation reserves the right to
make changes to the specifications without notice. Please
contact Cherry Semiconductor Corporation for the latest
available information.
Package Specification
3L 3L 3L
Thermal Data TO-220 D2PAK SOT-223
RQJC typ 3.5 3.5 15 ûC/W
RQJA typ 50 10 - 50* 156 ûC/W
*Depending on thermal properties of substrate. RQJA = RQJC + RQCA
PACKAGE THERMAL DATA
© 1999 Cherry Semiconductor Corporation
PACKAGE DIMENSIONS IN mm (INCHES)
3 Lead D2PAK (DP)
2.54 (.100) REF
10.31 (.406)
10.05 (.396)
8.53 (.336)
8.28 (.326)
0.91 (.036)
0.66 (.026)
1.40 (.055)
1.14 (.045)
4.57 (.180)
4.31 (.170)
1.68 (.066)
1.40 (.055)
2.74(.108)
2.49(.098)
1.40 (.055)
1.14 (.045)
0.10 (.004)
0.00 (.000)
.254 (.010) REF
15.75 (.620)
14.73 (.580)
2.79 (.110)
2.29 (.090)
3 Lead TO-220 (T) Straight
5.33 (.210)
4.83 (.190)
2.79 (.110)
2.29 (.090)
1.02 (.040)
0.63 (.025)
0.56 (.022)
0.38 (.014)
1.40 (.055)
1.14 (.045)
4.83 (.190)
4.06 (.160)
6.17 (.243) REF
1.14 (.045)
1.52 (.060)
1.14 (.045)
1.40 (.055)
2.87 (.113)
2.62 (.103)
6.55 (.258)
5.94 (.234)
14.22 (.560)
13.72 (.540)
2.92 (.115)
2.29 (.090)
9.78 (.385)
10.54 (.415)
3.71 (.146)
3.96 (.156)
14.99 (.590)
14.22 (.560)
3 Lead SOT-223 (ST)
10° MAX
1.30 (.051)
1.10 (.043)
4.60 (.181)
2.30 (.090)
1.05 (.041)
0.85 (.033)
7.30 (.287)
6.70 (.264)
3.30 (.130)
3.70 (.146)
3.15 (.124)
2.95 (.116)
6.70 (.264)
6.30 (.248)
1.70 (.067)
1.50 (.060)
0.10 (.004)
0.02 (.001)
0.85 (.033)
0.65 (.026)
0.35 (.014)
0.25 (.010)