CS5253B-1GDPR5G

CS5253B−1 3.0 A LDO 5−Pin Adjustable Linear Regulator with Remote Sense Applications This new very low dropout linear regulator reduces total power dissipation in the application. To achieve very low dropout, the internal pass transistor is powered separately from the control circuitry. Furthermore, with the control and power inputs tied together, this device can be used in single supply configuration and still offer a better dropout voltage than conventional PNP − NPN based LDO regulators. In this mode the dropout is determined by the minimum control voltage. The CS5253B−1 is offered in a five−terminal D2PAK−5 package, which allows for the implementation of a remote−sense pin permitting very accurate regulation of output voltage directly at the load, where it counts, rather than at the regulator. This remote sensing feature virtually eliminates output voltage variations due to load changes and resistive voltage drops. Typical load regulation measured at the sense pin is less than 1.0 mV for an output voltage of 2.5 V with a load step of 10 mA to 3.0 A. The CS5253B−1 has a very fast transient loop response which can be adjusted using a small capacitor on the Adjust pin. Internal protection circuitry provides for “bust−proof” operation, similar to three−terminal regulators. This circuitry, which includes overcurrent, short circuit, and overtemperature protection will self protect the regulator under all fault conditions. The CS5253B−1 is ideal for generating a 2.5 V supply to power graphics controllers used on VGA cards. Its remote sense and low value capacitance requirements make this a low cost, high performance solution. The CS5253B−1 is optimized from the CS5253−1 to allow a lower value of output capacitor to be used at the expense of a slower transient response. Features http://onsemi.com 1 5 D2PAK−5 DP SUFFIX CASE 936AC Tab = VOUT Pin 1. VSENSE 2. Adjust 3. VOUT 4. VCONTROL 5. VPOWER MARKING DIAGRAM CS 5253B−1 AWLYWW 1 A WL Y WW = Assembly Location = Wafer Lot = Year = Work Week • • • • • • • • • • • • • Pb−Free Package is Available* VOUT Range is 1.25 V to 5.0 V @ 3.0 A VPOWER Dropout < 0.40 V @ 3.0 A VCONTROL Dropout < 1.05 V @ 3.0 A 1.0% Trimmed Reference Fast Transient Response Remote Voltage Sensing Thermal Shutdown Current Limit Short Circuit Protection Drop−In Replacement for EZ1582 Backwards Compatible with 3−Pin Regulators Very Low Dropout Reduces Total Power Consumption ORDERING INFORMATION Device CS5253B−1GDP5 CS5253B−1GDPR5 CS5253B−1GDPR5G Package D2PAK−5 Shipping† 50 Units/Rail D2PAK−5 750 Tape & Reel D2PAK−5 750 Tape & Reel (Pb−Free) †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. © Semiconductor Components Industries, LLC, 2004 1 June, 2004 − Rev. 5 Publication Order Number: CS5253B−1/D CS5253B−1 5.0 V VCONTROL VOUT RDIS 2.5 V @ 3.0 A 3.3 V CS5253B−1 VPOWER VSENSE 124 Adjust 100 mF 5.0 V 33 mF 5.0 V CLOAD (Optional) 10 mF 10 V GND 124 GND RDIS Figure 1. Application Diagram MAXIMUM RATINGS Rating VPOWER Input Voltage VCONTROL Input Voltage Operating Junction Temperature Range, TJ Storage Temperature Range ESD Damage Threshold Lead Temperature Soldering: Reflow: (SMD styles only) (Note 1) Value 6.0 13 0 to 150 −65 to +150 2.0 230 peak Unit V V °C °C kV °C Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. 1. 