Order this document by MC78T00/D This family of fixed voltage regulators are monolithic integrated circuits capable of driving loads in excess of 3.0 A. These three–terminal regulators employ internal current limiting, thermal shutdown, and safe–area compensation. Devices are available with improved specifications, including a 2% output voltage tolerance, on AC–suffix 5.0, 12 and 15 V device types. Although designed primarily as a fixed voltage regulator, these devices can be used with external components to obtain adjustable voltages and currents. This series of devices can be used with a series–pass transistor to supply up to 15 A at the nominal output voltage. • Output Current in Excess of 3.0 A • • • • • • • THREE–AMPERE POSITIVE FIXED VOLTAGE REGULATORS SEMICONDUCTOR TECHNICAL DATA Power Dissipation: 25 W No External Components Required Output Voltage Offered in 2% and 4% Tolerance* T SUFFIX PLASTIC PACKAGE CASE 221A Thermal Regulation is Specified Internal Thermal Overload Protection Internal Short Circuit Current Limiting Output Transistor Safe–Area Compensation MAXIMUM RATINGS (TA = +25°C, unless otherwise noted.) Rating Input Voltage (5.0 V – 12 V) Input Voltage (15 V) Power Dissipation and Thermal Characteristics Plastic Package (Note 1) TA = +25°C Thermal Resistance, Junction–to–Air TC = +25°C Thermal Resistance, Junction–to–Case Storage Junction Temperature Operating Junction Temperature Range (MC78T00C, AC) Symbol Value Unit VI 35 40 Vdc PD RθJA PD RθJC Pin 1. Input 2. Ground 3. Output 1 2 3 Heatsink surface is connected to Pin 2. Internally Limited 65 °C/W Internally Limited 2.5 °C/W Tstg +150 °C TJ 0 to +125 °C NOTES: 1. Although power dissipation is internally limited, specifications apply only for PO ≤ Pmax, Pmax = 25 W. DEVICE TYPE/NOMINAL OUTPUT VOLTAGE MC78T05 MC78T08 5.0 V 8.0 V MC78T12 MC78T15 12 V 15 V ORDERING INFORMATION Simplified Application VO Tol. Operating Temperature Range Package MC78TXXCT MC78TXXACT 4% 2%* TJ = 0° to +125°C Plastic Power MC78TXXBT# MC78TXXABT# 4% 2%* TJ = – 40° to +125°C Plastic Power Device Input Cin* 0.33µF MC78TXX Output CO** A common ground is required between the input and the output voltages. The input voltage must remain typically 2.2 V above the output voltage even during the low point on the input ripple voltage. XX Indicates nominal voltage. XX these two digits of the type number indicate voltage. # Automotive temperature range selections are available with special test conditions and additional tests. Contact your local Motorola sales office for information. ** Cin is required if regulator is located an appreciable distance from power supply filter. ** (See Applications Information for details.) ** CO is not needed for stability; however, it does improve transient response. * 2% regulators available in 5, 12 and 15 V devices. Motorola, Inc. 1996 MOTOROLA ANALOG IC DEVICE DATA Rev 1 1 MC78T00 Series ELECTRICAL CHARACTERISTICS (Vin = 10 V, IO = 3.0 A, 0°C ≤ TJ ≤ 125°C, PO ≤ Pmax [Note 1], unless otherwise noted.) MC78T05AC Characteristics Output Voltage (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A; 5.0 mA ≤ IO ≤ 2.0 A, 7.3 Vdc ≤ Vin ≤ 20 Vdc) Symbol Regline Load Regulation (Note 2) (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Regload Quiescent Current (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Typ Max