Page 1
1
Features
■ Output Current to 7A
■ Output Voltage Trimmed
to ±2%
■ Dropout Voltage
1.45V @ 7A
■ Fast Transient Response
■ Fault Protection Circuitry
Thermal Shutdown
Overcurrent Protection
Safe Area Protection
Package Options
3L TO-220
Tab (V
OUT
)
CS5207-2
7A, 1.5V Fixed Linear Regulator
1
CS5207-2
The CS5207-2 provides 7A at 1.5V
with an accuracy of ± 2%.
The regulator is intended for use as
an active termination for the GTL
bus on Intel based motherboards.
The fast loop response and low
dropout voltage make these regulators 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 1V
depending on the output current
level. The maximum quiescent current is only 10mA at full load.
The regulators are fully protected
against overload conditions with
protection circuitry for Safe
Operating Area (SOA), overcurrent
and thermal shutdown.
The CS5207-2 is available in TO-220
packages.
Block Diagram
1 Gnd
2V
OUT
(Tab)
3V
IN
Description
Absolute Maximum Ratings
Supply Voltage, V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17V
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
ESD Damage Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV
A Company
¨
Rev. 6/12/98
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
V
IN
V
OUT
Thermal
Shutdown
Bandgap
-
+
Amplifier
Error
Output
Current
Limit
Gnd
Page 2
2
CS5207-2
Typical Performance Characteristics
Dropout Voltage vs. Output Current
Output Voltage vs. Temperature
Electrical Characteristics: C
IN
= 10µF, C
OUT
= 22µF Tantalum, V
IN
Ð V
OUT
=3V, VIN² 10V, 0¡C ² TA ² 70¡C, TJ² +150¡C,
unless otherwise specified, I
full load
= 7A.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Package Pin Description
PACKAGE PIN # PIN SYMBOL FUNCTION
■ Fixed Output Voltage
CS5207-2 V
IN
Ð V
OUT
= 1.65V; 1.47 1.50 1.53 V
(Notes 1 and 2) 0² I
OU T
² 7A (-2%) (+2%)
Line Regulation 1.65V ² VINÐV
OUT
² 6V; I
OUT
= 10mA 0.04 0.20 %
Load Regulation (Notes 1 and 2) V
IN
Ð V
OUT
= 1.65V; 10mA ² I
OUT
² 7A 0.08 0.40 %
Dropout Voltage (Note 3) I
OUT
= 7A 1.42 1.65 V
Current Limit V
IN
Ð V
OUT
= 3V; TJ³ 25¡C 7.1 8.5 A
V
IN
Ð V
OUT
= 12V 1.0 A
Quiescent Current V
IN
² 9V; I
OUT
= 10mA 5.0 10.0 mA
Thermal Regulation 30ms pulse; TA = 25¡C 0.003 %/W
Ripple Rejection f = 120Hz; I
OUT
= 7A 80 dB
Temperature Stability 0.5 %
RMS Output Noise (%V
OUT
) 10Hz ² f ² 10kHz 0.003 %V
OUT
Thermal Shutdown 150 180 ¡C
Thermal Shutdown Hysteresis 25 ¡C
Note 1: Load regulation and output voltage are measured at a constant junction temperature by low duty cycle pulse testing. Changes in out-
put voltage due to thermal gradients or 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.
3L TO-220
1 Gnd Ground connection.
2V
OUT
Regulated output voltage (case).
3V
IN
Input voltage.
1.55
1.50
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
Dropout Voltage (V)
1.00
0.95
0.90
0.85
T
= 25°C
CASE
0.80
0.75
0.70
01 2 3 4 5 6
T
= 0°C
CASE
Output Current (A)
T
= 125°C
CASE
7
0.10
0.08
0.06
0.04
0.02
0.00
-0.02
-0.04
-0.06
Output Voltage Deviation (%)
-0.08
-0.10
-0.12
20 30 40 50 60 70 80 90 100 110 120
0 10 130
TJ (°C)
Page 3
CS5207-2
3
Load Regulation vs. Output Current Ripple Rejection vs Frequency
Typical Performance Characteristics: continued
the CS5207-2 linear regulator provides a fixed 1.5V output at currents up to 7A. The regulator is protected
against short circuit, and includes thermal shutdown and
safe area protection (SOA) circuitry. The SOA protection
circuitry decreases the maximum available output current
as the input-output differential voltage increases.
