CS5210-1 10 A LDO 3-Pin Adjustable Linear Regulator The CS5210–1 linear regulator provides 10 A at adjustable voltages from 1.25 V to 4.5 V. This adjustable device requires two external resistors to set the output voltage and provide the minimum load current for proper regulation. 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 operate with dropout voltages as low as 1.05 V at 10 A. The regulator is protected against overload conditions with overcurrent and thermal shutdown protection circuitry. The regulator is available in a TO–220 package. Features • 1.25 V to 4.5 V VOUT at 10 A • Dropout Voltage < 1.05 V @ 10 A • 2.0% Trimmed Reference • Fast Transient Response • Thermal Shutdown • Current Limit • Short Circuit Protection 2 3 Tab = VOUT Pin 1. Adjust 2. VOUT 3. VIN 3.3 V @ 10 A 1 CS5210–1 A WL, L YY, Y WW, W 124 100 µF Load 0.1 µF 1 CS5210–1 AWLYWW VOUT Adj TO–220 THREE LEAD T SUFFIX CASE 221A PIN CONNECTIONS AND MARKING DIAGRAMS 5.0 V VIN http://onsemi.com 200 300 µF = Assembly Location = Wafer Lot = Year = Work Week ORDERING INFORMATION Device CS5210–1GT3 Package Shipping TO–220* 50 Units/Rail *TO–220 is 3–pin, straight leaded. Figure 1. Applications Diagram Semiconductor Components Industries, LLC, 2001 February, 2001 – Rev. 4 1 Publication Order Number: CS5210–1/D CS5210–1 ABSOLUTE MAXIMUM RATINGS* Parameter Value Unit 6.0 V Operating Ambient Temperature Range 0 ≤ TA ≤ 70 °C Operating Junction Temperature Range 0 ≤ TJ ≤ 150 °C Storage Temperature Range –65 to +150 °C 260 Peak °C 2.0 kV Input Voltage Lead Temperature Soldering: Wave Solder (through hole styles only) Note 1. ESD Damage Threshold 1. 10 second maximum. *The maximum package power dissipation must be observed. ELECTRICAL CHARACTERISTICS ( 0°C ≤ TA ≤ 70°C, 0°C ≤ TJ ≤ 150°C, VAdj = 0 V, unless otherwise specified.) Characteristic Test Conditions Min Typ Max Unit 1.227 (–2.0%) 1.253 1.278 (+2.0%) V Adjustable Output Voltage Reference Voltage VIN = 2.75 V to 5.5 V, IOUT = 10 mA to 10 A Line Regulation VIN = 2.75 V to 5.5 V, IOUT = 10 mA – 0.02 0.20 % Load Regulation VIN = 2.75 V, IOUT = 10 mA to 10 A – 0.04 0.50 % Minimum Load Current (Note 2.) VIN = 5.0 V, ∆VOUT = +2.0% – 5.0 10 mA Adjust Pin Current VIN = 2.75 V, IOUT = 10 mA – 70 120 µA Current Limit VIN = 2.75 V, ∆VOUT = –2.0% 10.1 12 – A Short Circuit Current VIN = 2.75 V, VOUT = 0 V 8.0 10 – A Ripple Rejection (Note 3.) VIN = 3.25 V Avg, VRIPPLE = 1.0 VP–P @ 120 Hz, IOUT = 4.0 A, CAdj = 0.1 µF; COUT = 22 µF 60 80 – dB Thermal Regulation (Note 3.) 30 ms Pulse, TA = 25°C – 0.002 – %/W Dropout Voltage (Minimum VIN–VOUT) (Note 4.) IOUT = 100 mA IOUT = 1.0 A IOUT = 2.75 A IOUT = 4.0 A IOUT = 10 A – – – – – 0.92 0.93 0.94 0.95 1.03 1.15 1.15 1.15 1.15 1.40 V V V V V RMS Output Noise Freq = 10 Hz to 10 kHz, TA = 25°C – 0.003 – %VOUT Temperature Stability – – 0.5 – % Thermal Shutdown (Note 5.) – 150 180 210 °C Thermal Shutdown Hysteresis (Note 5.) – – 25 – °C 2. The minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor divider used to set the output voltage is selected to meet the minimum load current requirement. 3. This parameter is guaranteed by design and is not 100% production tested. 4. Dropout voltage is defined as the minimum input/output voltage differential required to maintain 2.0% regulation. 5. This parameter is guaranteed by design, but not parametrically tested in production. However, a 100% thermal shutdown functional test is performed on each part. http://onsemi.com 2 CS5210–1 PACKAGE PIN DESCRIPTION Package Pin Number TO–220 Pin Symbol Function 1 Adjust This pin is connected to the low side of the internally trimmed 2.0% bandgap reference voltage and carries a bias current of about 70 µA. A resistor divider from Adj to VOUT and from Adj to ground sets the output voltage. Also, transient response can be improved by adding a small bypass capacitor from this pin to ground. 2 VOUT This pin is connected to the emitter of the power pass transistor and provides a regulated voltage capable of sourcing 10 A of current. 3 VIN This is the supply voltage for the regulator. For the device to regulate, this voltage should be between 1.2 V and 1.40 V (depending on the output current) greater than the output voltage. VIN BIAS and TSD – EA + VREF + IA – VOUT Adj Figure 2. Block Diagram TYPICAL PERFORMANCE CHARACTERISTICS 90 IO = 10 mA Adjust Pin Current (µA) Adjust Pin Current (µA) 85 80 75 70 65 60 0 10 20 30 73.00 72.80 72.60 72.40 72.20 72.00 71.80 71.60 71.40 71.20 71.00 70.80 70.60 70.40 70.20 70.00 40 50 60 70 80 90 100 110 120 130 0 1 2 3 4 5 6 7 8 TCASE (°C) IOUT (A) Figure 3. Adjust Pin Current Voltage vs. Temperature Figure 4. Adjust Pin vs. IOUT http://onsemi.com 3 9 10 CS5210–1 0.350 0.100 IO = 10 mA VIN = 2.75 V Output Voltage Deviation (%) Output Voltage Deviation (%) 