Min Typ Max 4.9 4.8 5.0 5.0 5.1 5.2 4.8 4.75 5.0 5.0 5.2 5.25 – 3.0 25 – 3.0 25 – – 10 15 30 80 – – 10 15 30 80 – 0.001 0.01 – 0.002 0.03 – – 3.5 4.0 5.0 6.0 – – 3.5 4.0 5.0 6.0 VO Line Regulation (Note 2) (7.2 Vdc ≤ Vin ≤ 35 Vdc, IO = 5.0 mA, TJ = +25°C; 7.2 Vdc ≤ Vin ≤ 35 Vdc, IO = 1.0 A, TJ = +25°C; 8.0 Vdc ≤ Vin ≤ 12 Vdc, IO = 3.0 A, TJ = +25°C; 7.5 Vdc ≤ Vin ≤ 20 Vdc, IO = 1.0 A) Thermal Regulation (Pulse = 10 ms, P = 20 W, TA = +25°C) MC78T05C Min Regtherm Unit Vdc mV mV IB %VO/W mA Quiescent Current Change (7.2 Vdc ≤ Vin ≤ 35 Vdc, IO = 5.0 mA, TJ = +25°C; 5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C; 7.5 Vdc ≤ Vin ≤ 20 Vdc, IO = 1.0 A) ∆IB – 0.3 1.0 – 0.3 1.0 mA Ripple Rejection (8.0 Vdc ≤ Vin ≤ 18 Vdc, f = 120 Hz, IO = 2.0 A, TJ = 25°C) RR 62 75 – 62 75 – dB Dropout Voltage (IO = 3.0 A, TJ = +25°C) Vin–VO – 2.2 2.5 – 2.2 2.5 Vdc Output Noise Voltage (10 Hz ≤ f ≤ 100 kHz, TJ = +25°C) Vn – 10 – – 10 – µV/VO Output Resistance (f = 1.0 kHz) RO – 2.0 – – 20 – mΩ Short Circuit Current Limit (Vin = 35 Vdc, TJ = +25°C) ISC – 1.5 – – 1.5 – A Peak Output Current (TJ = +25°C) Imax – 5.0 – – 5.0 – A TCVO – 0.2 – – 0.2 – mV/°C Average Temperature Coefficient of Output Voltage (IO = 5.0 mA) NOTES: 1. Although power dissipation is internally limited, specifications apply only for PO ≤ Pmax, Pmax = 25 W. 2. Line and load regulation are specified at constant junction temperature. Changes in VO due to heating effects must be taken into account separately. Pulse testing with low duty cycle is used. 2 MOTOROLA ANALOG IC DEVICE DATA MC78T00 Series ELECTRICAL CHARACTERISTICS (Vin = 13 V, IO = 3.0 A, 0°C ≤ TJ ≤ 125°C, PO ≤ Pmax [Note 1], unless otherwise noted.) MC78T08C Characteristics Output Voltage (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A; 5.0 mA ≤ IO ≤ 2.0 A, 10.4 Vdc ≤ Vin ≤ 23 Vdc) Symbol Regline Load Regulation (Note 2) (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Regload Quiescent Current (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Typ Max 7.7 7.6 8.0 8.0 8.3 8.4 – 4.0 35 – – 10 15 30 80 – 0.002 0.03 – – 3.5 4.0 5.0 6.0 VO Line Regulation (Note 2) (10.3 Vdc ≤ Vin ≤ 35 Vdc, IO = 5.0 mA, TJ = +25°C 10.3 Vdc ≤ Vin ≤ 35 Vdc, IO = 1.0 A, TJ = +25°C 11 Vdc ≤ Vin ≤ 17 Vdc, IO = 3.0 A, TJ = +25°C 10.7 Vdc ≤ Vin ≤ 23 Vdc, IO = 1.0 A) Thermal Regulation (Pulse = 10 ms, P = 20 W, TA = +25°C) Min Regtherm Unit Vdc mV mV IB %VO/W mA Quiescent Current Change (10.3 Vdc ≤ Vin ≤ 35 Vdc, IO = 5.0 mA, TJ = +25°C; 5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C; 10.7 Vdc ≤ Vin ≤ 23 Vdc, IO = 1.0 A) ∆IB – 0.3 1.0 mA Ripple Rejection (11 Vdc ≤ Vin ≤ 21 Vdc, f = 120 Hz, IO = 2.0 A, TJ = 25°C) RR 60 71 – dB Vin–VO – 2.2 2.5 Vdc Output Noise Voltage (10 Hz ≤ f ≤ 100 kHz, TJ = +25°C) Vn – 10 – µV/VO Output Resistance (f = 1.0 kHz) RO – 2.0 – mΩ Short Circuit Current Limit (Vin = 35 Vdc, TJ = +25°C) ISC – 1.5 – A Peak Output Current (TJ = +25°C) Imax – 5.0 – A TCVO – 0.3 – mV/°C Dropout Voltage (IO = 3.0 A, TJ = +25°C) Average Temperature Coefficient of Output Voltage (IO = 5.0 mA) NOTES: 1. Although power dissipation is internally limited, specifications apply only for PO ≤ Pmax, Pmax = 25 W. 2. Line and load regulation are specified at constant junction temperature. Changes in VO due to heating effects must be taken into account separately. Pulse testing with low duty