ETC CS5253B

CS5253B-1
3.0 A LDO 5-Pin Adjustable
Linear Regulator with
Remote Sense Applications
This new very low dropout linear regulator reduces total power
dissipation in the application. To achieve very low dropout, the
internal pass transistor is powered separately from the control
circuitry. Furthermore, with the control and power inputs tied together,
this device can be used in single supply configuration and still offer a
better dropout voltage than conventional PNP–NPN based LDO
regulators. In this mode the dropout is determined by the minimum
control voltage.
The CS5253B–1 is offered in a five–terminal D2PAK package,
which allows for the implementation of a remote–sense pin permitting
very accurate regulation of output voltage directly at the load, where it
counts, rather than at the regulator. This remote sensing feature
virtually eliminates output voltage variations due to load changes and
resistive voltage drops. Typical load regulation measured at the sense
pin is less than 1.0 mV for an output voltage of 2.5 V with a load step
of 10 mA to 3.0 A.
The CS5253B–1 has a very fast transient loop response which can
be adjusted using a small capacitor on the Adjust pin.
Internal protection circuitry provides for “bust–proof” operation,
similar to three–terminal regulators. This circuitry, which includes
overcurrent, short circuit, and overtemperature protection will self
protect the regulator under all fault conditions.
The CS5253B–1 is ideal for generating a 2.5 V supply to power
graphics controllers used on VGA cards. Its remote sense and low
value capacitance requirements make this a low cost, high
performance solution. The CS5253B–1 is optimized from the
CS5253–1 to allow a lower value of output capacitor to be used at the
expense of a slower transient response.
Features
VOUT Range is 1.25 V to 5.0 V @ 3.0 A
VPOWER Dropout < 0.40 V @ 3.0 A
VCONTROL Dropout < 1.05 V @ 3.0 A
1.0% Trimmed Reference
Fast Transient Response
Remote Voltage Sensing
Thermal Shutdown
Current Limit
Short Circuit Protection
Drop–In Replacement for EZ1582
Backwards Compatible with 3–Pin Regulators
Very Low Dropout Reduces Total Power Consumption
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 Semiconductor Components Industries, LLC, 2001
April, 2001 – Rev. 2
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Tab = VOUT
Pin 1. VSENSE
2. Adjust
3. VOUT
4. VCONTROL
5. VPOWER
1
5
D2PAK
5–PIN
DP SUFFIX
CASE 936F
MARKING DIAGRAM
CS
5253B–1
AWLYWW
1
A
WL, L
YY, Y
WW, W
= Assembly Location
= Wafer Lot
= Year
= Work Week
ORDERING INFORMATION
Device
Package
Shipping
CS5253B–1GDP5
D2PAK*
50 Units/Rail
CS5253B–1GDPR5
D2PAK*
750 Tape & Reel
*5–Pin.
1
Publication Order Number:
CS5253B–1/D
CS5253B–1
5.0 V
RDIS
VOUT
VCONTROL
2.5 V @ 3.0 A
CS5253B–1
VPOWER
VSENSE
3.3 V
124
Adjust
10 µF
10 V
100 µF
5.0 V
33 µF
5.0 V
CLOAD
(Optional)
124
GND
GND
RDIS
Figure 1. Application Diagram
MAXIMUM RATINGS*
Rating
Value
Unit
VPOWER Input Voltage
6.0
V
VCONTROL Input Voltage
13
V
0 to 150
°C
–65 to +150
°C
2.0
kV
230 peak
°C
Operating Junction Temperature Range, TJ
Storage Temperature Range
ESD Damage Threshold
Lead Temperature Soldering:
Reflow: (SMD styles only) (Note 1)
1. 60 second maximum above 183°C.
*The maximum package power dissipation must be observed.
ELECTRICAL CHARACTERISTICS (0°C ≤ TA ≤ 70°C; 0°C ≤ TJ ≤ 150°C; VSENSE = VOUT and VADJ = 0 V; unless
otherwise specified.)