The CS5207-2 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 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 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 manufacturersÕ data sheet provides this information.
A 22µF tantalum capacitor will work for most applications,
but with high current regulators such as the CS5207-2 the
transient response and stability improve with higher values of capacitor. 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:
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 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 CS5207-2, 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 1 is recommended.
Figure 1. Protection diode scheme for fixed output regulators.
Protection Diodes
Stability Considerations
Applications Information
0.200
0.175
0.150
0.125
0.100
0.075
0.050
Output Voltage Deviation (%)
0.025
0.000
01 2 3 4 5
Output Current (A)
T
= 125°C
CASE
T
= 25°C
CASE
T
= 0°C
CASE
67
100.0
90.0
80.0
70.0
60.0
50.0
40.0
Ripple Rejection (dB)
30.0
20.0
10.0
0.0
T
I
OUT
(V
V
1
10
CASE
= 7A
Ð V
IN
RIPPLE
= 25°C
10
) = 3V
OUT
= 1.6V
2
PP
3
10
Frequency (Hz)
4
10
5
10
IN4002 (optional)
V
IN
C
1
V
IN
CS5207-2
Gnd
V
OUT
V
OUT
C
2
Page 4
4
Since the CS5207-2 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 fixed regulators should be connected as shown in Figure 2.
Figure 2. Conductor parasitic resistance effects can be minimized with
the above grounding scheme for fixed output regulators.
The CS5207-2 includes thermal shutdown and safe operating area 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 V
OUT
on the CS5207-2, 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. Maximum Ambient Temperature T
A
(¡C)
2. Power dissipation P
D
(Watts)
3. Maximum junction temperature T
J
(¡C)
4. Thermal resistance junction to ambient R
QJA
(C/W)
These four are related by the equation
TJ= TA+ PD´ 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 maximum power dissipation for a regulator is:
P
D(max)
={V
IN(max)ÐVOUT(min)}IOUT(max)+VIN(max)IQ
(2)
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 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 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 Heat Sink, R
QCS
(¡C/W)
3. Thermal Resistance of the Heat Sink to the ambient air,
R
QSA
(¡C/W)
These are connected by the equation:
R
QJA
= R
QJC
+ R
QCS
+ R
QSA
(3)
The value for R
QJA
is calculated using equation (3) and the
result can be substituted in equation (1).
R
QJC
is 1.6¡C/Watt for the CS5207-2. For a high current
regulator such as the CS5207-2 the majority of the heat is
generated in the power transistor section. The value for
R
QSA
depends on the heat sink type, while R
QCS
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
R
QJA
can be calculated and the proper heat sink selected.
For further discussion on heat sink selection, see application note ÒThermal Management for Linear Regulators.Ó
Calculating Power Dissipation and Heat Sink Requirements
Output Voltage Sensing
Applications Information: continued
CS5207-2
conductor parasitic
resistance
R
V
IN
V
IN
CS5207-2
Gnd
V
OUT
C
R
LOAD
Page 5
5
Part Number Type Description
CS5207-2GT3 7A, 1.5V output 3 L TO-220 Straight
Ordering Information
Rev. 6/12/98
Package Specification
PACKAGE DIMENSIONS IN mm(INCHES)
3L
Thermal Data TO-220
R
QJC
typ 1.6 ûC/W
R
QJA
typ 50 ûC/W
PACKAGE THERMAL DATA
Cherry Semiconductor Corporation reserves the right to
make changes to the specifications without notice. Please
contact Cherry Semiconductor Corporation for the latest
available information.
© 1999 Cherry Semiconductor Corporation
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)
CS5207-2
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