CHERRY CS5203-3

CS5203-3
CS5203-3
3A, 3.3V Fixed Linear Regulator
Description
The CS5203-3 linear regulator
provides a 3.3V reference at 3A
with an output voltage accuracy
of ±1.5%.
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 provide 3A of output current with
dropout voltages of less than
Features
1.15V. The maximum quiescent
current is only 10mA at full
load. Device protection includes
overcurrent and thermal shutdown.
The CS5203-3 is pin compatible
with the LT1085 family of linear
regulators.
The regulator is available in a
surface mount D2 package.
■ Output Current to 3A
■ Output Accuracy to ±1.5%
Over Temperature
■ Dropout Voltage (typical)
1.15V @ 3A
■ Fast Transient Response
■ Fault Protection
Current Limit
Thermal Shutdown
Application Diagram
Package Options
3L D2PAK
5V
Tab (VOUT)
VOUT
VIN
3.3V
@ 3A
CS5203-3
GND
10mF
5V
100mF
5V
1
CS5203 -3
1 Gnd
2 VOUT (Tab)
3 VIN
Consult factory for other package
options.
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
Rev. 6/3/98
1
A
¨
Company
CS5203-3
Absolute Maximum Ratings
Supply Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7V
Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40¡C to 70¡C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150¡C
Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-60¡C to 150¡C
Lead Temperature Soldering
Reflow (SMD styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 sec. max above 183¡C, 230¡C peak
ESD Damage Threshold (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV
Electrical Characteristics: CIN = 10µF, COUT = 22µF Tantalum, VOUT + VDROPOUT < VIN < 7V, 0¡C ² TA ² 70¡C, TJ ² +150¡C,
unless otherwise specified, Ifull load = 3A.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
3.250
(-1.5%)
3.300
3.350
(+1.5%)
V
■ Fixed Output Voltage
Output Voltage
(Notes 1 and 2)
VINÐVOUT=1.5V;
0²IOUT²3A
Line Regulation
2V²VINÐVOUT²3.7V; IOUT=10mA
0.02
0.20
%
Load Regulation
(Notes 1 and 2)
VINÐVOUT=2V; 10mA²IOUT²3A
0.04
0.4
%
Dropout Voltage (Note 3)
IOUT=3A
1.15
1.4
V
Current Limit
VINÐVOUT=3V
3.1
4.6
A
Quiescent Current
IOUT=10mA
6.0
10.0
mA
Thermal Regulation (Note 4)
30ms pulse; TA=25¡C
0.002
0.020
%/W
Ripple Rejection (Note 4)
f=120Hz; IOUT=3A; VINÐVOUT=3V;
VRIPPLE=1VPP
80
Thermal Shutdown (Note 5)
150
Thermal Shutdown Hysteresis
(Note 5)
180
25
dB
210
¡C
¡C
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: Guaranteed by design, not tested in production.
Note 5: Thermal shutdown is 100% functionally tested in production.
Package Pin Description
PACKAGE PIN #
PIN SYMBOL
FUNCTION
D2PAK
1
Gnd
Ground connection.
2
VOUT
Regulated output voltage (case).
3
VIN
Input voltage.
2
CS5203-3
Block Diagram
V OUT
V IN
Output
Current
Limit
Thermal
Shutdown
-
+
Error
Amplifier
Bandgap
Reference
Gnd
Typical Performance Characteristics
1.20
+0.3
Reference Voltage Deviation (%)
1.15
Dropout Voltage (V)
1.10
1.05
TCASE
1.00
= 0°C
0.95
0.90
TCASE = 25°C
TCASE = 125°C
0.85
+0.2
+0.1
0
-0.1
-0.2
0.80
0.75
-0.3
0.00 0.30 0.60
0.90 1.20 1.50 1.80 2.10
Output Current (A)
2.40 2.70 3.00
0
60
30
90
120
TJ (°C)
Output Voltage Deviation vs Temperature
Dropout Voltage vs. Output Current
0.16
85
Ripple Rejection (dB)
Output Voltage Deviation (%)
75
0.12
0.08
TCASE = 125°C
TCASE = 25°C
65
55
TCASE = 25°C
IOUT = 1A
(VIN Ð VOUT) = 3V
VRIPPLE = 1.0VPP
45
35
0.04
25
TCASE = 0°C
15
0.000
0
1.5
Output Current (A)
3
101
102
103
104
Frequency (Hz)
Load Regulation vs. Output Current
Ripple Rejection vs Frequency
3
105
106
CS5203-3
Typical Performance Characteristics: continued
6.00
+200
5.00
DVOUT 0
(mV)
4.00
ISC(A)
-200
3
VIN = 5V
VOUT = 3.3V
CIN = 100mF
COUT = 10mF Tantalum
2
I(A)
3.00
2.00
1.00
1
0.00
0
0
5
Time (ms)
1.0
10
1.50
2.0
2.5
3.0
3.5
VIN-VOUT (V)
Transient Response
Short Circuit Current vs. VIN - VOUT
Applications Information
The CS5203-3 linear regulator provides a fixed 3.3V output voltage at currents up to 3A. The regulator is protected against overcurrent conditions and includes thermal
shutdown.