cycle is used. MOTOROLA ANALOG IC DEVICE DATA 3 MC78T00 Series ELECTRICAL CHARACTERISTICS (Vin = 17 V, IO = 3.0 A, 0°C ≤ TJ ≤ 125°C, PO ≤ Pmax [Note 1], unless otherwise noted.) MC78T12AC Characteristics Output Voltage (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A, 5.0 mA ≤ IO ≤ 2.0 A, 14.5 Vdc ≤ Vin ≤ 27 Vdc) Symbol Regline Load Regulation (Note 2) (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Regload Quiescent Current (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Typ Max Min Typ Max 11.75 11.5 12 12 12.25 12.5 11.5 11.4 12 12 12.5 12.6 – 6.0 45 – 6.0 45 – – 10 15 30 80 – – 10 15 30 80 – 0.001 0.01 – 0.002 0.03 – – 3.5 4.0 5.0 6.0 – – 3.5 4.0 5.0 6.0 VO Line Regulation (Note 2) (14.5 Vdc ≤ Vin ≤ 35 Vdc, IO = 5.0 mA, TJ = +25°C; 14.5 Vdc ≤ Vin ≤ 35 Vdc, IO = 1.0 A, TJ = +25°C; 16 Vdc ≤ Vin ≤ 22 Vdc, IO = 3.0 A, TJ = +25°C; 14.9 Vdc ≤ Vin ≤ 27 Vdc, IO = 1.0 A) Thermal Regulation (Pulse = 10 ms, P = 20 W, TA = +25°C) MC78T12C Min Regtherm Unit Vdc mV mV IB %VO/W mA Quiescent Current Change (14.5 Vdc ≤ Vin ≤ 35 Vdc, IO = 5.0 mA, TJ = +25°C; 5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C; 14.9 Vdc ≤ Vin ≤ 27 Vdc, IO = 1.0 A) ∆IB – 0.3 1.0 – 0.3 1.0 mA Ripple Rejection (15 Vdc ≤ Vin ≤ 25 Vdc, f = 120 Hz, IO = 2.0 A, TJ = 25°C) RR 57 67 – 57 67 – dB Dropout Voltage (IO = 3.0 A, TJ = +25°C) Vin – VO – 2.2 2.5 – 2.2 2.5 Vdc Output Noise Voltage (10 Hz ≤ f ≤ 100 kHz, TJ = +25°C) Vn – 10 – – 10 – µV/VO Output Resistance (f = 1.0 kHz) RO – 2.0 – – 20 – mΩ Short Circuit Current Limit (Vin = 35 Vdc, TJ = +25°C) ISC – 1.5 – – 1.5 – A Peak Output Current (TJ = +25°C) Imax – 5.0 – – 5.0 – A Average Temperature Coefficient of Output Voltage (IO = 5.0 mA) TCVO – 0.5 – – 0.5 – mV/°C NOTES: 1. Although power dissipation is internally limited, specifications apply only for PO ≤ Pmax, Pmax = 25 W. 2. Line and load regulation are specified at constant junction temperature. Changes in VO due to heating effects must be taken into account separately. Pulse testing with low duty cycle is used. 4 MOTOROLA ANALOG IC DEVICE DATA MC78T00 Series ELECTRICAL CHARACTERISTICS (Vin = 20 V, IO = 3.0 A, 0°C ≤ TJ ≤ 125°C, PO ≤ Pmax [Note 1], unless otherwise noted.) MC78T15AC Characteristics Output Voltage (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A; 5.0 mA ≤ IO ≤ 2.0 A, 17.5 Vdc ≤ Vin ≤ 30 Vdc) Symbol Regline Load Regulation (Note 2) (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Regload Quiescent Current (5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C) (5.0 mA ≤ IO ≤ 3.0 A) Typ Max Min Typ Max 14.7 14.4 15 15 15.3 15.6 14.4 14.25 15 15 15.6 15.75 – 7.5 55 – 7.5 55 – – 10 15 30 80 – – 10 15 30 80 – 0.001 0.01 – 0.002 0.03 – – 3.5 4.0 5.0 6.0 – – 3.5 4.0 5.0 6.0 VO Line Regulation (Note 2) (17.6 Vdc ≤ Vin ≤ 40 Vdc, IO = 5.0 mA, TJ = +25°C; 17.6 Vdc ≤ Vin ≤ 40 Vdc, IO = 1.0 A, TJ = +25°C; 20 Vdc ≤ Vin ≤ 26 Vdc, IO = 3.0 A, TJ = +25°C; 18 Vdc ≤ Vin ≤ 30 Vdc, IO = 1.0 A) Thermal Regulation (Pulse = 10 ms, P = 20 W, TA = +25°C) MC78T15C Min Regtherm Unit Vdc mV mV IB %VO/W mA Quiescent Current Change (17.6 Vdc ≤ Vin ≤ 40 Vdc, IO = 5.0 mA, TJ = +25°C; 5.0 mA ≤ IO ≤ 3.0 A, TJ = +25°C; 18 Vdc ≤ Vin ≤ 30 Vdc, IO = 1.0 A) ∆IB – 0.3 1.0 – 0.3 1.0 mA Ripple Rejection (18.5 Vdc ≤ Vin ≤ 28.5 Vdc, f = 120 Hz, IO = 2.0 A, TJ = 25°C) RR 55 65 – 55 65 – dB Dropout Voltage (IO = 3.0 A, TJ = +25°C) Vin–VO – 2.2 2.5 – 2.2 2.5 Vdc Output Noise Voltage (10 Hz ≤ f ≤ 100 kHz, TJ = +25°C) Vn – 10 – – 10 – µV/VO Output Resistance (f = 1.0 kHz) RO – 2.0 – – 20 – mΩ Short Circuit Current Limit (Vin = 40 Vdc, TJ = +25°C) ISC – 1.0 – – 1.0 – A Peak Output Current (TJ = +25°C) Imax – 5.0 – – 5.0 – A TCVO – 0.6 – – 0.6 – mV/°C Average Temperature Coefficient of Output Voltage (IO = 5.0 mA) NOTES: 1. Although power dissipation is internally limited, specifications apply only for PO ≤ Pmax, Pmax = 25 W. 2. Line and load regulation are specified at constant junction temperature. Changes in VO due to heating effects must be taken into account separately. Pulse testing with low duty cycle is used. MOTOROLA ANALOG IC DEVICE DATA 5 MC78T00 Series VOLTAGE REGULATOR PERFORMANCE Figure 1. MC78T05AC Line and Thermal Regulation Figure 2. MC78T05AC Load and Thermal Regulation 2 2 1 (2.0 mV/DIV) 18 8.0 2 1 2 2.0 0 t, TIME (2.0 ms/DIV) t, TIME (2.0 ms/DIV) Vout = 5.0 V Vin = 8.0 V → 18 V → 8.0 V Iout = 2.0 A (2.0 mV/DIV) I O , OUTPUT ∆ V O , OUTPUT CURRENT (A) VOLTAGE DEVIATION (V) can be caused by a change in either the input voltage or the load current. Thermal regulation is a function of IC layout and die attach techniques, and usually occurs within 10 ms of a change in power dissipation. After 10 ms, additional changes in the output voltage are due to the temperature coefficient of the device. Figure 1 shows the line and thermal regulation response of a typical MC78T05AC to a 20 W input pulse. The variation of the output voltage due to line regulation is labeled ➀ and the thermal regulation component is labeled ➁. Figure 2 shows the load and thermal regulation response of a typical MC78T05AC to a 20 W load pulse. The output voltage variation due to load regulation is labeled ➀ and the thermal regulation component is labeled ➁. ∆ V O , OUTPUT V in , INPUT VOLTAGE DEVIATION (V) VOLTAGE (V) The performance of a voltage regulator is specified by its immunity to changes in load, input voltage, power dissipation, and temperature. Line and load regulation are tested with a pulse of short duration (< 100µs) and are strictly a function of electrical gain. However, pulse widths of longer duration (> 1.0 ms) are sufficient to affect temperature gradients across the die. These temperature gradients can cause a change in the output voltage, in addition to changes caused by line and load regulation. Longer pulse widths and thermal gradients make it desirable to specify thermal regulation. Thermal regulation is defined as the change in output voltage caused by a change in dissipated power for a specified time, and is expressed as a percentage output voltage change per watt. The change in dissipated power Vout = 5.0 V Vin = 15 Iout = 0 A → 2.0 A → 0 A 1 = Regline = 2.4 mV 2 = Regtherm = 0.0015%VO/W 1 = Regline = 4.4 mV 2 = Regtherm = 0.0015%VO/W Representative Schematic Diagram Q1 1.0k Input 1.0k Q2 Q20 Q22 6.7V 210 Q21 16k Q24 Q9 Q3 Q4 3.0k 3.6k Q19 5.6k 6.4k Q5 Q6 Q11 Q13 Q7 6.0k 6 Q27 13 200 0.12 Output 40 pF Q12 2.0k Q26 300 50 520 2.6k 8.0–15 VO 5.0 VO 3.9k 10pF Q23 Q16 Q10 Q25 200 1.0k Q8 300 100 6.0k Q17 Q18 Q15 Q14 2.8k Gnd MOTOROLA ANALOG IC DEVICE DATA MC78T00 Series Figure 3. Temperature Stability Figure 4. Output Impedance 100 r O , OUTPUT IMPEDANCE ( Ω ) NORMALIZED OUTPUT VOLTAGE 1.02 Vin – Vout = 10 