60 second maximum above 183°C. ELECTRICAL CHARACTERISTICS (0°C ≤ TA ≤ 70°C; 0°C ≤ TJ ≤ 150°C; VSENSE = VOUT and VADJ = 0 V; unless otherwise specified) Characteristic Reference Voltage Line Regulation Load Regulation Minimum Load Current (Note 2) Control Pin Current (Note 3) Adjust Pin Current Current Limit Short Circuit Current Ripple Rejection (Note 4) Thermal Regulation Test Conditions VCONTROL = 2.75 V to 12 V, VPOWER = 2.05 V to 5.5 V, IOUT = 10 mA to 3.0 A VCONTROL = 2.5 V to 12 V, VPOWER = 1.75 V to 5.5 V, IOUT = 10 mA VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 10 mA to 3.0 A, with Remote Sense VCONTROL = 5.0 V, VPOWER = 3.3 V, DVOUT = +1.0% VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 100 mA VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 3.0 A VCONTROL = 2.75 V, VPOWER = 2.05 V, IOUT = 10 mA VCONTROL = 2.75 V, VPOWER = 2.05 V, DVOUT = −4.0% VCONTROL = 2.75 V, VPOWER = 2.05 V, VOUT = 0 V VCONTROL = VPOWER = 3.25 V, VRIPPLE = 1.0 VP−P @ 120 Hz, IOUT = 3.0 A, CADJ = 0.1 mF 30 ms Pulse, TA = 25°C Min 1.237 (−1.0%) − − − − − − 3.1 2.0 60 − Typ 1.250 0.02 0.04 5.0 6.0 35 60 4.0 3.5 80 0.002 Max 1.263 (+1.0%) 0.2 0.3 10 10 120 120 − − − − Unit V % % mA mA mA mA A A dB %/W 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. The VCONTROL pin current is the drive current required for the output transistor. This current will track output current with roughly a 1:100 ratio. The minimum value is equal to the quiescent current of the device. 4. This parameter is guaranteed by design and is not 100% production tested. http://onsemi.com 2 CS5253B−1 ELECTRICAL CHARACTERISTICS (continued) (0°C ≤ TA ≤ 70°C; 0°C ≤ TJ ≤ 150°C; VSENSE = VOUT and VADJ = 0 V; unless otherwise specified.) Characteristic VCONTROL Dropout Voltage (Minimum VCONTROL − VOUT) (Note 5) VPOWER Dropout Voltage (Minimum VPOWER − VOUT) (Note 5) RMS Output Noise Temperature Stability Thermal Shutdown (Note 6) Thermal Shutdown Hysteresis VCONTROL Supply Only Output Current VPOWER Supply Only Output Current Test Conditions VPOWER = 2.05 V, IOUT = 100 mA VPOWER = 2.05 V, IOUT = 1.0 A VPOWER = 2.05 V, IOUT = 3.0 A VCONTROL = 2.75 V, IOUT = 100 mA VCONTROL = 2.75 V, IOUT = 1.0 A VCONTROL = 2.75 V, IOUT = 3.0 A Freq = 10 Hz to 10 kHz, TA = 25°C − − − VCONTROL = 13 V, VPOWER Not Connected, VADJ = VOUT = VSENSE = 0 V VPOWER = 6.0 V, VCONTROL Not Connected, VADJ = VOUT = VSENSE = 0 V Min − − − − − − − 0.5 150 − − − Typ 0.90 1.00 1.05 0.05 0.15 0.40 0.003 − 180 25 − 0.1 Max 1.15 1.15 1.30 0.15 0.25 0.60 − − 210 − 50 1.0 Unit V V V V V V %VOUT % °C °C mA mA 5. Dropout is defined as either the minimum control voltage (VCONTROL) or minimum power voltage (VPOWER) to output voltage differential required to maintain 1.0% regulation at a particular load current. 6. This parameter is guaranteed by design, but not parametrically tested in production. However, a 100% thermal shutdown functional test is performed on each part. PACKAGE PIN DESCRIPTION Package Pin # 1 2 Pin Symbol VSENSE Adjust Function This Kelvin sense pin allows for remote sensing of the output voltage at the load for improved regulation. It is internally connected to the positive input of the voltage sensing error amplifier. This pin is connected to the low side of the internally trimmed 1.0% bandgap reference voltage and carries a bias current of about 50 mA. A resistor divider from Adjust to VOUT and from Adjust to ground sets the output voltage. Also, transient response can be improved by adding a small bypass capacitor from this pin to ground. This pin is connected to the emitter of the power pass transistor and provides a regulated voltage capable of sourcing 3.0 A of current. This is the supply voltage for the regulator control circuitry. For the device to regulate, this voltage should be between 0.9 V and 1.3 V (depending on the output current) greater than the output voltage. The control pin current will be about 1.0% of the output current. This is the power input voltage. This pin is physically connected to the collector of the power pass transistor. For the device to regulate, this voltage should be between 0.1 V and 0.6 V greater than the output voltage depending on the output current. The output load current of 3.0 A is supplied through this pin. 3 4 VOUT VCONTRO L 5 VPOWER VPOWER VCONTROL BIAS and TSD VREF − + EA IA + − VOUT VSENSE Adjust Figure 2. Block Diagram http://onsemi.com 3 CS5253B−1 TYPICAL PERFORMANCE CHARACTERISTICS 1.253 1.252 Reference Voltage (V) 1.251 1.250 1.249 1.248 1.247 Load Regulation (%) 0.12 0.10 TJ = 120°C 0.08 0.06 0.04 TJ = 0°C 0.02 0 TJ = 20°C 0 20 40 60 80 100 120 0 0.5 1.0 1.5 2.0 2.5 3.0 Junction Temperature (°C) Output Current (A) Figure 3. Reference Voltage vs Junction Temperature Figure 4. Load Regulation vs Output Current 5.0 VOUT CS5253−1 COUT = 330 mF 4.5 4.0 Output Current (A) 3.5 3.0 2.5 2.0 1.5 1.0 Measured at DVOUT = −1.0% VCONTROL = 5.0 V VPOWER = 3.3 V VOUT = 2.5 V CCONTROL = 10 mF CADJ = 0.1 mF VOUT CS5253B−1 COUT = 33 mF 15 A/ms 80 A/ms ILOAD 10 mA to 3.0 A 0.5 0 0 1 2 3 4 5 6 VPOWER − VOUT (V) Figure 5. Transient Response Comparison between CS5253−1 and CS5253B−1 Figure 6. Output Current vs VPOWER − VOUT 85 Minimum Load Current (mA) 1200 1150 1100 1050 1000 950 900 850 VPOWER = 3.3 V DVOUT = +1.0% 80 IADJ (mA) 75 70 65 60 0 20 40 60 80 100 120 140 800 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 11 Junction Temperature (°C) VCONTROL − VOUT (V) Figure 7. Adjust Pin Current vs Junction Temperature Figure 8. Minimum Load Current vs VCONTROL − VOUT http://onsemi.com 4 CS5253B−1 3.9 Short Circuit Output Current Limit (A) 3.8 3.7 3.6 3.5 3.4 3.3 VCONTROL = 5.0 V VPOWER = 3.3 V Ripple Rejection (dB) 90 80 70 60 50 40 30 20 0 20 40 60 80 100 120 140 10 101 VIN − VOUT = 2.0 V IOUT = 3.0 A VRIPPLE = 1.0 VP−P COUT = 22 mF CADJ = 0.1 mF 102 103 104 105 106 Junction Temperature (°C) Frequency (Hz) Figure 9. Short Circuit Output Current vs Junction Temperature 12 10 8 IOUT (mA) 6 4 2 0 VCONTROL Dropout Voltage (mV) VCONTROL = 13 V VOUT = 0 V VPOWER Not Connected 1100 Figure 10. Ripple Rejection vs Frequency VPOWER = 2.05 V TJ = 0°C 1000 TJ = 20°C 900 TJ = 120°C 0 20 40 60 80 100 120 140 800 0 0.5 1.0 1.5 2.0 2.5 3.0 Junction Temperature (°C) Output Current (A) Figure 11. VCONTROL Only Output Current vs Junction Temperature Figure 12. VCONTROL Dropout Voltage vs Output Current 500 VPOWER Dropout Voltage (V) Minimum Load Current (mA) 450 400 350 300 250 200 150 50 0 0 0.5 1.0 1.5 2.0 2.5 3.0 TJ = 20°C TJ = 0°C TJ = 120°C 916.4 916.3 916.2 916.1 916.0 915.9 915.8 915.7 915.6 915.5 915.4 0.5 1.5 2.5 VPOWER − VOUT (V) 3.5 4.5 VCONTROL = 5.0 V DVOUT = +1.0% Output Current (A) Figure 13. VPOWER Dropout Voltage vs Output Current Figure 14. Minimum Load Current vs VPOWER − VOUT http://onsemi.com 5 CS5253B−1 30 25 20 IOUT (mA) 15 10 5 0 VPOWER = 6.0 V VOUT = 0 V VCONTROL Not Connected ICONTROL (mA) 40 35 30 25 20 15 10 5 0 20 40 60 80 100 120 140 0 0 20 40 60 80 IOUT = 100 mA 100 120 140 IOUT = 1.0 A VCONTROL = 2.75 V VPOWER = 2.05 V IOUT = 3.0 A Junction Temperature (°C) Junction Temperature (°C) Figure 15. VPOWER Only Output Current vs Junction Temperature 5.0 VPOWER = 3.3 V VCONTROL = 5.0 V VOUT set for 2.5 V TA = 25°C 4.5 ESR (W) Figure 16. VCONTROL Supply Current vs Junction Temperature 6 5 4 Unstable 3 2 Stable Region 1 VPOWER = 3.3 V VCONTROL = 5.0 V ILOAD = 0 to 3.0 A VOUT = 2.5 V VOUT Shorted to VSENSE TJ = 0°C to 150°C Current Limit (A) 4.0 3.5 0 0.5 1.0 1.5 VOUT (V) 2.0 2.5 3.0 0 0 10 20 30 40 50 60 70 80 90 100 Capacitance (mF) Figure 17. Current Limit vs VOUT Figure 18. Stability vs ESR APPLICATIONS NOTES THEORY OF OPERATION The CS5253B−1 linear regulator provides adjustable voltages from 1.25 V to 5.0 V at currents up to 3.0 A. The regulator is protected against short circuits, and includes a thermal shutdown circuit with hysteresis. The output, which is current limited, consists of a PNP−NPN transistor pair and requires an output capacitor for stability. A detailed procedure for selecting this capacitor is included in the Stability Considerations