The CS5203-3 has a composite PNP-NPN output transistor
and requires an output capacitor for stability.
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 CS5203-3 linear 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 1 is recommended.
Stability Considerations
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 are 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 CS5203-3 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:
IN4002
VIN
VOUT
VIN
C1
(optional)
VOUT
CS5203-3
C2
GND
ÆV = ÆI ´ ESR
Figure 1. Protection diode scheme for large output capacitors.
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.
Output Voltage Sensing
Since the CS5203-3 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 regulator
should be connected as shown in figure 2.
4
CS5203-3
Applications Information: continued
The maximum power dissipation for a regulator is:
RC
VIN
conductor
parasitic resistance
PD(max)={VIN(max)ÐVOUT(min)}IOUT(max)+VIN(max)IQ
VOUT
VIN
CS5203-3
(2)
where
VIN(max) is the maximum input voltage,
RLOAD
VOUT(min) is the minimum output voltage,
GND
IOUT(max) is the maximum output current, for the application
IQ is 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.
Figure 2. Conductor parasitic resistance effects can be minimized with
the above grounding scheme for fixed output regulators.
Calculating Power Dissipation and Heat Sink Requirements
1. Thermal Resistance of the junction to case, RQJC (¡C/W)
The CS5203-3 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.
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)
The case is connected to VOUT on the CS5203-3, and electrical isolation may be required for some applications.
Thermal compound should always be used with high current regulators such as these.
These are connected by the equation:
RQJA = RQJC + RQCS + RQSA
(3)
The thermal characteristics of an IC depend on the following four factors:
The value for RQJA is calculated using equation (3) and the
result can be substituted in equation (1).
1. Maximum Ambient Temperature TA (¡C)
The value for RQJC is 3.5ûC/W. For a high current regulator such as the CS5203-3 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 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
RQJA 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
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 dissipation are determined by the design while the maximum
junction temperature and the thermal resistance depend
on the manufacturer and the package type.
5
CS5203-3
Package Specification
PACKAGE THERMAL DATA
PACKAGE DIMENSIONS IN mm(INCHES)
Thermal Data
RQJC
typ
RQJA
typ
3L
D2PAK
3.5
10 - 50*
ûC/W
ûC/W
*Depending on thermal properties of substrate. RQJA = RQJC + RQCA
3 Lead D2PAK (DP)
10.31 (.406)
10.05 (.396)
1.40 (.055)
1.14 (.045)
1.68 (.066)
1.40 (.055)
8.53 (.336)
8.28 (.326)
15.75 (.620)
14.73 (.580)
2.74(.108)
2.49(.098)
1.40 (.055)
1.14 (.045)
2.79 (.110)
2.29 (.090)
0.91 (.036)
0.66 (.026)
2.54 (.100) REF
.254 (.010) REF
0.10 (.004)
0.00 (.000)
4.57 (.180)
4.31 (.170)
Ordering Information
Part Number
Type
CS5203-3GDP3 3A, 3.3V output
CS5203-3GDPR3 3A, 3.3V output
Rev. 6/3/98
Description
3 L D2PAK
3 L D2PAK (tape & reel)
Cherry Semiconductor Corporation reserves the
right to make changes to the specifications without
notice. Please contact Cherry Semiconductor
Corporation for the latest available information.
6
© 1999 Cherry Semiconductor Corporation