CS5207-3 CS5207-3 7A, 3.3V Fixed Linear Regulator Description Features The CS5207-3 linear regulator provides 7A at 3.3V with an accuracy of ±2%. depending on the output current level. The maximum quiescent current is only 10mA at full load. The regulator is intended for use as 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 regulator is fully protected against overload conditions with protection circuitry for Safe Operating Area (SOA), overcurrent and thermal shutdown. The CS5207-3 is available in 3 lead D2PAK and TO-220 packages. The circuit is designed to operate with dropout voltages as low as 1V ■ Output Current to 7A ■ Output Voltage Trimmed to ±2% ■ Dropout Voltage 1.4V @ 7A ■ Fast Transient Response ■ Fault Protection Circuitry Thermal Shutdown Overcurrent Protection Safe Area Protection Absolute Maximum Ratings Supply Voltage, VCC .........................................................................................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 Reflow (SMD styles only) .............60 sec. max above 183¡C, 230¡C peak Package Options 3L TO-220 Tab (VOUT) Block Diagram V OUT V IN 1 2 3 1 Output Current Limit Thermal Shutdown - + Gnd VOUT (Tab) VIN 3L D2PAK Tab (VOUT) Error Amplifier Bandgap 1 2 3 Gnd Gnd VOUT (Tab) VIN 1 Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: [email protected] Web Site: www.cherry-semi.com Rev. 10/2/97 1 A ¨ Company CS5207-3 Electrical Characteristics: CIN = 10µF, COUT = 22µF Tantalum, VIN Ð VOUT=3V, VIN ² 15V, 0¡C ² TA ² 70¡C, TJ ² +150¡C, unless otherwise specified, Ifull load = 7A. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 3.234 (-2%) 3.300 3.366 (+2%) V ■ 3.3V Fixed Output Voltage CS5207-3 (Notes 1 and 2) VINÐVOUT=1.6V; 10mA²IOUT²7A Line Regulation 1.6V²VINÐVOUT²6V; IOUT=10mA 0.04 0.20 % Load Regulation (Notes 1 and 2) VINÐVOUT=1.6V; 10mA²IOUT²7A 0.13 0.5 % 1.4 1.55 Dropout Voltage (Note 3) IOUT=7A Current Limit VINÐVOUT=3V; TJ ³ 25¡C VINÐVOUT=9V Quiescent Current VIN²9V; IOUT=10mA 7.1 8.5 1.0 V A A 5.0 10.0 mA Thermal Regulation 30ms pulse; TA=25¡C 0.003 %W Ripple Rejection f=120Hz; IOUT=7A 80 dB 0.5 % 0.003 %VOUT 180 ¡C 25 ¡C Temperature Stability 10Hz²f²10kHz; TA=25¡C RMS Output Noise Thermal Shutdown 150 Thermal Shutdown Hysteresis 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 1/4Ó 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 & 3L D2PAK 1 Gnd Ground connection. 2 VOUT Regulated output voltage (case). 3 VIN Input voltage. 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 = 25°C 0.80 0.75 0.70 0 1 0.10 0.08 Output Voltage Deviation (%) Dropout Voltage (V) Typical Performance Characteristics TCASE = 0°C TCASE = 125°C 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 6 7 0 10 20 30 40 50 60 70 TJ (°C) Output Voltage vs. Temperature Dropout Voltage vs. Output Current 2 80 90 100 110 120 130 CS5207-3 Typical Performance Characteristics: continued 0.200 100.0 90.0 Ripple Rejection (dB) Output Voltage Deviation (%) 0.175 0.150 0.125 TCASE = 125°C 0.100 0.075 TCASE = 25°C 70.0 60.0 50.0 TCASE = 25°C IOUT = 7A (VIN Ð VOUT) = 3V VRIPPLE = 1.6VPP 40.0 30.0 0.050 20.0 TCASE = 0°C 0.025 80.0 10.0 0.000 0 1 2 3 4 5 0.0 6 7 101 102 103 Output Current (A) 104 105 Frequency (Hz) Load Regulation vs. Output Current Ripple Rejection vs. Frequency Applications Information The CS5207-3 linear regulator provides a fixed 3.3V 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 CS5207-3 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. work should be as close as possible to the load for the best results. 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 CS5207-3 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 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 CS5207-3 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: IN4002 VIN VOUT VIN C1 (optional) CS5207-3 VOUT C2 Gnd Figure 1. Protection diode scheme for fixed output regulator. Output Voltage Sensing ÆV = ÆI ´ ESR Since the CS5207-3 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. Best load regulation occurs when the regulator is connected to the load as shown in Figure 2. 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 net3 CS5207-3 Applications Information: continued VIN VOUT VIN RC determine RQJA, the total thermal resistance between the junction and the surrounding air. conductor parasitic resistance CS5207-3 1. Thermal Resistance of the junction to case, RQJC (¡C/W) 2. Thermal Resistance of the case to Heat Sink, RQCS (¡C/W) RLOAD 3. Thermal Resistance of the Heat Sink to the ambient air, RQSA (¡C/W) Gnd These are connected by the equation: RQJA = RQJC + RQCS + RQSA Figure 2. Grounding scheme for the output regulator to minimize parasitics. The value for RQJA is calculated using equation (3) and the result can be substituted in equation (1). RQJC is 1.6¡C/Watt for the CS5207-3. For a high current regulator such as the CS5207-3, 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 Calculating Power Dissipation and Heat Sink Requirements The CS5207-3 linear regulator includes thermal shutdown and safe operating area circuitry to protect the device. High power regulators such as this 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 CS5207-3, 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 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)ÐVOUT(min)}IOUT(max)+VIN(max)IQ (3) (2) where VIN(max) is the maximum input voltage, VOUT(min) is the minimum output voltage, 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 4 CS5207-3 Package Specification PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA 3 Lead D2PAK (DP) 10.31 (.406) 10.05 (.396) 3L TO-220 1.6 50 Thermal Data RQJC typ RQJA typ 1.40 (.055) 1.14 (.045) 3L D2PAK 1.6 10 - 50* ûC/W ûC/W *Depending on thermal properties of substrate. RQJA = RQJC + RQCA 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 4.57 (.180) 4.31 (.170) .254 (.010) REF 0.10 (.004) 0.00 (.000) 3 Lead TO-220 (T) Straight 4.83 (.190) 4.06 (.160) 10.54 (.415) 9.78 (.385) 6.55 (.258) 5.94 (.234) 1.40 (.055) 1.14 (.045) 3.96 (.156) 3.71 (.146) 2.87 (.113) 2.62 (.103) 14.99 (.590) 14.22 (.560) 1.52 (.060) 1.14 (.045) 14.22 (.560) 13.72 (.540) 6.17 (.243) REF 1.40 (.055) 1.14 (.045) 1.02 (.040) 0.63 (.025) 0.56 (.022) 0.38 (.014) 2.79 (.110) 2.29 (.090) 5.33 (.210) 4.83 (.190) 2.92 (.115) 2.29 (.090) Ordering Information Part Number CS5207-3GT3 CS5207-3GDP3 CS5207-3GDPR3 Rev. 10/2/97 Description 3L TO-220 Straight 3L D2PAK 3L 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. 5 © 1999 Cherry Semiconductor Corporation