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PDF LM196 Data sheet ( Hoja de datos )
| Número de pieza | LM196 | |
| Descripción | LM196/LM396 10 Amp Adjustable Voltage Regulator | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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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 lev-
els up to 70 watts The regulators feature on-chip trimming
of reference voltage to g0 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 ex-
tremely low levels by strict attention to isothermal layout
This interaction called thermal regulation is 100% tested
These new regulators have all the protection features of
popular lower power adjustable regulators such as LM117
and LM138 including current limiting and thermal limiting
The combination of these features makes the LM196 im-
mune 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
conditions
Output voltage is continuously adjustable from 1 25V to
15V Higher output voltages are possible if the maximum
input-output voltage differential specification is not exceed-
ed Full load current of 10A is available at all output volt-
ages subject only to the maximum power limit of 70W and
of course maximum junction temperature
The LM196 is exceptionally easy to use Only two external
resistors are used to to set output voltage On-chip adjust-
ment of the reference voltage allows a much tighter specifi-
cation 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 require-
ments are much less stringent because overload situations
do not have to be accounted for only worst-case full load
conditions
The 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 a150 C The
LM396 is specified for a 0 C to a125 C junction tempera-
ture range
Features
Y Output pre-trimmed to g0 8%
Y 10A guaranteed output current
Y Pa Product Enhancement tested
Y 70W maximum power dissipation
Y Adjustable output 1 25V to 15V
Y Internal current and power limiting
Y Guaranteed thermal resistance
Y Output voltage guaranteed under worst-case conditions
Y Output is short circuit protected
Typical Applications
JR1 a R2
VOUT e (1 25V) R1 a IADJ (R2)
For best TC of VOUT R1 should be wirewound
or metal film 1% or better
R2 should be same type as R1 with TC track-
ing of 30 ppm C or better
C1 is necessary only if main filter capacitor is
more than 6 away assuming 18 or larger
leads
C2 is not absolutely necessary but is suggest-
ed to lower high frequency output impedance
Output capacitors in the range of 1 mF to
1000 mF of aluminum or tantalum electrolytic
are commonly used to provide improved out-
put impedance and rejection of transients
C3 improves ripple rejection output imped-
ance and noise C2 should be 1 mF or larger
close to the regulator if C3 is used
TL H 9059 – 1
FIGURE 1 Basic 1 25V to 15V Regulator
C1995 National Semiconductor Corporation TL H 9059
RRD-B30M115 Printed in U S A
1 page  
Application Hints (Continued)
Although it may not be immediately obvious best load regu-
lation is obtained when the top of the divider is connected
directly to the output pin not to the load This is illustrated in
Figure 2 If R1 were connected to the load the effective
resistance between the regulator and the load would be
JR2 a R1
(Rw) c
R1
Rw e Line Resistance
Connected as shown Rw is not multiplied by the divider
ratio Rw is about 0 004X per foot using 16 gauge wire This
translates to 40 mV ft at 10A load current so it is important
to keep the positive lead between regulator and load as
short as possible
TL H 9059 – 2
FIGURE 2 Proper Divider Connection
The input resistance of the sense pin is typically 6 kX mod-
eled as a resistor between the sense pin and the output pin
Load regulation will start to degrade if a resistance higher
than 10X is inserted in series with the sense This assumes
a worst-case condition of 0 5V between output and sense
pins Lower differential voltage will allow higher sense series
resistance
Thermal Load Regulation
Thermal as well as electrical load regulation must be con-
sidered with IC regulators Electrical load regulation occurs
in microseconds thermal regulation due to die thermal gra-
dients occurs in the 0 2 ms-20 ms time frame and regula-
tion due to overall temperature changes in the die occurs
over a 20 ms to 20 minute period depending on the time
constant of the heat sink used Gradient induced load regu-
lation is calculated from
DVOUT e (VIN b VOUT) c (DIOUT) c (b)
b e Thermal regulation specified on data sheet
For VIN e 9V VOUT e 5V DIOUT e 10A and b e
0 005% W this yields a 0 2% change in output voltage
Changes in output voltage due to overall temperature rise
are calculated from
VOUT e (VINb VOUT) c (DIOUT) c (TC) c (ijA)
TC e Temperature coefficient of output voltage
ijA e Thermal resistance from junction to ambient ijA is
approximately 0 5 C W a i of heat sink
For the same conditions as before with TC e 0 003% C
and ijA e 1 5 C W the change in output voltage will be
0 18% Because these two thermal terms can have either
polarity they may subtract from or add to electrical load
regulation For worst-case analysis they must be assumed
to add If the output of the regulator is trimmed under load
only that portion of the load that changes need be used in
the previous calculations significantly improving output ac-
curacy
Line Regulation
Electrical line regulation is very good on the LM196 typi-
cally less than 0 005% change in output voltage for a 1V
change in input This level of regulation is achieved only for
very low load currents however because of thermal ef-
fects Even with a thermal regulation of 0 002% W and a
temperature coefficient of 0 003% C DC line regulation
will be dominated by thermal effects as shown by the follow-
ing example
Assume VOUT e 5V VIN e 9V IOUT e 8A
Following a 10% change in input voltage (0 9) the output
will change quickly (s100 ms) due to electrical effects by
(0 005%V) c (0 9V) e 0 0045% In the next 20 ms the
output will change an additional (0 002% W) c (8A) c
(0 9V) e 0 0144% due to thermal gradients across the die
After a much longer time determined by the time constant
of the heat sink the output will change an additional
(0 003% C) c (8A) c (0 9V) c (2 C W) e 0 043% due to
the temperature coefficient of output voltage and the ther-
mal resistance from die to ambient (2 C W was chosen for
this calculation) The sign of these last two terms varies
from part to part so no assumptions can be made about any
cancelling effects All three terms must be added for a prop-
er analysis This yields 0 0045 a 0 0144 a 0 043 e
0 062% using typical values for thermal regulation and tem-
perature coefficient For worst-case analysis the maximum
data sheet specifications for thermal regulation and temper-
ature coefficient should be used along with the actual ther-
mal resistance of the heat sink being used
Paralleling Regulators
Direct paralleling of regulators is not normally recommend-
ed because they do not share currents equally The regula-
tor with the highest reference voltage will supply all the cur-
rent to the load until it current limits With an 18A load for
instance one regulator might be operating in current limit at
16A while the second device is only carrying 2A Power dis-
sipation in the high current regulator is extremely high with
attendant high junction temperatures Long term reliability
cannot be guaranteed under these conditions
Quasi-paralleling may be accomplished if load regulation is
not critical The connection shown in Figure 5a will typically
share to within 1A with a worst-case of about 3A Load
regulation is degraded by 150 mV at 20A loads An external
op amp may be used as in Figure 5b to improve load regula-
tion and provide remote sensing
5
5 Page 
Typical Applications (Continued)
Parasatic line resistance created by wiring
connectors or parallel ballasting
FIGURE 7 Correcting for Line Losses
TL H 9059 – 15
Power NPNs have low collecter resistance and do not require collector bond wires Collectors are all common to substrate
Standard NPNs are still isolated
FIGURE 8 Process Technology
TL H 9059 – 16
Connection Diagram
Metal Can Package
Bottom View
TL H 9059 – 18
Order Number LM196K STEEL or LM396K STEEL
See NS Package Number K02B
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet LM196.PDF ] | |
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