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Part: LM396K
Category:
Power Management
-> Regulators
-> Voltage Regulators
-> Adjustable
Description: 10 Amp Adjustable Voltage Regulator
Company: National Semiconductor Corporation
Datasheet: Download LM396K datasheet File size : 4 kB
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Datasheet text preview:
LM196 LM396 10 Amp Adjustable Voltage Regulator
August 1992
LM196 LM396 10 Amp Adjustable Voltage Regulator
General Description
The LM196 is a 10 amp regulator adjustable from 1 25V to 15V which uses a revolutionary new IC fabrication structure to combine high power discrete transistor technology with modern monolithic linear IC processing This combination yields a high-performance single-chip regulator capable of supplying in excess of 10 amps and operating at power levels up to 70 watts The regulators feature on-chip trimming of reference voltage to g 0 8% and simultaneous trimming of reference temperature drift to 30 ppm C typical Thermal interaction between control circuitry and the pass transistor which affects the output voltage has been reduced to exT tremely low levels by strict attention to isothermal layout This interaction called thermal regulation is 100% tested hese new regulators have all the protection features of popular lower power adjustable regulators such as LM117 T and LM138 including current limiting and thermal limiting he combination of these features makes the LM196 immune to blowout from output overloads or shorts even if the adjustment pin is accidentally disconnected All devices are ``burned-in'' in thermal shutdown to guarantee proper operation of these protective features under actual overload O conditions utput voltage is continuously adjustable from 1 25V to 15V Higher output voltages are possible if the maximum input-output voltage differential specification is not exceeded Full load current of 10A is available at all output voltages subject only to the maximum power limit of 70W and of course maximum junction temperature he LM196 is exceptionally easy to use Only two external resistors are used to to set output voltage On-chip adjustment of the reference voltage allows a much tighter specification of output voltage eliminating any need for trimming in most cases The regulator will tolerate an extremely wide range of reactive loads and does not depend on external capacitors for frequency stabilization Heat sink requirements are much less stringent because overload situations do not have to be accounted for only worst-case full load T conditions he LM196 is in a TO-3 package with oversized (0 060 ) leads to provide best possible load regulation Operating junction temperature range is b55 C to a 150 C The LM396 is specified for a 0 C to a 125 C junction temperaFre range tu
eatures
Y Y Y Y Y Y Y Y Y
Output pre-trimmed to g 0 8% 10A guaranteed output current P a Product Enhancement tested 70W maximum power dissipation Adjustable output 1 25V to 15V Internal current and power limiting Guaranteed thermal resistance Output voltage guaranteed under worst-case conditions Output is short circuit protected
T
Typical Applications
VOUT e (1 25V)
R1 a R2 R1
J
a IADJ (R2)
For best TC of VOUT R1 should be wirewound R or metal film 1% or better 2 should be same type as R1 with TC tracking of 30 ppm C or better C 1 is necessary only if main filter capacitor is more than 6 away assuming 18 or larger C ads le 2 is not absolutely necessary but is suggestO ed to lower high frequency output impedance utput capacitors in the range of 1 mF to 1000 mF of aluminum or tantalum electrolytic are commonly used to provide improved output impedance and rejection of transients C 3 improves ripple rejection output impedance and noise C2 should be 1 mF or larger close to the regulator if C3 is used
F
TL H 9059 1
IGURE 1 Basic 1 25V to 15V Regulator
C1995 National Semiconductor Corporation
TL H 9059
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
p If Military Aerospace specified devices are required lease contact the National Semiconductor Sales P Office Distributors for availability and specifications ower Dissipation Input-Output Voltage Differential Operating Junction Temperature Range LM196 Control Section Power Transistor LM396 Control Section Power Transistor
b 55 b 55
Storage Temperature ESD rating to be determined
b 65
Lead Temperature (Soldering 10 seconds)
C to a 150 C 300 C
Internally Limited 20V
C to a 150 C C to a 200 C 0 C to a 125 C 0 C to a 175 C
Electrical Characteristics (Note 1)
Parameter Reference Voltage Reference Voltage (Note 2) Line Regulation (Note 3) Load Regulation LM196 LM396 (Note 4) Ripple Rejection (Note 5) Thermal Regulation (Note 6) Average Output Voltage Temperature Coefficient Adjustment Pin Current Adjustment Pin Current Change (Note 7) Minimum Load Current (Note 9) Current Limit (Note 8) Rms Output Noise Long Term Stability Thermal Resistance Junction to Case (Note 10) 10 mA s IOUT s 10A 3V s VIN b VOUT s 20V P s PMAX Full Temperature Range 2 5V s (VIN b VOUT) s 20V Full Temperature Range 2 5 s (VIN b VOUT s 7V VIN b VOUT e 20V 10 Hz s f s 10 kHz Tj e 125 C t e 1000 Hours Control Circuitry Power Transistor 10 15 14 3 0 001 03 03 10 10 05 12 10 20 8 10 15 14 3 0 001 03 03 10 10 05 12 10 20 8 mA A A %VOUT % Conditions Min IOUT e 10 mA VMIN s (VIN b VOUT) s 20V 10 mA s IOUT 10A P s PMAX Full Temperature Range VMIN s (VIN b VOUT) s 20V Full Temperature Range 10 mA s IOUT s 10A VMIN s VIN b VOUT s 10V P s PMAX Full Temperature Range CADJ e 25 mF f e 120 Hz Full Temperature Range VIN b VOUT e 5V IOUT e 10A TjMIN s Tj s TjMAX (See Curves for Limits) 60 54 74 0 003 0 003 50 100 3 0 005 1 24 1 22 LM196 Typ 1 25 1 25 Max 1 26 1 28 Min 1 23 1 21 LM396 Typ 1 25 1 25 Max 1 27 1 29 V V Units
0 005
0 01 0 05 01 0 15 66 54