Characteristic
Test Conditions
Min
Typ
Max
Unit
Reference Voltage
VCONTROL = 2.75 V to 12 V, VPOWER = 2.05 V to 5.5 V,
IOUT = 10 mA to 3.0 A
1.237
(–1.0%)
1.250
1.263
(+1.0%)
V
Line Regulation
VCONTROL = 2.5 V to 12 V, VPOWER = 1.75 V to 5.5 V,
IOUT = 10 mA
–
0.02
0.2
%
Load Regulation
VCONTROL = 2.75 V, VPOWER = 2.05 V,
IOUT = 10 mA to 3.0 A, with Remote Sense
–
0.04
0.3
%
Minimum Load Current (Note 2)
VCONTROL = 5.0 V, VPOWER = 3.3 V, ∆VOUT = +1.0%
–
5.0
10
mA
Control Pin Current (Note 3)
VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 100 mA
VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 3.0 A
–
–
6.0
35
10
120
mA
mA
Adjust Pin Current
VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 10 mA
–
60
120
µA
Current Limit
VCONTROL = 2.75 V, VPOWER = 2.05 V, ∆VOUT = –4.0%
3.1
4.0
–
A
Short Circuit Current
VCONTROL = 2.75 V, VPOWER = 2.05 V, VOUT = 0 V
2.0
3.5
–
A
Ripple Rejection (Note 4)
VCONTROL = VPOWER = 3.25 V, VRIPPLE = 1.0 VP–P @
120 Hz, IOUT = 3.0 A, CADJ = 0.1 µF
60
80
–
dB
CS5253B–1
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. The VCONTROL pin current is the drive current required for the output transistor. This current will track output current with roughly a 1:100
ratio. The minimum value is equal to the quiescent current of the device.
4. This parameter is guaranteed by design and is not 100% production tested.
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CS5253B–1
ELECTRICAL CHARACTERISTICS (continued) (0°C ≤ TA ≤ 70°C; 0°C ≤ TJ ≤ 150°C; VSENSE = VOUT and VADJ = 0 V; unless
otherwise specified.)
Characteristic
Test Conditions
Min
Typ
Max
Unit
CS5253B–1 (continued)
Thermal Regulation
30 ms Pulse, TA = 25°C
–
0.002
–
%/W
VCONTROL Dropout Voltage
(Minimum VCONTROL – VOUT)
(Note 5)
VPOWER = 2.05 V, IOUT = 100 mA
VPOWER = 2.05 V, IOUT = 1.0 A
VPOWER = 2.05 V, IOUT = 3.0 A
–
–
–
0.90
1.00
1.05
1.15
1.15
1.30
V
V
V
VPOWER Dropout Voltage
(Minimum VPOWER – VOUT)
(Note 5)
VCONTROL = 2.75 V, IOUT = 100 mA
VCONTROL = 2.75 V, IOUT = 1.0 A
VCONTROL = 2.75 V, IOUT = 3.0 A
–
–
–
0.05
0.15
0.40
0.15
0.25
0.60
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 6)
–
150
180
210
°C
Thermal Shutdown Hysteresis
–
–
25
–
°C
VCONTROL Supply Only Output
Current
VCONTROL = 13 V, VPOWER Not Connected,
VADJ = VOUT = VSENSE = 0 V
–
–
50
mA
VPOWER Supply Only Output
Current
VPOWER = 6.0 V, VCONTROL Not Connected,
VADJ = VOUT = VSENSE = 0 V
–
0.1
1.0
mA
5. Dropout is defined as either the minimum control voltage (VCONTROL) or minimum power voltage (VPOWER) to output voltage differential
required to maintain 1.0% regulation at a particular load current.
6. This parameter is guaranteed by design, but not parametrically tested in production. However, a 100% thermal shutdown functional test
is performed on each part.
PACKAGE PIN DESCRIPTION
PACKAGE PIN #
D2PAK
PIN SYMBOL
1
VSENSE
This Kelvin sense pin allows for remote sensing of the output voltage at the
load for improved regulation. It is internally connected to the positive input of
the voltage sensing error amplifier.
2
Adjust
This pin is connected to the low side of the internally trimmed 1.0% bandgap
reference voltage and carries a bias current of about 50 µA. A resistor divider
from Adjust to VOUT and from Adjust to ground sets the output voltage. Also,
transient response can be improved by adding a small bypass capacitor from
this pin to ground.