section. VPOWER Function limited to about three milliamperes until the power input voltage comes up. If the power input voltage comes up first, the output will not turn on at all until the control voltage comes up. The output can never come up unregulated. The CS5253B−1 can also be used as a single supply device with the control and power inputs tied together. In this mode, the dropout will be determined by the minimum control voltage. Output Voltage Sensing The CS5253B−1 utilizes a two supply approach to maximize efficiency. The collector of the power device is brought out to the VPOWER pin to minimize internal power dissipation under high current loads. VCONTROL provides for the control circuitry and the drive for the output NPN transistor. VCONTROL should be at least 1.0 V greater than the output voltage. Special care has been taken to ensure that there are no supply sequencing problems. The output voltage will not turn on until both supplies are operating. If the control voltage comes up first, the output current will be The CS5253B−1 five terminal linear regulator includes a dedicated VSENSE function. This allows for true Kelvin sensing of the output voltage. This feature can virtually eliminate errors in the output voltage due to load regulation. Regulation will be optimized at the point where the sense pin is tied to the output. http://onsemi.com 6 CS5253B−1 DESIGN GUIDELINES Remote Sense Remote sense operation can be easily obtained with the CS5253B−1 but some care must be paid to the layout and positioning of the filter capacitors around the part. The ground side of the input capacitors on the +5.0 V and +3.3 V lines and the local VOUT−to−ground local output capacitor on the IC output must be tied close to the ground connected resistor voltage divider feedback network. The top resistor of the divider must be connected directly to the VSENSE pin of the regulator. This will establish the stability of the part. This capacitor−divider resistor connection may then be connected to ground remotely at the load, giving the ground portion remote sense operation. The VSENSE line can then be tied remotely at the load connection, giving the feedback remote sense operation. The remote sense lines should be Kelvin connected so as to eliminate the effect of load current voltage drop. An optional bypass capacitor may be used at the load to reduce the effect of load variations and spikes. RDIS +5.0 V +3.3 V + + VCONTROL VPOWER VOUT VSENSE 124 ADJ + +Load CS5253B−1 10 mF 100 mF Local Connections 33 mF Remote Connections + Optional 124 GND RDIS −Load Figure 19. Remote Sense Adjustable Operation This LDO adjustable regulator has an output voltage range of 1.25 V to 5.0 V. An external resistor divider sets the output voltage as shown in Figure 20. The regulator’s voltage sensing error amplifier maintains a fixed 1.25 V reference between the output pin and the adjust pin. 5.0 V VCONTROL CS5253B−1 3.3 V VPOWER Adjust VSENSE R1 VOUT 2.5 V @ 3.0 A should be taken into account if precise adjustment of VOUT is necessary. The output voltage is set according to the formula: VOUT + 1.25 V R1 ) R2 ) R2 R1 IADJ 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 overtemperature. While not required, a bypass capacitor connected between the adjust pin and ground will improve transient response and ripple rejection. A 0.1 mF tantalum capacitor is recommended for “first cut” design. Value and type may be varied to optimize performance vs. price. Other Adjustable Operation Considerations R2 Figure 20. Typical Application Schematic. The Resistor Divider Sets VOUT, With the Internal 1.260 V Reference Dropped Across R1. 