V Iout = 100 mA 1.0 .98 –90 –50 –10 30 70 110 TJ, JUNCTION TEMPERATURE (°C) 150 10–1 10–2 10–3 10–4 1.0 190 RR, RIPPLE REJECTION (dB) Iout = 50 mA 80 Iout = 1.5 A 60 Vout = 5.0 V Vin = 10 V CO = 0 TJ = 25°C 40 20 1.0 4.0 10 100 1.0 k 10 k 100 k 1.0 M 10 M 1.0 k 10 k 100 k f, FREQUENCY (Hz) 1.0 M 10 M 100 M Vout = 5.0 V Vin = 10 V CO = 0 f = 120 Hz TJ = 25°C 40 0.1 1.0 10 Iout, OUTPUT CURRENT (A) Figure 7. Quiescent Current versus Input Voltage Figure 8. Quiescent Current versus Output Current 5.0 TJ = 25°C 3.0 TJ = 125°C 2.0 TJ = 0°C TJ = 25°C TJ = 125°C 0 60 f, FREQUENCY (Hz) TJ = 0°C 1.0 80 30 0.01 100 M IB , QUIESCENT CURRENT (mA) RR, RIPPLE REJECTION (dB) 100 100 100 IB , QUIESCENT CURRENT (mA) 10 Figure 6. Ripple Rejection versus Output Current Figure 5. Ripple Rejection versus Frequency 0 Vout = 5.0 V Vin = 7.5 V Iout = 1.0 A CO = 0 TJ = 25°C 10 20 Vin, INPUT VOLTAGE (Vdc) MOTOROLA ANALOG IC DEVICE DATA 30 40 TJ = 0°C 4.0 TJ = 25°C 3.0 TJ = 125°C 2.0 1.0 0 0.01 Vin–Vout = 5.0 V 0.1 1.0 10 Iout, OUTPUT CURRENT (A) 7 MC78T00 Series Figure 9. Dropout Voltage Figure 10. Peak Output Current 8.0 I max, PEAK OUTPUT CURRENT (A) V in –Vout , INPUT TO OUTPUT VOLTAGE DIFFERENTIAL (Vdc) 2.5 Iout = 3.0 A 2.0 Iout = 1.0 A 1.5 Iout = 0.5 A 1.0 ∆VO = 50 mV 0.5 –90 6.0 4.0 2.0 TJ = 0°C TJ = 25°C TJ = 125°C 0 –50 –10 30 70 110 150 190 0 10 TJ, JUNCTION TEMPERATURE (°C) 8 I out , OUTPUT ∆ V out , OUTPUT VOLTAGE DEVIATION (V) CURRENT (A) 0.4 0.2 0 –0.2 –0.4 –0.6 1.0 0.5 0 0 10 20 30 40 Figure 12. Load Transient Response Vout = 5.0 V Iout = 150 mA CO = 0 TJ = 25°C 30 0.3 Vin = 10 V CO = 0 TJ = 25°C 0.2 0.1 0 –0.1 –0.2 –0.3 1.5 1.0 0.5 0 0 40 10 20 30 40 t, TIME (µs) t, TIME (µs) P D(AV) , MAXIMUM AVERAGE POWER DISSIPATION (W) ∆ Vin , INPUT VOLTAGE CHANGE (V) ∆ V out , OUTPUT VOLTAGE DEVIATION (V) Figure 11. Line Transient Response 0.8 0.6 20 Vin–VO, INPUT–OUTPUT VOLTAGE (Vdc) Figure 13. Maximum Average Power Dissipation for MC78T00CT, ACT 40 30 Maximum Ambient Temperature θSA of Heatsinks 1.3°C/W 2.4°C/W Infinite Heatsink 20 3.3°C/W 10 6.3°C/W 10.5°C 0 25 50 75 100 125 TA, AMBIENT TEMPERATURE (°C) MOTOROLA ANALOG IC DEVICE DATA MC78T00 Series APPLICATIONS INFORMATION Design Considerations The MC78T00 Series of fixed voltage regulators are designed with Thermal Overload Protection that shuts down the circuit when subjected to an excessive power overload condition, Internal Short Circuit Protection that limits the maximum current the circuit will pass, and Output Transistor Safe–Area Compensation that reduces the output short circuit current as the voltage across the pass transistor is increased. In many low current applications, compensation capacitors are not required. However, it is recommended that the regulator input be bypassed with a capacitor if the regulator is connected to the power supply filter with long wire lengths, or if the output load capacitance is large. An input bypass capacitor should be selected to provide good high frequency characteristics to insure stable operation under all load conditions. A 0.33 µF or larger tantalum, mylar, or other capacitor having low internal impedance at high frequencies should be chosen. The bypass capacitor should be mounted with the shortest possible leads directly across the regulator’s input terminals. Normally good construction techniques should be used