3
VOUT
This pin is connected to the emitter of the power pass transistor and provides a
regulated voltage capable of sourcing 3.0 A of current.
4
VCONTROL
5
VPOWER
FUNCTION
This is the supply voltage for the regulator control circuitry. For the device to
regulate, this voltage should be between 0.9 V and 1.3 V (depending on the
output current) greater than the output voltage. The control pin current will be
about 1.0% of the output current.
This is the power input voltage. This pin is physically connected to the collector
of the power pass transistor. For the device to regulate, this voltage should be
between 0.1 V and 0.6 V greater than the output voltage depending on the output current. The output load current of 3.0 A is supplied through this pin.
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CS5253B–1
VPOWER
VCONTROL
BIAS
and
TSD
EA
–
+
VREF
IA
+
–
VOUT
VSENSE
Adjust
Figure 2. Block Diagram
0.12
1.252
0.10
Load Regulation (%)
1.253
1.251
1.250
1.249
1.248
1.247
TJ = 120°C
0.08
0.06
TJ = 20°C
0.04
TJ = 0°C
0.02
0
20
40
60
80
100
0
120
0
0.5
Junction Temperature (°C)
15 A/µs
1.5
2.0
2.5
3.0
Figure 4. Load Regulation vs Output Current
5.0
VCONTROL = 5.0 V
VPOWER = 3.3 V
VOUT = 2.5 V
CCONTROL = 10 µF
CADJ = 0.1 µF
1.0
Output Current (A)
Figure 3. Reference Voltage vs Junction Temperature
VOUT
CS5253–1
COUT = 330 µF
VOUT
CS5253B–1
COUT = 33 µF
Measured at ∆VOUT = –1.0%
4.5
4.0
Output Current (A)
Reference Voltage (V)
TYPICAL PERFORMANCE CHARACTERISTICS
3.5
3.0
2.5
2.0
1.5
1.0
80 A/µs
ILOAD
10 mA to 3.0 A
0.5
0
0
1
2
3
4
5
VPOWER – VOUT (V)
Figure 6. Output Current vs VPOWER – VOUT
Figure 5. Transient Response Comparison between
CS5253–1 and CS5253B–1
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6
CS5253B–1
85
Minimum Load Current (µA)
1200
IADJ (µA)
80
75
70
65
VPOWER = 3.3 V
∆VOUT = +1.0%
1150
1100
1050
1000
950
900
850
60
0
20
40
60
80
100
120
800
1.0
140
2.0
3.0
Junction Temperature (°C)
VCONTROL = 5.0 V
VPOWER = 3.3 V
8.0
9.0
10
11
Ripple Rejection (dB)
80
3.7
3.6
3.5
3.4
70
60
50
VIN – VOUT = 2.0 V
IOUT = 3.0 A
VRIPPLE = 1.0 VP–P
COUT = 22 µF
CADJ = 0.1 µF
40
30
20
0
20
40
60
80
100
120
10
101
140
102
103
104
105
106
Frequency (Hz)
Junction Temperature (°C)
Figure 9. Short Circuit Output Current vs Junction
Temperature
Figure 10. Ripple Rejection vs Frequency
1100
12
VCONTROL Dropout Voltage (mV)
VCONTROL = 13 V
VOUT = 0 V
VPOWER Not Connected
10
8
IOUT (mA)
7.0
90
3.8
6
4
2
0
6.0
Figure 8. Minimum Load Current vs VCONTROL – VOUT
3.9
Short Circuit Output Current Limit (A)
5.0
VCONTROL – VOUT (V)
Figure 7. Adjust Pin Current vs Junction Temperature
3.3
4.0
0
20
40
60
80
100
120
140
VPOWER = 2.05 V
TJ = 0°C
1000
TJ = 20°C
900
TJ = 120°C
800
0
0.5
1.0
1.5
2.0
2.5
Output Current (A)
Junction Temperature (°C)
Figure 11. VCONTROL Only Output Current vs Junction
Temperature
Figure 12. VCONTROL Dropout Voltage vs Output
Current
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3.0
CS5253B–1
916.4
400
TJ = 120°C
350
300
TJ = 0°C
250
TJ = 20°C
200
150
50
0
VCONTROL = 5.0 V
∆VOUT = +1.0%
916.3
450
Minimum Load Current (µA)
VPOWER Dropout Voltage (V)
500
916.2
916.1
916.0
915.9
915.8
915.7
915.6
915.5
0
0.5
1.0
1.5
2.0
2.5
3.0
915.4
0.5
1.5
2.5
VPOWER – VOUT (V)
Output Current (A)
Figure 13. VPOWER Dropout Voltage vs Output
Current
4.5
Figure 14. Minimum Load Current vs VPOWER – VOUT
30
40
VPOWER = 6.0 V
VOUT = 0 V
VCONTROL Not Connected
ICONTROL (mA)
25
20
IOUT (µA)
3.5
15
10
35
