ETC CS5210-1/D

CS5210-1
10 A LDO 3-Pin Adjustable
Linear Regulator
The CS5210–1 linear regulator provides 10 A at adjustable voltages
from 1.25 V to 4.5 V. This adjustable device requires two external
resistors 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 regulator 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
1.05 V at 10 A.
The regulator is protected against overload conditions with
overcurrent and thermal shutdown protection circuitry.
The regulator is available in a TO–220 package.
Features
• 1.25 V to 4.5 V VOUT at 10 A
• Dropout Voltage < 1.05 V @ 10 A
• 2.0% Trimmed Reference
• Fast Transient Response
• Thermal Shutdown
• Current Limit
• Short Circuit Protection
2
3
Tab = VOUT
Pin 1. Adjust
2. VOUT
3. VIN
3.3 V @ 10 A
1
CS5210–1
A
WL, L
YY, Y
WW, W
124
100 µF
Load
0.1 µF
1
CS5210–1
AWLYWW
VOUT
Adj
TO–220
THREE LEAD
T SUFFIX
CASE 221A
PIN CONNECTIONS AND
MARKING DIAGRAMS
5.0 V
VIN
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200
300 µF
= Assembly Location
= Wafer Lot
= Year
= Work Week
ORDERING INFORMATION
Device
CS5210–1GT3
Package
Shipping
TO–220*
50 Units/Rail
*TO–220 is 3–pin, straight leaded.
Figure 1. Applications Diagram
 Semiconductor Components Industries, LLC, 2001
February, 2001 – Rev. 4
1
Publication Order Number:
CS5210–1/D
CS5210–1
ABSOLUTE MAXIMUM RATINGS*
Parameter
Value
Unit
6.0
V
Operating Ambient Temperature Range
0 ≤ TA ≤ 70
°C
Operating Junction Temperature Range
0 ≤ TJ ≤ 150
°C
Storage Temperature Range
–65 to +150
°C
260 Peak
°C
2.0
kV
Input Voltage
Lead Temperature Soldering:
Wave Solder (through hole styles only) Note 1.
ESD Damage Threshold
1. 10 second maximum.
*The maximum package power dissipation must be observed.
ELECTRICAL CHARACTERISTICS ( 0°C ≤ TA ≤ 70°C, 0°C ≤ TJ ≤ 150°C, VAdj = 0 V, unless otherwise specified.)
Characteristic
Test Conditions
Min
Typ
Max
Unit
1.227
(–2.0%)
1.253
1.278
(+2.0%)
V
Adjustable Output Voltage
Reference Voltage
VIN = 2.75 V to 5.5 V,
IOUT = 10 mA to 10 A
Line Regulation
VIN = 2.75 V to 5.5 V, IOUT = 10 mA
–
0.02
0.20
%
Load Regulation
VIN = 2.75 V, IOUT = 10 mA to 10 A
–
0.04
0.50
%
Minimum Load Current (Note 2.)
VIN = 5.0 V, ∆VOUT = +2.0%
–
5.0
10
mA
Adjust Pin Current
VIN = 2.75 V, IOUT = 10 mA
–
70
120
µA
Current Limit
VIN = 2.75 V, ∆VOUT = –2.0%
10.1
12
–
A
Short Circuit Current
VIN = 2.75 V, VOUT = 0 V
8.0
10
–
A
Ripple Rejection (Note 3.)
VIN = 3.25 V Avg, VRIPPLE = 1.0 VP–P @ 120 Hz,
IOUT = 4.0 A, CAdj = 0.1 µF; COUT = 22 µF
60
80
–
dB
Thermal Regulation (Note 3.)
30 ms Pulse, TA = 25°C
–
0.002
–
%/W
Dropout Voltage (Minimum VIN–VOUT)
(Note 4.)
IOUT = 100 mA
IOUT = 1.0 A
IOUT = 2.75 A
IOUT = 4.0 A
IOUT = 10 A
–
–
–
–
–
0.92
0.93
0.94
0.95
1.03
1.15
1.15
1.15
1.15
1.40
V
V
V
V
V
RMS Output Noise
Freq = 10 Hz to 10 kHz, TA = 25°C
–
0.003
–
%VOUT
Temperature Stability
–
–
0.5
–
%
Thermal Shutdown (Note 5.)
–
150
180
210
°C
Thermal Shutdown Hysteresis (Note 5.)
–
–
25
–
°C
2. 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.
3. This parameter is guaranteed by design and is not 100% production tested.
4. Dropout voltage is defined as the minimum input/output voltage differential required to maintain 2.0% regulation.
5. This parameter is guaranteed by design, but not parametrically tested in production. However, a 100% thermal shutdown functional test is
performed on each part.
