Document
LM2984C Microprocessor Power Supply System
May 1989
LM2984C Microprocessor Power Supply System
General Description
The LM2984C positive voltage regulator features three independent and tracking outputs capable of delivering the power for logic circuits peripheral sensors and standby memory in a typical microprocessor system The LM2984C includes circuitry which monitors both its own high-current output and also an external mP If any error conditions are sensed in either a reset error flag is set and maintained until the malfunction terminates Since these functions are included in the same package with the three regulators a great saving in board space can be realized in the typical microprocessor system The LM2984C also features very low dropout voltages on each of its three regulator outputs (0 6V at the rated output current) Furthermore the quiescent current can be reduced to 1 mA in the standby mode Designed also for vehicular applications the LM2984C and all regulated circuitry are protected from reverse battery installations or 2-battery jumps Familiar regulator features such as short circuit and thermal overload protection are also provided Fixed outputs of 5V are available in the plastic TO-220 power package
Features
Y Y Y Y Y Y Y Y Y Y Y Y Y
Three low dropout tracking regulators Output current in excess of 500 mA Low quiescent current standby regulator Microprocessor malfunction RESET flag Delayed RESET on power-up Accurate pretrimmed 5V outputs Reverse battery protection Overvoltage protection Reverse transient protection Short circuit protection Internal thermal overload protection ON OFF switch for high current outputs 100% electrical burn-in in thermal limit
Typical Application Circuit
LM2984C
Order Number LM2984CT See NS Package Number TA11B
COUT must be at least 10 mF to maintain stability May be increased without bound to maintain regulation during transients Locate as close as possible to the regulator This capac- TL H 8821 – 1 itor must be rated over the same operating temperature range as the regulator The equivalent series resistance (ESR) of this capacitor is critical see curve
C1995 National Semiconductor Corporation
TL H 8821
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Input Voltage Survival Voltage (k100 ms) Operational Voltage 35V 26V Internal Power Dissipation Operating Temperature Range (TA) Internally Limited 0 C to a 125 C Maximum Junction Temperature (Note 1) 150 C b 65 C to a 150 C Storage Temperature Range Lead Temperature (Soldering 10 sec ) 230 C ESD rating is to be determined
Electrical Characteristics
VIN e 14V IOUT e 5 mA COUT e 10 mF Tj e 25 C (Note 6) unless otherwise indicated Parameter VOUT (Pin 11) Output Voltage Line Regulation 5 mA s Io s 500 mA 6V s VIN s 26V 9V s VIN s 16V 7V s VIN s 26V Load Regulation Output Impedance Quiescent Current 5 mA s IOUT s 500 mA 250 mAdc and 10 mArms fo e 120 Hz IOUT e 500 mA IOUT e 250 mA Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage fo e 120 Hz IOUT e 500 mA IOUT e 250 mA Current Limit Maximum Operational Input Voltage Maximum Line Transient Reverse Polarity Input Voltage DC Reverse Polarity Input Voltage Transient Continuous DC VOUT s 6V ROUT e 100X VOUT t b0 6V ROUT e 100X T s 100 ms ROUT e 100X 10 Hz–100 kHz IOUT e 100 mA 5 00 2 5 12 24 38 14 100 20 70 0 53 0 28 0 92 32 45
b 30 b 55
Conditions
Typical
Tested Limit (Note 2)
Design Limit (Note 3)
Units
4 85 5 15 25 50 50
4 75 5 25
Vmin Vmax mVmax mVmax mVmax mX
100 50
mAmax mAmax mV mV 1000 hr
60 0 80 0 50 0 75 26 35
b 15 b 35
dBmin 1 00 0 60 Vmax Vmax Amin 26 35
b 15 b 35
Vmin Vmin Vmin Vmin
2
Electrical Characteristics (Continued) VIN e 14V Ibuf e 5 mA Cbuf e 10 mF Tj e 25 C (Note 6) unless otherwise indicated
Parameter Vbuffer (Pin 10) Output Voltage Line Regulation 5 mA s Io s 100 mA 6V s VIN s 26V 9V s VIN s 16V 7V s VIN s 26V Load Regulation Output Impedance Quiescent Current Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage Current Limit Maximum Operational Input Voltage Maximum Line Transient Reverse Polarity Input Voltage DC Reverse Polarity Input Voltage Transient Continuous DC Vbuf s 6V Rbuf e 100X Vbuf t b0 6V Rbuf e 100X T s 100 ms Rbuf e 100X fo e 120 Hz Ibuf e 100 mA 5 mA s Ibuf s 100 mA 50 mAdc and 10 mArms Ibuf e 100 mA 10 Hz–100 kHz IOUT e 100 mA 5 00 2 5 15 200 80 100 20 70 0 35 0 23 32 45
b 30 b 55
Conditions
Typical
Tested Limit (Note 2)
Design Limit (Note 3)
Units
4 85 5 15 25 50 50
4 75 5 25
Vmin Vmax mVmax mVmax mVmax mX
15 0
mAmax mV mV 1000 hr
60 0 50 0 15 26 35
b 15 b 35
dBmin 0 60 Vmax Amin 26 35
b 15 b 35
Vmin Vmin Vmin Vmin
Electrical Characteristics
VIN e 14V Istby e 1 mA Cstby e 10 mF Tj e 25 C (Note 6) unless otherwise indicated Parameter Vstandby (Pin 9) Output Voltage Line Regulation 1 mA s I.