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 mA) also flows through R2 and adds a small error that The CS5253B−1 linear regulator has an absolute maximum specification of 6.0 V for the voltage difference between VPOWER and VOUT. However, the IC may be used to regulate voltages in excess of 6.0 V. The two main considerations in such a design are the sequencing of power supplies and short circuit capability. Power supply sequencing should be such that the VCONTROL supply is brought up coincidentally with or before the VPOWER supply. This allows the IC to begin charging the output capacitor as soon as the VPOWER to VOUT differential is large enough that the pass transistor conducts. As VPOWER increases, the pass transistor will remain in dropout, and current is passed to the load until http://onsemi.com 7 CS5253B−1 VOUT is in regulation. Further increase in the supply voltage brings the pass transistor out of dropout. In this manner, any output voltage less than 13 V may be regulated, provided the VPOWER to VOUT differential is less than 6.0 V. In the case where VCONTROL and VPOWER are shorted, there is no theoretical limit to the regulated voltage as long as the VPOWER to VOUT differential of 6.0 V is not exceeded. There is a possibility of damaging the IC when VPOWER − VOUT is greater than 6.0 V if a short circuit occurs. Short circuit conditions will result in the immediate operation of the pass transistor outside of its safe operating area. Overvoltage 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 the VPOWER to VOUT differential to less than 6.0 V if fail safe operation is required. One possible clamp circuit is illustrated in Figure 21; 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 condition indefinitely while protecting the IC. External Supply capacitors being less expensive in general, but varying more in capacitor value and ESR overtemperature. The CS5253B−1 requires an output capacitor to guarantee loop stability. The Stability vs ESR graph in the typical performance section shows the minimum ESR needed to guarantee stability, but under ideal conditions. These include: having VOUT connected to VSENSE directly at the IC pins; the compensation capacitor located right at the pins with a minimum lead length; the adjust feedback resistor divider ground, (bottom of R2 in Figure 20), connected right at the capacitor ground; and with power supply decoupling capacitors located close to the IC pins. The actual performance will vary greatly with board layout for each application. In particular, the use of the remote sensing feature will require a larger capacitor with less ESR. For most applications, a minimum of 33 mF tantalum or 150 mF aluminum electrolytic, with an ESR less than 1.0 W overtemperature, is recommended. Larger capacitors and lower ESR will improve stability. The load transient response, during the time it takes the regulator to respond, is also determined by the output capacitor. For large changes in load current, the ESR of the output capacitor causes an immediate drop in output voltage given by: DV + DI ESR External Supply VCONTROL VSENSE CS5253B−1 VPOWER VOUT VADJ There is then an additional drop in output voltage given by: DV + DI TC Figure 21. This Circuit Is an Example of How the CS5253B−1 Can Be Short−Circuit Protected When Operating With VOUT > 6.0 V Stability Considerations where T is the time for the regulation loop to begin to respond. The very fast transient response time of the CS5253B−1 allows the ESR effect to dominate. 