Features
V
IN
CS5210-1
3.3V@10A
300
mF
Load
200
124
0.1
mF
100
mF
5.0V
Adj
V
OUT
s
1.25V to 4.5V V
OUT
at 10A
s
Dropout Voltage < 1.05V @ 10A
s
2% Trimmed Reference
s
Fast Transient Response
s
Thermal Shutdown
s
Current Limit
s
Short Circuit Protection
Package Options
CS5210-1
10A LDO 3-Pin Adjustable Linear Regulator
CS5210-1
Description
The CS5210-1 linear regulator pro-
vides 10A at adjustable voltages
from 1.25V to 4.5V. This adjustable
device requires two external resis-
tors to set the output voltage and
provide the minimum load current
for proper regulation.
This regulator is intended for use as
a post regulator and microprocessor
supply. The fast loop response and
low dropout voltage make this reg-
ulator ideal for applications where
low voltage operation and good
transient response are important.
The circuit is designed to operate
with dropout voltages as low as
1.05V at 10A.
The regulator is protected against
overload conditions with overcur-
rent and thermal shutdown protec-
tion circuitry.
The regulator is available in a
TO-220 package.
Applications Diagram
1
3 Lead TO-220
1
1. Adjust
2. V
OUT
3. V
IN
Tab = V
OUT
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
A Company
Rev. 6/12/97
Electrical Characteristics: 0CT
A
70C, 0CT
J
150C, V
Adj
= 0V unless otherwise specified.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CS5210-1
2
Absolute Maximum Ratings
Input Voltage ............................................................................................................................................................................6V
Operating Ambient Temperature Range.......................................................................................................0C T
A
70C
Operating Junction Temperature Range.......................................................................................................0C T
J
150C
Storage Temperature Range ............................................................................................................................-65C to +150C
Lead Temperature Soldering
Wave Solder (through hole styles only) .................................................................................10 sec. max, 260C peak
ESD Damage Threshold ........................................................................................................................................................2kV
Reference voltage
V
IN
=2.75V to 5.5V, I
OUT
=10mA to 10A
1.227
1.253
1.278
V
(-2%)
(+2%)
Line Regulation
V
IN
=2.75V to 5.5V, I
OUT
=10mA
.02
.20
%
Load Regulation
V
IN
=2.75V,I
OUT
=10mA to 10A
.04
.50
%
Minimum Load Current
V
IN
=5V, V
OUT
= +2%
5
10
mA
(Note 1)
Adjust Pin Current
V
IN
=2.75V,I
OUT
=10mA
70
120
A
Current Limit
V
IN
=2.75V,V
OUT
= -2%
10.1
12.0
A
Short Circuit Current
V
IN
=2.75V,V
OUT
=0V
8.0
10.0
A
Ripple Rejection
V
IN
=3.25V Avg,
60
80
dB
(Note 2)
V
Ripple
=1V
P-P
@120Hz,
I
OUT
=4A,C
Adj
=0.1F, C
OUT
=22F
Thermal Regulation
30ms Pulse, T
A
=25C 0.002
%/W
(Note 2)
Dropout Voltage
I
OUT
=100mA
0.92
1.15
V
(Minimum V
IN
-V
OUT
)
I
OUT
=1A
0.93
1.15
V
(Note 3)
I
OUT
=2.75A
0.94
1.15
V
I
OUT
=4A
0.95
1.15
V
I
OUT
=10A
1.03
1.40
V
RMS Output Noise
Freq=10Hz to 10kHz, T
A
=25C
0.003
%V
OUT
Temperature Stability
0.5
%
Thermal Shutdown
150
180
210
C
(Note 4)
Thermal Shutdown Hysteresis
25
C
(Note 4)
Note 1: 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 current requirement.
Note 2: This parameter is guaranteed by design and is not 100% production tested.
Note 3: Dropout voltage is defined as the minimum input/output voltage differential required to maintain 2% regulation.
Note 4: This parameter is guaranteed by design, but not parametrically tested in production. However, a 100% thermal shutdown functional test is
performed on each part.
CS5210-1
3
Typical Performance Characteristics
Package Pin Description
PACKAGE PIN #
PIN SYMBOL
FUNCTION
3L TO-220
1
Adjust
This pin is connected to the low side of the internally trimmed
2% bandgap reference voltage and carries a bias current of
about 70A. A resistor divider from Adj to V
OUT
and from Adj
to ground sets the output voltage. Also, transient response can
be improved by adding a small bypass capacitor from this pin
to ground.
2
V
OUT
This pin is connected to the emitter of the power pass transistor
and provides a regulated voltage capable of sourcing 10A of
current.
3
V
IN
This is the supply voltage for the regulator. For the device to
regulate, this voltage should be between 1.2V and 1.40V
(depending on the output current) greater than the output
voltage.