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2
CS5210–1
PACKAGE PIN DESCRIPTION
Package Pin Number
TO–220
Pin Symbol
Function
1
Adjust
This pin is connected to the low side of the internally trimmed 2.0% bandgap reference
voltage and carries a bias current of about 70 µA. A resistor divider from Adj to VOUT 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
VOUT
This pin is connected to the emitter of the power pass transistor and provides a regulated
voltage capable of sourcing 10 A of current.
3
VIN
This is the supply voltage for the regulator. For the device to regulate, this voltage should be
between 1.2 V and 1.40 V (depending on the output current) greater than the output voltage.
VIN
BIAS
and
TSD
–
EA
+
VREF
+
IA
–
VOUT
Adj
Figure 2. Block Diagram
TYPICAL PERFORMANCE CHARACTERISTICS
90
IO = 10 mA
Adjust Pin Current (µA)
Adjust Pin Current (µA)
85
80
75
70
65
60
0
10 20 30
73.00
72.80
72.60
72.40
72.20
72.00
71.80
71.60
71.40
71.20
71.00
70.80
70.60
70.40
70.20
70.00
40 50 60 70 80 90 100 110 120 130
0
1
2
3
4
5
6
7
8
TCASE (°C)
IOUT (A)
Figure 3. Adjust Pin Current Voltage vs.
Temperature
Figure 4. Adjust Pin vs. IOUT
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3
9
10
CS5210–1
0.350
0.100
IO = 10 mA
VIN = 2.75 V
Output Voltage Deviation (%)
Output Voltage Deviation (%)
0.075
0.050
0.025
0.000
–0.025
–0.050
–0.075
–0.100
–0.125
–0.150
0.300
TCASE = 125°C
0.250
0.200
TCASE = 25°C
0.150
0.100
TCASE = 0°C
0.050
0.000
0
10 20 30 40 50 60 70 80 90 100 110 120 130
0
1
2
3
4
5
6
7
8
9
TJ (°C)
Output Current (A)
Figure 5. Reference Voltage vs.
Temperature
Figure 6. Load Regulation vs. Output
Current
10
1.250
90
1.000
70
VDROPOUT (mV)
Ripple Rejection (dB)
80
60
50
VIN – VOUT = 2.0 V
40
IOUT = 4.0 A
VRIPPLE = 1.0 VPP
COUT = 22 µF
CAdj = 0.1 µF
30
20
10
101
102
103
0.500
0.250
104
105
0.000
106
0
1
2
3
4
5
6
7
8
Frequency (Hz)
Output Current (A)
Figure 7. Ripple Rejection vs. Frequency
Figure 8. VDROPOUT vs. IOUT
1.00
18
0.98
Minimum Load Current (mA)
20
16
Output Current (A)
0.750
14
12
10
8
6
4
2
9
10
0.96
0.94
TCASE = 25°C
TCASE = 125°C
0.92
0.90
0.88
0.86
0.84
TCASE = 0°C
0.82
0
0.80
0.0
0.5 1.0 1.5 2.0
2.5 3.0 3.5 4.0 4.5
5.0 5.5
1
2
3
4
VIN – VOUT (V)
VIN – VOUT (V)
Figure 9. Short Circuit vs. VIN – VOUT
Figure 10. Minimum Load Current vs.
VIN – VOUT
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5
CS5210–1
APPLICATION NOTES
THEORY OF OPERATION
The CS5210–1 linear regulator has an absolute maximum
specification of 6.0 V for the voltage difference between VIN
and VOUT. However, the IC may be used to regulate voltages
in excess of 6.0 V. 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
milliseconds, while the regulator responds in less than one
microsecond. In this case, the linear regulator begins
charging the output capacitor as soon as the VIN to VOUT
differential is large enough that the pass transistor conducts
current. VOUT is essentially at ground, and VIN is on the
order of several hundred millivolts, so the pass transistor is
in dropout. As VIN increases, the pass transistor will remain
in dropout, and current is passed to the load until VOUT is in
regulation. Further increase in VIN 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 VIN to VOUT differential of
6.0 V is not exceeded.
However, the 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 VIN to VOUT differential
to less than 6.0 V if failsafe operation is required. One
possible clamp circuit is illustrated in Figure 12; however, the
design of clamp circuitry 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 conditions
indefinitely while protecting the IC.
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
included in the Stability Considerations section.
ADJUSTABLE OPERATION
Design Guidelines
This LDO adjustable regulator has an output voltage
range of 1.25 V to 4.5 V. An external resistor divider sets the
output voltage as shown in Figure 11. The regulator’s
voltage sensing error amplifier maintains a fixed 1.25 V
reference between the output pin and the adjust pin.
A resistor divider network R1 and R2 causes a fixed 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 µA) 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:
R R2
VOUT VREF 1
R2 IAdj
R1
The term IAdj × R2 represents the error added by the adjust
pin current.