VCONTROL = 2.75 V
VPOWER = 2.05 V
30
IOUT = 3.0 A
25
20
15
IOUT = 1.0 A
10
5
0
IOUT = 100 mA
5
0
20
40
80
60
100
120
0
140
0
20
Junction Temperature (°C)
60
80
100
120
140
Junction Temperature (°C)
Figure 15. VPOWER Only Output Current vs Junction
Temperature
Figure 16. VCONTROL Supply Current vs Junction
Temperature
5.0
6
VPOWER = 3.3 V
VCONTROL = 5.0 V
VOUT set for 2.5 V
TA = 25°C
VPOWER = 3.3 V
VCONTROL = 5.0 V
ILOAD = 0 to 3.0 A
5
VOUT = 2.5 V
VOUT Shorted to VSENSE
TJ = 0°C to 150°C
4
4.5
ESR (Ω)
Current Limit (A)
40
Unstable
3
2
4.0
Stable Region
1
3.5
0
0.5
1.0
1.5
2.0
2.5
3.0
0
0
10
20
30
40
50
60
70
Capacitance (µF)
VOUT (V)
Figure 18. Stability vs ESR
Figure 17. Current Limit vs VOUT
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80
90
100
CS5253B–1
APPLICATIONS NOTES
THEORY OF OPERATION
Output Voltage Sensing
The CS5253B–1 linear regulator provides adjustable
voltages from 1.25 V to 5.0 V at currents up to 3.0 A. The
regulator is protected against short circuits, and includes a
thermal shutdown circuit with hysteresis. The output, which
is current limited, consists of a PNP–NPN transistor pair and
requires an output capacitor for stability. A detailed
procedure for selecting this capacitor is included in the
Stability Considerations section.
The CS5253B–1 five terminal linear regulator includes a
dedicated VSENSE function. This allows for true Kelvin
sensing of the output voltage. This feature can virtually
eliminate errors in the output voltage due to load regulation.
Regulation will be optimized at the point where the sense pin
is tied to the output.
VPOWER Function
Remote Sense
DESIGN GUIDELINES
Remote sense operation can be easily obtained with the
CS5253B–1 but some care must be paid to the layout and
positioning of the filter capacitors around the part. The
ground side of the input capacitors on the +5.0 V and +3.3 V
lines and the local VOUT–to–ground local output capacitor
on the IC output must be tied close to the ground connected
resistor voltage divider feedback network. The top resistor
of the divider must be connected directly to the VSENSE pin
of the regulator. This will establish the stability of the part.
This capacitor–divider resistor connection may then be
connected to ground remotely at the load, giving the ground
portion remote sense operation.
The VSENSE line can then be tied remotely at the load
connection, giving the feedback remote sense operation.
The remote sense lines should be Kelvin connected so as to
eliminate the effect of load current voltage drop. An optional
bypass capacitor may be used at the load to reduce the effect
of load variations and spikes.
The CS5253B–1 utilizes a two supply approach to
maximize efficiency. The collector of the power device is
brought out to the VPOWER pin to minimize internal power
dissipation under high current loads. VCONTROL provides
for the control circuitry and the drive for the output NPN
transistor. VCONTROL should be at least 1.0 V greater than
the output voltage. Special care has been taken to ensure that
there are no supply sequencing problems. The output
voltage will not turn on until both supplies are operating. If
the control voltage comes up first, the output current will be
limited to about three milliamperes until the power input
voltage comes up. If the power input voltage comes up first,
the output will not turn on at all until the control voltage
comes up. The output can never come up unregulated.