to minimize ground loops and lead resistance drops since the regulator has no external sense lead. Figure 14. Current Regulator Figure 15. Adjustable Output Regulator MC78T05 Input Output R 0.33µF MC78T05 Constant Current to Grounded Load Input IO The MC78T05 regulator can also be used as a current source when connected as above. In order to minimize dissipation the MC78T05 is chosen in this application. Resistor R determines the current as follows: 5.0 V IO = R + IB ^ ^ ∆IB 0.7 mA over line, load and Temperature changes IB 3.5 mA For example, a 2.0 A current source would require R to be a 2.5 Ω, 10 W resistor and the output voltage compliance would be the input voltage less 7.0 V. 7 0.1µF + 3 10k 4 MC1741 VO, 8.0 V to 20 V Vin – VO ≥ 2.5 V The addition of an operational amplifier allows adjustment to higher or intermediate values while retaining regulation characteristics. The minimum voltage obtainable with this arrangement is 3.0 V greater than the regulator voltage. Figure 17. Current Boost With Short Circuit Protection 2N4398 or Equiv Input MC78TXX 2 6 1.0k Figure 16. Current Boost Regulator R – 0.33µF Rsc Output 2N4398 or Equiv. MJ2955 or Equiv. R MC78TXX 1.0µF 0.1µF Output 1.0µF XX = 2 digits of type number indicating voltage. The MC78T00 series can be current boosted with a PNP transistor. The 2N4398 provides current to 15 A. Resistor R in conjuction with the VBE of the PNP determines when the pass transistor begins conducting; this circuit is not short circuit proof. Input–output differential voltage minimum is increased by the VBE of the pass transistor. MOTOROLA ANALOG IC DEVICE DATA XX = 2 digits of type number indicating voltage. The circuit of Figure 17 can be modified to provide supply protection against short circuits by adding a short circuit sense resistor, RSC, and an additional PNP transistor. The current sensing PNP must be able to handle the short circuit current of the three–terminal regulator. Therefore, an eight–ampere power transistor is specified. 9 MC78T00 Series OUTLINE DIMENSIONS T SUFFIX PLASTIC PACKAGE CASE 221A–06 ISSUE Y –T– B C F T S 4 A Q 1 2 3 U H K Z L R V J G D N 10 SEATING PLANE 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. DIM A B C D F G H J K L N Q R S T U V Z 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 MOTOROLA ANALOG IC DEVICE DATA MC78T00 Series Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola 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 consequential or incidental damages. “Typical” parameters which may be provided in Motorola 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. Motorola does not convey any license under its patent rights nor the rights of others. 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MOTOROLA ANALOG IC DEVICE DATA 11 MC78T00 Series How to reach us: USA / EUROPE / Locations Not Listed: Motorola Literature Distribution; P.O. Box 20912; Phoenix, Arizona 85036. 1–800–441–2447 or 602–303–5454 JAPAN: Nippon Motorola Ltd.; Tatsumi–SPD–JLDC, 6F Seibu–Butsuryu–Center, 3–14–2 Tatsumi Koto–Ku, Tokyo 135, Japan. 03–81–3521–8315 MFAX: [email protected] – TOUCHTONE 602–244–6609 INTERNET: http://Design–NET.com ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park, 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852–26629298 12 ◊ *MC78T00/D* MOTOROLA ANALOG IC DEVICE DATA MC78T00/D