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 transient response. Protection Diodes The output compensation capacitor helps determine three main characteristics of a linear regulator: loop stability, startup delay, and load transient response. Different capacitor types vary widely in tolerance, Equivalent Series Resistance (ESR), Equivalent Series Inductance (ESI), and variation overtemperature. Tantalum and aluminum electrolytic capacitors work best, with electrolytic 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 VCONTROL drops. In the CS5253B−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 http://onsemi.com 8 CS5253B−1 capacitance and the input voltage is instantaneously shorted to ground, damage can occur. In this case, a diode connected as shown in Figure 22 is recommended. Calculating Power Dissipation and Heatsink Requirements VCONTROL CS5253B−1 VPOWER Adjust VOUT VSENSE High power regulators such as the CS5253B−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 heatsink is used. Since the package tab is connected to VOUT on the CS5253B−1, electrical isolation may be required for some applications. Also, as with all high power packages, thermal compound in 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: TJ(max) + TA(max) ) PD(max) RqJA Figure 22. Diode Protection Circuit A rule of thumb useful in determining if a protection diode is required is to solve for current: I+C V T 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) * VOUT(min))IOUT(max) ) VIN(max) IIN(max) where: I is the current flow out of the load capacitance when VCONTROL is shorted, C is the value of load capacitance V is the output voltage, and T is the time duration required for VCONTROL to transition from high to being shorted. 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 the use of a protection diode. Current Limit The internal current limit circuit limits the output current under excessive load conditions. Short Circuit Protection A heatsink 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 which is measured in degrees per watt. Like series electrical resistances, these thermal resistances are summed to determine the total thermal resistance between the die junction and the surrounding air, RqJA. This total thermal resistance is comprised of three components. These resistive terms are measured from junction−to−case (RqJC), case−to−heatsink (RqCS), and heatsink−to−ambient air (RqSA). The equation is: The value for RQJC is 2.5°C/watt for the CS5253B−1 in the D2PAK−5 package. For a high current regulator such as the CS5253B−1 the majority of heat is generated in the power transistor section. The value for RqSA depends on the heatsink type, while the RqCS depends on factors such as package type, heatsink interface (is an insulator and thermal grease used?), and the contact area between the heatsink and the package. Once these calculations are complete, the maximum permissible value of RqJA can be calculated and the proper heatsink selected. For further discussion on heatsink selection, see our application note “Thermal Management,” document number AND8036/D. RqJA + RqJC ) RqCS ) RqSA The device includes short circuit protection circuitry that clamps the output current at approximately 500 mA less than its current limit value. This provides for a current foldback function, which reduces power dissipation under a direct shorted load. Thermal Shutdown The thermal shutdown circuitry is guaranteed by design to activate above a die junction temperature of approximately 150°C and to shut down the regulator output. This circuitry has 25°C of typical hysteresis, thereby allowing the regulator to recover from a thermal fault automatically. http://onsemi.com 9 CS5253B−1 PACKAGE DIMENSIONS D2PAK−5 DP SUFFIX CASE 936AC−01 ISSUE O For D2PAK Outline and Dimensions − Contact Factory PACKAGE THERMAL DATA Parameter RqJC RqJA Typical Typical D2PAK−5 2.5 10−50* Unit °C/W °C/W *Depending on thermal properties of substrate. RqJA = RqJC + RqCA. ON Semiconductor and are registered 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. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. 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