0 005
0 02 0 05 01 0 15
%V %V %A %A dB dB
74 0 003 0 003 50 100 3 0 015
%W %C mA mA
CW CW
2
Electrical Characteristics (Note 1) (Continued)
Parameter Power Dissipation (PMAX) (Note 11) Drop-Out Voltage LM196 LM396 Conditions Min 7 0V s VIN b VOUT s 12V VIN b VOUT e 15V VIN b VOUT e 18V IOUT e 10A Full Temperature Range 70 50 36 LM196 Typ 100 Max Min 70 50 36 25 2 75 LM396 Typ 100 Max W W W 25 2 75 V Units
21
21
Note 1 Unless otherwise stated these specifications apply for Tj e 25 C VIN b VOUT e 5V IOUT e 10 mA to 10A ote 2 This is a worst-case specification which includes all effects due to input voltage output current temperature and power dissipation Maximum power (P N MAX) is specified under Electrical Characteristics ote 3 Line regulation is measured on a short-pulse low-duty-cycle basis to maintain constant junction temperature Changes in output voltage due to thermal N gradients or temperature changes must be taken into account separately See discussion of Line Regulation under Application Hints ote 4 Load regulation on the 2-pin package is determined primarily by the voltage drop along the output pin Specifications apply for an external Kelvin sense connnection at a point on the output pin from the bottom of the package Testing is done on a short-pulse-width low-duty-cycle basis to maintain constant junction temperature Changes in output voltage due to thermal gradients or temperature changes must be taken into account separately See discussion of Load N Regulation under Application Hints ote 5 Ripple rejection is measured with the adjustment pin bypassed with 25 mF capacitor and is therefore independent of output voltage With no load or bypass capacitor ripple rejection is determined by line regulation and may be calculated from RR e 20 log10 100 (K c VOUT) where K is line regulation N expressed in % V At frequencies below 100 Hz ripple rejection may be limited by thermal effects if load current is above 1A d ote 6 Thermal regulation is defined as the change in output voltage during the time period of 0 2 ms to 20 ms after a change in power dissipation in the regulator Nue to either a change in input voltage or output current See graphs and discussion of thermal effects under Application Hints ote 7 Adjustment pin current change is specified for the worst-case combination of input voltage output current and power dissipation Changes due to N temperature must be taken into account separately See graph of adjustment pin current vs temperature t ote 8 Current limit is measured 10 ms after a short is applied to the output DC measurements may differ slightly due to the rapidly changing junction temperature ending to drop slightly as temperature increases A minimum available load current of 10A is guaranteed over the full temperature range as long as power dissipation does not exceed 70W and VIN b VOUT is less than 7 0V Note 9 Minimum load current of 10 mA is normally satisfied by the resistor divider which sets up output voltage ote 10 Total thermal resistance junction-to-ambient will include junction-to-case thermal resistance plus interface resistance and heat sink resistance See N discussion of Heat Sinking under Application Hints ote 11 Although power dissipation is internally limited electrical specifications apply only for power dissipation up to the limits shown Derating with temperature is a function of both power transistor temperature and control area temperature which are specified differently See discussion of Heat Sinking under Application H Nints For VIN b VOUT less than 7V power dissipation is limited by current limit of 10A ote 12 Dropout voltage is input-output voltage differential measured at a forced reference voltage of 1 15V with a 10A load and is a measurement of the A imum input output differential at full load min
pplication Hints
Further improvements in efficiency can be obtained by using Schottky diodes or high efficiency diodes with lower forward voltage combined with larger filter capacitors to reduce ripple However this reduces the voltage difference between input and drive pins and may not allow sufficient voltage to fully saturate the pass transistor Special transformers are available from Signal Transformer that have a 1V tap on the T output winding to provide the extra voltage for the drive pin he transformers are available as standard items for 5V applications at 5A 10A and 20A Other voltages are available H on special request eat Sinking t Because of its extremely high power dissipation capability he major limitation in the load driving capability of the LM196 is heat sinking Previous regulators such as LM109 M340 LM117 etc had internal power limiting circuitry which limited power dissipation to about 30W The LM196
3
is guaranteed to dissipate up to 70W continuously as long T as the maximum junction temperature limit is not exceeded his requires careful attention to all sources of thermal resistance from junction-to-ambient including junction-tocase resistance case-to-heat sink interface resistance (0 1 1 0 C W) and heat sink resistance itself A good thermal joint compound such as Wakefield type 120 or Thermale loy Thermocote must be used when mounting the LM196 specially if an electrical insulator is used to isolate the regulator from the heat sink Interface resistance without this compound will be no better than 0 5 C W and probably much worse With the compound and no insulator interface resistance will be 0 2 C W or less assuming 0 005 or less combined flatness run-out of TO-3 and heat sink Proper torquing of the mounting bolts is important to achieve minimum thermal resistance Four to six inch pounds is recommended Keep in mind that good electrical as well as thermal contact must be made to the case
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