R1 is chosen so that the minimum load current is at least
10 mA. R1 and R2 should be of the same composition for best
tracking over temperature. The divider resistors should be
placed as close to the IC as possible and connected to the
output with a seperate metal trace.
VIN
VOUT
CS5210–1
Adj
R1
EXTERNAL SUPPLY
R2
Figure 11.
While not required, a bypass capacitor connected between
the adjust pin and ground will improve transient response
and ripple rejection. A 0.1 µF tantalum capacitor is
recommended for “first cut” design. Value and type may be
varied to optimize performance vs price.
VIN
VOUT
VAdj
Figure 12.
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CS5210–1
STABILITY CONSIDERATIONS
If the calculated current is greater than or equal to the
typical short circuit current value provided in the
specifications, serious thought should be given to including
a protection diode.
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
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 300 µF tantalum capacitor will work for most
applications, but with high current regulators such as the
CS5210–1 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:
VIN
CS5210–1
Adj
Figure 13.
Current Limit
The internal current limit circuit limits the output current
under excessive load conditions and protects the regulator.
V I ESR
Short Circuit Protection
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.
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 150°C
and to shut down the regulator output. This circuitry
includes a thermal hysteresis circuit with 25°C of typical
hysteresis, thereby allowing the regulator to recover from a
thermal fault automatically.
Protection Diodes
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 VIN drops. In the
CS5210–1 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 13 is recommended.
A rule of thumb useful in determining if a protection diode
is required is to solve for current
I
VOUT
Calculating Power Dissipation and Heat Sink
Requirements
High power regulators such as the CS5210–1 usually
operate at high junction temperatures. Therefore, it is
important to calculate the power dissipation and junction
temperatures 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, thermal
compound is necessary to ensure proper heat flow. For
added safety, this high current LDO includes an internal
thermal shutdown circuit
The thermal characteristics of an IC depend on the
following four factors. Junction temperature, ambient
temperature, die power dissipation, and the thermal
resistance from the die junction to ambient air. The
maximum junction temperature can be determined by:
CV
T
where:
I is the current flow out of the load capacitance when VIN
is shorted,
C is the value of the load capacitance,
V is the output voltage, and
T is the time duaration required for VIN to transition from
high to being shorted.
TJ(max) TA(max) PD(max) RJA
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CS5210–1
RJA RJC RCS RSA
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
maximum power dissipation for a regulator is:
RΘJC is rated @ 1.4°C/W for the CS5210–1. For a high
current regulator such as the CS5210–1 the majority of heat
is generated in the power transistor section. The value for
RΘSA depends on the heat sink type, while the RΘCS depends
on factors such as package type, heat sink interface (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 RΘJA can be calculated and the proper heat sink selected.
For further discussion on heat sink selection, see application
note “Thermal Management for Linear Regulators,”
document number SR006AN/D, available through the
Literature Distribution Center or via our website at
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PD(max) (VIN(max) VOUT(min))IOUT(max) VIN(max) IIN(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 the total thermal
resistance between the die junction and the surrounding air,
RΘJC. This total thermal resistance is comprised of three
components. These resistive terms are measured from
junction to case (RΘJC), case to heat sink (RΘCS), and heat
sink to ambient air (RΘSA). The equation is:
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CS5210–1
PACKAGE DIMENSIONS
TO–220
THREE LEAD
T SUFFIX
CASE 221A–09
ISSUE AA
SEATING
PLANE
–T–
B
C
F
T
S
4
DIM
A
B
C
D
F
G
H
J
K
L
N
Q
R
S
T
U
V
Z
A
Q
1 2 3
U
H
K
Z
L
R
V
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION Z DEFINES A ZONE WHERE ALL
BODY AND LEAD IRREGULARITIES ARE
ALLOWED.
J
G
D
N
INCHES
MIN
MAX
0.570
0.620
0.380
0.405
0.160
0.190
0.025
0.035
0.142
0.147
0.095
0.105
0.110
0.155
0.018
0.025
0.500
0.562
0.045
0.060
0.190
0.210
0.100
0.120
0.080
0.110
0.045
0.055
0.235
0.255
0.000
0.050
0.045
----0.080
MILLIMETERS
MIN
MAX
14.48
15.75
9.66
10.28
4.07
4.82
0.64
0.88
3.61
3.73
2.42
2.66
2.80
3.93
0.46
0.64
12.70
14.27
1.15
1.52
4.83
5.33
2.54
3.04
2.04
2.79
1.15
1.39
5.97
6.47
0.00
1.27
1.15
----2.04
PACKAGE THERMAL DATA
Parameter
TO–220
THREE LEAD
Unit
RΘJC
Typical
1.4
°C/W
RΘJA
Typical
50
°C/W
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without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular
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CS5210–1/D