The CS5253B–1 can also be used as a single supply device
with the control and power inputs tied together. In this mode,
the dropout will be determined by the minimum control
voltage.
RDIS
+5.0 V
VCONTROL
+3.3 V
VPOWER
VSENSE
CS5253B–1
+
10 µF
+
+Load
VOUT
124
+
ADJ
100 µF
33 µF
Remote
Connections
+
Optional
124
Local
Connections
–Load
GND
RDIS
Figure 19. Remote Sense
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CS5253B–1
Adjustable Operation
remain in dropout, and current is passed to the load until
VOUT is in regulation. Further increase in the supply voltage
brings the pass transistor out of dropout. In this manner, any
output voltage less than 13 V may be regulated, provided the
VPOWER to VOUT differential is less than 6.0 V. In the case
where VCONTROL and VPOWER are shorted, there is no
theoretical limit to the regulated voltage as long as the
VPOWER to VOUT differential of 6.0 V is not exceeded.
There is a possibility of damaging the IC when VPOWER
– VOUT is greater than 6.0 V if a short circuit occurs. Short
circuit conditions will result in the immediate operation of
the pass transistor outside of its safe operating area.
Overvoltage 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 the VPOWER to VOUT differential to less than 6.0 V
if fail safe operation is required. One possible clamp circuit
is illustrated in Figure 21; 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 condition
indefinitely while protecting the IC.
This LDO adjustable regulator has an output voltage
range of 1.25 V to 5.0 V. An external resistor divider sets the
output voltage as shown in Figure 20. The regulator’s
voltage sensing error amplifier maintains a fixed 1.25 V
reference between the output pin and the adjust pin.
5.0 V
VCONTROL
VOUT
2.5 V
@ 3.0 A
CS5253B–1
3.3 V
VPOWER
VSENSE
Adjust
R1
R2
Figure 20. Typical Application Schematic. The
Resistor Divider Sets VOUT, With the Internal
1.260 V Reference Dropped Across R1.
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:
VOUT 1.25 V External Supply
External
Supply
VCONTROL
VSENSE
CS5253B–1
VPOWER
VOUT
R1 R2
R2 IADJ
R1
VADJ
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.
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.
Figure 21. This Circuit Is an Example of How the
CS5253B–1 Can Be Short–Circuit Protected When
Operating With VOUT > 6.0 V
Stability Considerations
Other Adjustable Operation Considerations
The output compensation capacitor helps determine three
main characteristics of a linear regulator: loop stability,
start–up delay, and load transient response. Different
capacitor types vary widely in tolerance, ESR (equivalent
series resistance), ESL (equivalent series inductance), and
variation over temperature. Tantalum and aluminum
electrolytic capacitors work best, with electrolytic
capacitors being less expensive in general, but varying more
in capacitor value and ESR over temperature.
The CS5253B–1 requires an output capacitor to guarantee
loop stability. The Stability vs ESR graph in the typical
performance section shows the minimum ESR needed to
The CS5253B–1 linear regulator has an absolute
maximum specification of 6.0 V for the voltage difference
between VPOWER and VOUT. However, the IC may be used
to regulate voltages in excess of 6.0 V. The two main
considerations in such a design are the sequencing of power
supplies and short circuit capability.
Power supply sequencing should be such that the
VCONTROL supply is brought up coincidentally with or
before the VPOWER supply. This allows the IC to begin
charging the output capacitor as soon as the VPOWER to
VOUT differential is large enough that the pass transistor
conducts. As VPOWER increases, the pass transistor will
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CS5253B–1
guarantee stability, but under ideal conditions. These
include: having VOUT connected to VSENSE directly at the
IC pins; the compensation capacitor located right at the pins
with a minimum lead length; the adjust feedback resistor
divider ground, (bottom of R2 in Figure 20), connected right
at the capacitor ground; and with power supply decoupling
capacitors located close to the IC pins. The actual
performance will vary greatly with board layout for each
application. In particular, the use of the remote sensing
feature will require a larger capacitor with less ESR. For
most applications, a minimum of 33 µF tantalum or 150 µF
aluminum electrolytic, with an ESR less than 1.0 Ω over
temperature, is recommended. Larger capacitors and lower
ESR will improve stability.