Block Diagram
V
IN
BIAS
and
TSD
V
REF
EA
IA
V
OUT
Adj
-
+
-
+
0.00
71.00
73.00
Adjust Pin Current (uA)
I
OUT
(A)
2.00
3.00 4.00 5.00
72.80
72.60
72.40
72.20
72.00
71.80
71.60
71.40
71.20
70.80
70.60
70.40
70.20
70.00
1.00
6.00
8.00
10.00
7.00
9.00
Adjust Pin Current vs I
OUT
0
10 20 30 40 50 60 70 80 90 100 110120130
60.00
65.00
70.00
75.00
80.00
85.00
90.00
T
Case
(
C)
ADJUST
PIN CURRENT
(
m
A)
I
0
=10mA
Adjust Pin Current Voltage vs Temperature
0
10 20 30 40 50 60 70 80 90 100 110120130
-0.150
-0.125
-0.100
-0.075
-0.050
-0.025
-0.000
0.025
0.050
0.075
0.100
T
J
(
C)
OUTPUT
VOL
T
AGE DEVIA
TION (%)
I
0
=10mA
V
IN
=2.75V
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.00
0.000
0.050
0.150
0.200
0.300
OUTPUT CURRENT (A)
OUTPUT
VOL
T
AGE DEVIA
TION (%)
0.350
0.250
0.100
T
Case
=0
C
T
Case
=25
C
T
Case
=125
C
Load Regulation vs Output Current
Reference Voltage vs Temperature
CS5210-1
4
0
2.0
4.0
6.0
8.0
0.000
0.250
Output Current (A)
V
DROPOUT
(mV)
10
0.500
0.750
1.000
1.250
1.0
3.0
5.0
7.0
9.0
0.0
0.5
5.5
0.0
20.0
Output Current (A)
V
IN
-V
OUT
(V)
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
50
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
Il
min
vs V
IN
- V
OUT
VDropout vs I
OUT
1.00
0.80
1.00
Minimum Load Current (mA)
V
IN
-V
OUT
(V)
2.00
3.00
4.00
5.00
0.98
0.96
0.94
0.92
0.90
0.88
0.86
0.84
0.82
T
CASE
=23C
T
CASE
=125C
T
CASE
=0C
Minimum Load Current vs V
IN
-V
OUT
10.0
10
1
Frequency (Hz)
Ripple Rejection (dB)
20.0
30.0
40.00
60.0
70.0
80.0
90.0
10
2
10
3
10
4
10
6
10
5
50.0
V
IN
-V
OUT
=2V
I
OUT
=4A
V
RIPPLE
=1V
P-P
C
OUT
=22
mF
C
ADJ
=0.1
mF
Ripple Rejection vs Frequency
Typical Performance Characteristics: continued
CS5210-1
Application Notes: continued
5
The CS5210-1 linear regulator has a composite PNP-NPN
output stage that requires an output capacitor for stability.
A detailed procedure for selecting this capacitor is includ-
ed in the Stability Considerations section.
Design Guidelines
This LDO adjustable regulator has an output voltage range
of 1.25V to 4.5V. An external resistor divider sets the out-
put voltage as shown in Figure 1. The regulators voltage
sensing error amplifier maintains a fixed 1.25V reference
between the output pin and the adjust pin.
A resistor divider network R
1
and R
2
causes a fixed current
to flow to ground. This current creates a voltage across R
2
that adds to the 1.25V across R
1
and sets the overall output
voltage. The adjust pin current (typically 50A) also flows
through R
2
and adds a small error that should be taken
into account if precise adjustment of V
OUT
is necessary.
The output voltage is set according to the formula:
V
OUT
= V
REF
+ R
2
I
Adj
The term I
Adj
R
2
represents the error added by the adjust
pin current.
R
1
is chosen so that the minimum load current is a least
10mA. R
1
and R
2
should be of the same composition for
best tracking over temperature. The divider resistor
should be placed as close to the IC as possible and connect-
ed to the output with a separate metal trace.
Figure 1:
While not required, a bypass capacitor connected between
the adjust pin and ground will improve transient response
and ripple rejection. A 0.1F tantalum capacitor is recom-
mended for first cut design. Value and type may be var-
ied to optimize performance vs price.
The CS5210-1 linear regulator has an absolute maximum
specification of 6V for the voltage difference between V
IN
and V
OUT
. However, the IC may be used to regulate volt-
ages in excess of 6V. The main considerations in such a
design are power-up and short circuit capability.
In most applications, ramp-up of the power supply to V
IN
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 output capacitor as soon as the V
IN
to V
OUT
differential is large enough that the pass transistor con-
ducts current. V
OUT
is essentially at ground, and V
IN
is on
the order of several hundred millivolts, so that the pass
transistor is in dropout. As V
IN
increases, the pass transis-
tor will remain in dropout, and current is passed to the
load until V
OUT
is in regulation. Further increase in V
IN
brings the pass transistor out of dropout. The result is that
the output voltage follows 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 V
IN
to V
OUT
differential of 6V is not exceeded.
However, maximum ratings of the IC will be exceeded in a
short circuit condition. 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 circuitry can become active.