0.075 0.050 0.025 0.000 –0.025 –0.050 –0.075 –0.100 –0.125 –0.150 0.300 TCASE = 125°C 0.250 0.200 TCASE = 25°C 0.150 0.100 TCASE = 0°C 0.050 0.000 0 10 20 30 40 50 60 70 80 90 100 110 120 130 0 1 2 3 4 5 6 7 8 9 TJ (°C) Output Current (A) Figure 5. Reference Voltage vs. Temperature Figure 6. Load Regulation vs. Output Current 10 1.250 90 1.000 70 VDROPOUT (mV) Ripple Rejection (dB) 80 60 50 VIN – VOUT = 2.0 V 40 IOUT = 4.0 A VRIPPLE = 1.0 VPP COUT = 22 µF CAdj = 0.1 µF 30 20 10 101 102 103 0.500 0.250 104 105 0.000 106 0 1 2 3 4 5 6 7 8 Frequency (Hz) Output Current (A) Figure 7. Ripple Rejection vs. Frequency Figure 8. VDROPOUT vs. IOUT 1.00 18 0.98 Minimum Load Current (mA) 20 16 Output Current (A) 0.750 14 12 10 8 6 4 2 9 10 0.96 0.94 TCASE = 25°C TCASE = 125°C 0.92 0.90 0.88 0.86 0.84 TCASE = 0°C 0.82 0 0.80 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 1 2 3 4 VIN – VOUT (V) VIN – VOUT (V) Figure 9. Short Circuit vs. VIN – VOUT Figure 10. Minimum Load Current vs. VIN – VOUT http://onsemi.com 4 5 CS5210–1 APPLICATION NOTES THEORY OF OPERATION The CS5210–1 linear regulator has an absolute maximum specification of 6.0 V for the voltage difference between VIN and VOUT. However, the IC may be used to regulate voltages in excess of 6.0 V. The main considerations in such a design are power–up and short circuit capability. In most applications, ramp–up of the power supply to VIN is fairly slow, typically on the order of several tens of milliseconds, while the regulator responds in less than one microsecond. In this case, the linear regulator begins charging the output capacitor as soon as the VIN to VOUT differential is large enough that the pass transistor conducts current. VOUT is essentially at ground, and VIN is on the order of several hundred millivolts, so the pass transistor is in dropout. As VIN increases, the pass transistor will remain in dropout, and current is passed to the load until VOUT is in regulation. Further increase in VIN brings the pass transistor out of dropout. The result is that the output voltage follows the power supply ramp–up, staying in dropout until the regulation point is reached. In this manner, any output voltage may be regulated. There is no theoretical limit to the regulated voltage as long as the VIN to VOUT differential of 6.0 V is not exceeded. However, the maximum ratings of the IC will be exceeded in a short circuit condition. Short circuit conditions will result in the immediate operation of the pass transistor outside of its safe operating area. Over–voltage stresses will then cause destruction of the pass transistor before overcurrent or thermal shutdown circuitry can become active. Additional circuitry may be required to clamp VIN to VOUT differential to less than 6.0 V if failsafe operation is required. One possible clamp circuit is illustrated in Figure 12; however, the design of clamp circuitry must be done on an application by application basis. Care must be taken to ensure the clamp actually protects the design. Components used in the clamp design must be able to withstand the short circuit conditions indefinitely while protecting the IC. The CS5210–1 linear regulator has a composite PNP–NPN output stage that requires an output capacitor for stability. A detailed procedure for selecting this capacitor is included in the Stability Considerations section. ADJUSTABLE OPERATION Design Guidelines This LDO adjustable regulator has an output voltage range of 1.25 V to 4.5 V. An external resistor divider sets the output voltage as shown in Figure 11. The regulator’s voltage sensing error amplifier maintains a fixed 1.25 V reference between the output pin and the adjust pin. A resistor divider network R1 and R2 causes a fixed current to flow to ground. This current creates a voltage across R2 that adds to the 1.25 V across R1 and sets the overall output voltage. The adjust pin current (typically 50 µA) also flows through R2 and adds a small error that should be taken into account if precise adjustment of VOUT is necessary. The output voltage is set according to the formula: R R2 VOUT VREF 1 R2 IAdj R1 The term IAdj × R2 represents the error added by the adjust pin current. R1 is chosen so that the minimum load current is at least 10 mA. R1 and R2 should be of the same composition for best tracking over temperature. The divider resistors should be placed as close to the IC as possible and connected to the output with a seperate metal trace. VIN VOUT CS5210–1 Adj R1 EXTERNAL SUPPLY R2 Figure 11. While not required, a bypass capacitor connected between the adjust pin and ground will improve transient response and ripple rejection. A 0.1 µF tantalum capacitor is recommended for “first cut” design. Value and type may be varied to optimize performance vs price. VIN