The load transient response, during the time it takes the
regulator to respond, is also determined by the output
capacitor. For large changes in load current, the ESR of the
output capacitor causes an immediate drop in output voltage
given by:
VCONTROL
VOUT
CS5253B–1
VPOWER
VSENSE
Adjust
Figure 22. Diode Protection Circuit
A rule of thumb useful in determining if a protection diode
is required is to solve for current:
ICV
T
V I ESR
where:
I is the current flow out of the load capacitance when
VCONTROL is shorted,
C is the value of load capacitance
V is the output voltage, and
T is the time duration required for VCONTROL to transition
from high to being shorted.
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 the use of
a protection diode.
There is then an additional drop in output voltage given
by:
V I TC
where T is the time for the regulation loop to begin to
respond. The very fast transient response time of the
CS5253B–1 allows the ESR effect to dominate. 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 transient
response.
Current Limit
The internal current limit circuit limits the output current
under excessive load conditions.
Protection Diodes
Short Circuit Protection
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 VCONTROL drops. In
the CS5253B–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 22 is recommended.
The device includes short circuit protection circuitry that
clamps the output current at approximately 500 mA less than
its current limit value. This provides for a current foldback
function, which reduces power dissipation under a direct
shorted load.
Thermal Shutdown
The thermal shutdown circuitry is guaranteed by design to
activate above a die junction temperature of approximately
150°C and to shut down the regulator output. This circuitry
has 25°C of typical hysteresis, thereby allowing the
regulator to recover from a thermal fault automatically.
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CS5253B–1
Calculating Power Dissipation and
Heat Sink Requirements
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, RΘJA. 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:
High power regulators such as the CS5253B–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
CS5253B–1, electrical isolation may be required for some
applications. Also, as with all high power packages, thermal
compound in 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:
RJA RJC RCS RSA
The value for RQJC is 2.5°C/watt for the CS5253B–1 in
the D2PAK package. For a high current regulator such as the
CS5253B–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 our application note “Thermal
Management for Linear Regulators,” document number
SR006AN/D, available through the Literature Distribution
Center or via our website at http://www.onsemi.com.
TJ(max) TA(max) PD(max) RJA
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:
PD(max) (VIN(max) VOUT(min))IOUT(max)
VIN(max) IIN(max)
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10
CS5253B–1
PACKAGE DIMENSIONS
D2PAK
5–PIN
DP SUFFIX
CASE 936F–01
ISSUE O
–T– SEATING
PLANE
B
M
NOTES:
1. DIMENSIONS AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. TAB CONTOUR OPTIONAL WITHIN DIMENSIONS
B AND M.
4. DIMENSIONS A AND B DO NOT INCLUDE MOLD
FLASH OR GATE PROTRUSIONS. MOLD FLASH
AND GATE PROTRUSIONS NOT TO EXCEED
0.025 (0.635) MAX.
C
E
DIM
A
B
C
D
E
F
G
H
J
K
M
N
A
1 2 3 4 5
K
F
G
D
H
5 PL
0.13 (0.005)
M
T B
J
M
INCHES
MIN
MAX
0.326
0.336
0.396
0.406
0.170
0.180
0.026
0.035
0.045
0.055
0.090
0.110
0.067 BSC
0.098
0.108
0.018
0.025
0.204
0.214
0.055
0.066
0.000
0.004
N
PACKAGE THERMAL DATA
Parameter
D2PAK, 5–Pin
Unit
RΘJC
Typical
2.5
°C/W
RΘJA
Typical
10–50*
°C/W
*Depending on thermal properties of substrate. RΘJA = RΘJC + RΘCA.
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11
MILLIMETERS
MIN
MAX
8.28
8.53
10.05
10.31
4.31
4.57
0.66
0.91
1.14
1.40
2.29
2.79
1.70 BSC
2.49
2.74
0.46
0.64
5.18
5.44
1.40
1.68
0.00
0.10
CS5253B–1
ON Semiconductor and
are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes
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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12
CS5253B–1/D