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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 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.
Features
s Output Current to 3A s Output Accuracy to 1.5% Over Temperature s Dropout Voltage (typical) 1.15V @ 3A s Fast Transient Response s Fault Protection Current Limit Thermal Shutdown
Application Diagram
Package Options
3L D2PAK
VIN 5V VOUT
Tab (VOUT)
CS5203-3
GND 100mF 5V 10mF 5V
3.3V @ 3A
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40C to 70C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150C Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-60C to 150C Lead Temperature Soldering Reflow (SMD styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 sec. max above 183C, 230C peak ESD Damage Threshold (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV
Electrical Characteristics: CIN = 10F, COUT = 22F Tantalum, VOUT + VDROPOUT < VIN < 7V, 0C TA 70C, TJ +150C,
unless otherwise specified, Ifull load = 3A. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s Fixed Output Voltage Output Voltage (Notes 1 and 2) Line Regulation Load Regulation (Notes 1 and 2) Dropout Voltage (Note 3) Current Limit Quiescent Current Thermal Regulation (Note 4) Ripple Rejection (Note 4) Thermal Shutdown (Note 5) Thermal Shutdown Hysteresis (Note 5) VINVOUT=1.5V; 0IOUT3A 2VVINVOUT3.7V; IOUT=10mA VINVOUT=2V; 10mAIOUT3A IOUT=3A VINVOUT=3V IOUT=10mA 30ms pulse; TA=25C f=120Hz; IOUT=3A; VINVOUT=3V; VRIPPLE=1VPP 150 3.1 3.250 (-1.5%) 3.300 0.02 0.04 1.15 4.6 6.0 0.002 80 180 25 210 10.0 0.020 3.350 (+1.5%) 0.20 0.4 1.4 V % % V A mA %/W dB 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 1/4O 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 2 3 Gnd VOUT VIN Ground connection. Regulated output voltage (case). 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 Reference Voltage Deviation (%) 1.15 1.10 Dropout Voltage (V) 1.05 1.00 0.95 0.90 0.85 0.80 0.75 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 TCASE = 25C
TCASE
+0.3
+0.2
= 0C
+0.1
0
TCASE = 125C
-0.1
-0.2 -0.3 0 30 60 TJ (C) 90 120
Dropout Voltage vs. Output Current
Output Voltage Deviation vs Temperature
0.16
85 75
Output Voltage Deviation (%)
0.12
Ripple Rejection (dB)
65 55 45 35 25
0.08
TCASE = 125C TCASE = 25C
0.04
TCASE = 25C IOUT = 1A (VIN VOUT) = 3V VRIPPLE = 1.0VPP
TCASE = 0C
0.000
0 1.5 Output Current (A) 3
15
101 102 103 104 105 106
Frequency (Hz)
Load Regulation vs. Output Current
Ripple Rejection vs Frequency
3
CS5203-3
Typical Performance Characteristics: continued
6.00
+200 DVOUT 0 (mV)
5.00
4.00
ISC(A)
VIN = 5V VOUT = 3.3V CIN = 100mF COUT = 10mF Tantalum
-200
3.00 2.00
3 2 I(A) 1 0 0
1.00 0.00
5 Time (ms)
10
1.0
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.
Stability Considerations Protection Diodes
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 manufacturersO data sheet provides this information. A 22F 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: AEV = AEI 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 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.
IN4002 VIN C1 VIN
(optional) VOUT VOUT
CS5203-3
C2 GND
Figure 1. Protection diode scheme for large output capacitors.
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 VIN VOUT
conductor parasitic resistance
PD(max)={VIN(max)VOUT(min)}IOUT(max)+VIN(max)IQ where VIN(max) is the maximum input voltage, VOUT(min) is the minimum output voltage,
(2)
CS5203-3
GND
RLOAD
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.
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
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. 1. Thermal Resistance of the junction to case, RQJC (C/W) 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) These are connected by the equation: RQJA = RQJC + RQCS + RQSA (3)
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. 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. The thermal characteristics of an IC depend on the following four factors: 1. Maximum Ambient Temperature TA (C) 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 value for RQJA is calculated using equation (3) and the result can be substituted in equation (1). The value for RQJC is 3.5uC/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 OThermal Management for Linear Regulators.O
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 DIMENSIONS IN mm(INCHES) PACKAGE THERMAL DATA
Thermal Data RQJC typ RQJA typ
3L D2PAK 3.5 10 - 50*
uC/W uC/W
*Depending on thermal properties of substrate. RQJA = RQJC + RQCA
3 Lead D2PAK (DP)
10.31 (.406) 10.05 (.396) 1.68 (.066) 1.40 (.055)
1.40 (.055) 1.14 (.045)
8.53 (.336) 8.28 (.326) 15.75 (.620) 14.73 (.580) 2.74(.108) 2.49(.098) 1.40 (.055) 1.14 (.045) 0.91 (.036) 0.66 (.026) 2.54 (.100) REF .254 (.010) REF 2.79 (.110) 2.29 (.090)
4.57 (.180) 4.31 (.170)
0.10 (.004) 0.00 (.000)
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
(c) 1999 Cherry Semiconductor Corporation

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