VOUT VAdj Figure 12. http://onsemi.com 5 CS5210–1 STABILITY CONSIDERATIONS If the calculated current is greater than or equal to the typical short circuit current value provided in the specifications, serious thought should be given to including a protection diode. The output 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 manufacturer’s data sheet provides this information. A 300 µF tantalum capacitor will work for most applications, but with high current regulators such as the CS5210–1 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: VIN CS5210–1 Adj Figure 13. Current Limit The internal current limit circuit limits the output current under excessive load conditions and protects the regulator. V I ESR Short Circuit Protection 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 transient load conditions. The output capacitor network should be as close to the load as possible for the best results. The device includes foldback short circuit current limit that clamps the output current at approximately two amperes less than its current limit value. Thermal Shutdown The thermal shutdown circuitry is guaranteed by design to become activated above a die junction temperature of 150°C and to shut down the regulator output. This circuitry includes a thermal hysteresis circuit with 25°C of typical hysteresis, thereby allowing the regulator to recover from a thermal fault automatically. 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 CS5210–1 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 13 is recommended. A rule of thumb useful in determining if a protection diode is required is to solve for current I VOUT Calculating Power Dissipation and Heat Sink Requirements High power regulators such as the CS5210–1 usually operate at high junction temperatures. Therefore, it is important to calculate the power dissipation and junction temperatures accurately to ensure that an adequate heat sink is used. Since the package tab is connected to VOUT on the CS5210–1, electrical isolation may be required for some applications. Also, as with all high power packages, thermal compound is necessary to ensure proper heat flow. For added safety, this high current LDO includes an internal thermal shutdown circuit The thermal characteristics of an IC depend on the following four factors. Junction temperature, ambient temperature, die power dissipation, and the thermal resistance from the die junction to ambient air. The maximum junction temperature can be determined by: CV T where: I is the current flow out of the load capacitance when VIN is shorted, C is the value of the load capacitance, V is the output voltage, and T is the time duaration required for VIN to transition from high to being shorted. TJ(max) TA(max) PD(max) RJA http://onsemi.com 6 CS5210–1 RJA RJC RCS RSA 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: RΘJC is rated @ 1.4°C/W for the CS5210–1. For a high current regulator such as the CS5210–1 the majority of heat is generated in the power transistor section. The value for RΘSA depends on the heat sink type, while the RΘCS 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 RΘJA can be calculated and the proper heat sink selected. For further discussion on heat sink selection, see application note “Thermal Management for Linear Regulators,” document number SR006AN/D, available through the Literature Distribution Center or via our website at http://onsemi.com. PD(max) (VIN(max) VOUT(min))IOUT(max) VIN(max) IIN(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 the total thermal resistance between the die junction and the surrounding air, RΘJC. This total thermal resistance is comprised of three components. These resistive terms are measured from junction to case (RΘJC), case to heat sink (RΘCS), and heat sink to ambient air (RΘSA). The equation is: http://onsemi.com 7 CS5210–1 PACKAGE DIMENSIONS TO–220 THREE LEAD T SUFFIX CASE 221A–09 ISSUE AA SEATING PLANE –T– B C F T S 4 DIM A B C D F G H J K L N Q R S T U V Z A Q 1 2 3 U H K Z L R V NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION Z DEFINES A ZONE WHERE ALL BODY AND LEAD IRREGULARITIES ARE ALLOWED. J G D N INCHES MIN MAX 0.570 0.620 0.380 0.405 0.160 0.190 0.025 0.035 0.142 0.147 0.095 0.105 0.110 0.155 0.018 0.025 0.500 0.562 0.045 0.060 0.190 0.210 0.100 0.120 0.080 0.110 0.045 0.055 0.235 0.255 0.000 0.050 0.045 ----0.080 MILLIMETERS MIN MAX 14.48 15.75 9.66 10.28 4.07 4.82 0.64 0.88 3.61 3.73 2.42 2.66 2.80 3.93 0.46 0.64 12.70 14.27 1.15 1.52 4.83 5.33 2.54 3.04 2.04 2.79 1.15 1.39 5.97 6.47 0.00 1.27 1.15 ----2.04 PACKAGE THERMAL DATA Parameter TO–220 THREE LEAD Unit RΘJC Typical 1.4 °C/W RΘJA Typical 50 °C/W ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. 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