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| CS5207-2 CS5207-2 7A, 1.5V Fixed Linear Regulator Description 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. Features s Output Current to 7A s Output Voltage Trimmed to 2% s Dropout Voltage 1.45V @ 7A s Fast Transient Response s Fault Protection Circuitry Thermal Shutdown Overcurrent Protection Safe Area Protection Absolute Maximum Ratings Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17V Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . .-40C to 70C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150C Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . .-60C to 150C Lead Temperature Soldering Wave Solder (through hole styles only) . . . . . .10 sec. max, 260C peak ESD Damage Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV Block Diagram Package Options 3L TO-220 Tab (VOUT) V OUT V IN 1 2 3 Gnd VOUT (Tab) VIN Output Current Limit Thermal Shutdown + Error Amplifier 1 Bandgap Gnd 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. 6/12/98 1 A Company CS5207-2 Electrical Characteristics: CIN = 10F, COUT = 22F Tantalum, VIN VOUT=3V, VIN 10V, 0C TA 70C, TJ +150C, unless otherwise specified, Ifull load = 7A. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT s Fixed Output Voltage CS5207-2 (Notes 1 and 2) Line Regulation Load Regulation (Notes 1 and 2) Dropout Voltage (Note 3) Current Limit Quiescent Current Thermal Regulation Ripple Rejection Temperature Stability RMS Output Noise (%VOUT) Thermal Shutdown Thermal Shutdown Hysteresis 10Hz f 10kHz 150 VIN VOUT = 1.65V; 0 IOU T 7A 1.65V VINVOUT 6V; IOUT = 10mA VIN VOUT = 1.65V; 10mA IOUT 7A IOUT = 7A VIN VOUT = 3V; TJ 25C VIN VOUT = 12V VIN 9V; IOUT = 10mA 30ms pulse; TA = 25C f = 120Hz; IOUT = 7A 7.1 1.47 (-2%) 1.50 0.04 0.08 1.42 8.5 1.0 5.0 0.003 80 0.5 0.003 180 25 10.0 1.53 (+2%) 0.20 0.40 1.65 V % % V A A mA %/W dB % %VOUT 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 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 1/4O from the bottom of the package. Note 3: Dropout voltage is a measurement of the minimum input/output differential at full load. Package Pin Description PACKAGE PIN # PIN SYMBOL FUNCTION 3L TO-220 1 2 3 Gnd VOUT VIN Ground connection. Regulated output voltage (case). Input voltage. Typical Performance Characteristics 1.55 1.50 1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 TCASE = 25C 0.80 0.75 0.70 0.10 0.08 Output Voltage Deviation (%) 6 7 0.06 0.04 0.02 0.00 -0.02 -0.04 -0.06 -0.08 -0.10 -0.12 2 3 4 Output Current (A) 5 0 10 20 30 40 50 60 70 80 90 100 110 120 130 TJ (C) Dropout Voltage (V) TCASE = 0C TCASE = 125C 0 1 Dropout Voltage vs. Output Current Output Voltage vs. Temperature 2 CS5207-2 Typical Performance Characteristics: continued 0.200 0.175 Output Voltage Deviation (%) Ripple Rejection (dB) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.150 0.125 TCASE = 125C 0.100 0.075 TCASE = 25C 0.050 0.025 0.000 0 1 2 3 4 5 6 7 Output Current (A) TCASE = 0C TCASE = 25C IOUT = 7A (VIN VOUT) = 3V VRIPPLE = 1.6VPP 0.0 101 102 103 Frequency (Hz) 104 105 Load Regulation vs. Output Current Ripple Rejection vs Frequency Applications Information 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. Stability Considerations 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. 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 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 manufacturersO data sheet provides this information. A 22F 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: 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 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 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. IN4002 VIN C1 VIN (optional) VOUT VOUT CS5207-2 C2 Gnd Figure 1. Protection diode scheme for fixed output regulators. 3 CS5207-2 Applications Information: continued Output Voltage Sensing 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) 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. 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. 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) VIN VIN VOUT RC conductor parasitic resistance CS5207-2 Gnd RLOAD Figure 2. Conductor parasitic resistance effects can be minimized with the above grounding scheme for fixed output regulators. These are connected by the equation: RQJA = RQJC + RQCS + RQSA (3) Calculating Power Dissipation and Heat Sink Requirements 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 VOUT 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 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). RQJC is 1.6C/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 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. The maximum power dissipation for a regulator is: 4 CS5207-2 Package Specification PACKAGE DIMENSIONS IN mm(INCHES) PACKAGE THERMAL DATA Thermal Data RQJC typ RQJA typ 3L TO-220 1.6 50 uC/W uC/W 3 Lead TO-220 (T) Straight 10.54 (.415) 9.78 (.385) 2.87 (.113) 2.62 (.103) 3.96 (.156) 3.71 (.146) 4.83 (.190) 4.06 (.160) 1.40 (.055) 1.14 (.045) 6.55 (.258) 5.94 (.234) 14.99 (.590) 14.22 (.560) 1.52 (.060) 1.14 (.045) 14.22 (.560) 13.72 (.540) 1.40 (.055) 1.14 (.045) 6.17 (.243) REF 1.02 (.040) 0.63 (.025) 2.79 (.110) 2.29 (.090) 5.33 (.210) 4.83 (.190) 0.56 (.022) 0.38 (.014) 2.92 (.115) 2.29 (.090) Ordering Information Part Number CS5207-2GT3 Rev. 6/12/98 Type 7A, 1.5V output Description 3 L TO-220 Straight Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. 5 (c) 1999 Cherry Semiconductor Corporation |
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