Additional circuitry may be required to clamp V
IN
to V
OUT
differential to less than 6V if failsafe operation is required.
One possible clamp circuit is illustrated below; however,
the design of clamp circuitry must be done on an applica-
tion 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 cir-
cuit conditions indefinitely while protecting the IC.
Figure 2:
V
IN
V
OUT
V
Adj
EXTERNAL SUPPLY
V
IN
CS5210-1
R1
Adj
R2
V
OUT
R
1
+ R
2
R
1
Adjustable Operation
Theory of Operation
CS5210-1
6
The output 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 solution.
However, when the circuit operates at low temperatures,
both the value and ESR of the capacitor will vary consider-
ably. The capacitor manufacturers data sheet provides this
information.
A 300F tantalum capacitor will work for most applica-
tions, but with high current regulators such as the CS5210
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 out-
put capacitor must supply the instantaneous load current.
The ESR of the output capacitor causes an immediate drop
in output voltage given by:
V = I
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
transient load conditions. The output capacitor network
should be as close to the load as possible for the best results.
Protection Diodes
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 V
IN
drops. In
the CS5210-1 regulator, the discharge path is through a
large junction and protection diodes are not usually need-
ed. If the regulator is used with large values of output
capacitance and the input voltage is instantaneously short-
ed to ground, damage can occur. In this case, a diode con-
nected as shown in Figure 3 is recommended.
A rule of thumb useful in determining if a protection diode
is required is to solve for current
I=
, where
I
is the current flow out of the load capacitance
when V
IN
is shorted,
C
is the value of load capacitance
V
is the output voltage, and
T
is the time duration required for V
IN
to transition
from high to being shorted.
If the calculated current is greater than or equal to the typi-
cal short circuit current valued provided in the specifica-
tions, serious thought should be given to include a protec-
tion diode.
Figure 3:
Current Limit
The internal current limit circuit limits the output current
under excessive load conditions and protects the regulator.
Short Circuit Protection
The device includes foldback short circuit current limit that
clamps the output current at approximately two amperes
less than its current limit value.
Thermal Shutdown
The thermal shutdown circuitry is guaranteed by design to
become activated above a die junction temperature of
150C and to shut down the regulator output. This circuit-
ry includes a thermal hysteresis circuit with 25C of typical
hysteresis, thereby allowing the regulator to recover from a
thermal fault automatically.
Calculating Power Dissipation and Heat Sink
Requirements
High power regulators such as the CS5210-1 usually oper-
ate at high junction temperatures. Therefore, it is important
to calculate the power dissipation and junction tempera-
tures accurately to ensure that an adequate heat sink is
used. Since the package tab is connected to Vout on the
CS5210-1, electrical isolation may be required for some
applications. Also, as with all high power packages, ther-
mal compound in necessary to ensure proper heat flow.
For added safety, this high current LDO includes an inter-
nal thermal shutdown circuit.
The thermal characteristics of an IC depend on the follow-
ing four factors. Junction temperature, ambient tempera-
ture, die power dissipation, and the thermal resistance
V
IN
CS5210-1
Adj
V
OUT
C
V
T
Stability Considerations
Application Notes: continued
from the die junction to ambient air. The maximum junc-
tion temperature can be determined by:
T
J(max)
= T
A(max)
+ P
D(max)
R
QJA
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:
P
D(max)
= (V
IN(max)
-V
OUT(min)
)I
OUT(max)
+ V
IN(max)
I
IN(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 which is measured in degrees per watt.
Like series electrical resistances, these thermal resistances
are summed to determine the total thermal resistance
between the die junction and the surrounding air, R
QJA
.
This total thermal resistance is comprised of three compo-
nents. These resistive terms are measured from junction to
case (R
QJC
), case to heat sink (R
QCS
), and heat sink to ambi-
ent air (R
QSA
). The equation is:
R
QJA
= R
QJC
+ R
QCS
+ R
QSA
R
QJC
is rated @ 1.4C/W for the CS5210-1. For a high cur-
rent regulator such as the CS5210-1 the majority of heat is
generated in the power transistor section. The value for
R
QSA
depends on the heat sink type, while the R
QCS
depends on factors such as package type, heat sink inter-
face (is an insulator and thermal grease used?), and the
contact area between the heat sink and the package. Once
these calculations are complete, the maximum permissible
value of R
QJA
can be calculated and the proper heat sink
selected. For further discussion on heat sink selection, see
our Cherry application note Thermal Management for
Linear Regulators.
CS5210-1
Application Notes: continued
7
CS5210-1
8
Rev. 6/12/97
1999 Cherry Semiconductor Corporation
Thermal Data
3L
TO-220
R
QJC
typ
1.4
C/W
R
QJA
typ
50
C/W
Package Specification
PACKAGE DIMENSIONS IN mm (INCHES)
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 THERMAL DATA
Ordering Information
Part Number
Description
CS5210-1GT3
3L TO-220 Straight
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)
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