TL H 7785
LM145LM345
Negative
Three
Amp
Regulator
January 1995
LM145 LM345 Negative Three Amp Regulator
General Description
The LM145 is a three-terminal negative regulator with a
fixed output voltage of
b
5V and up to 3A load current capa-
bility This device needs only one external component
a
compensation capacitor at the output making it easy to ap-
ply Worst case guarantees on output voltage deviation due
to any combination of line load or temperature variation
assure satisfactory system operation
Exceptional effort has been made to make the LM145 im-
mune to overload conditions The regulator has current lim-
iting which is independent of temperature combined with
thermal overload protection Internal current limiting pro-
tects against momentary faults while thermal shutdown pre-
vents junction temperatures from exceeding safe limits dur-
ing prolonged overloads
Although primarily intended for fixed output voltage applica-
tions the LM145 may be programmed for higher output volt-
ages with a simple resistive divider The low quiescent drain
current of the device allows this technique to be used with
good regulation
The LM145 comes in a hermetic TO-3 package rated at
25W A reduced temperature range part LM345 is also avail-
able
Features
Y
Output voltage accurate to better than
g
2%
Y
Current limit constant with temperature
Y
Internal thermal shutdown protection
Y
Operates with input-output voltage differential of 2 8V at
full rated load over full temperature range
Y
Regulation guaranteed with 25W power dissipation
Y
3A output current guaranteed
Y
Only one external component needed
Y
P
a
Product Enhancement tested
Schematic Diagram
TL H 7785 1
C1995 National Semiconductor Corporation
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
(Note 3)
Input Voltage
20V
Input-Output Differential
20V
Power Dissipation
Internally Limited
Operating Junction Temperature Range
LM145
b
55 C to
a
150 C
LM345
0 C to
a
125 C
Storage Temperature Range
b
65 C to
a
150 C
Lead Temperature (Soldering 10 sec )
300 C
Electrical Characteristics
(Note 1)
Limits
Parameter
Conditions
LM145
LM345
Units
Min
Typ
Max
Min
Typ
Max
Output Voltage
T
j
e
25 C I
OUT
e
5 mA
b
5 1
b
5 0
b
4 9
b
5 2
b
5 0
b
4 8
V
V
IN
e b
7 5
Line Regulation (Note 2)
T
j
e
25 C
5
15
5
25
mV
b
20V
s
V
IN
s
b
7 5V
Load Regulation (Note 2)
T
j
e
25 C V
IN
e b
7 5V
30
75
30
100
mV
5 mA
s
I
OUT
s
3A
Output Voltage
b
20V
s
V
IN
s
b
7 8V
5 mA
s
I
OUT
s
3A
P
s
25W
b
5 20
b
4 80
b
5 25
b
4 75
V
T
MIN
s
T
j
s
T
MAX
Quiescent Current
b
20V
s
V
IN
s
b
7 5V
1 0
3 0
1 0
3 0
mA
5 mA
s
I
OUT
s
3A
Short Circuit Current
V
IN
e b
7 5V T
j
e a
25 C
4
5 5
4
5 5
A
V
IN
e b
20V T
j
e a
25 C
2
3 5
2
3 5
A
Output Noise Voltage
T
A
e
25 C C
L
e
4 7 mF
150
150
m
V
10 Hz
s
f
s
100 kHz
Long Term Stability
5
50
5
50
mV
Thermal Resistance
2
2
C W
Junction to Case
Note 1
Unless otherwise specified these specifications apply
b
55 C
s
T
j
s a
150 C for the LM145 and 0 C
s
T
j
s a
125 C for the LM345 V
IN
e
7 5V and
I
OUT
e
5 mA Although power dissipation is internally limited electrical specifications apply only for power levels up to 25W For calculations of junction
temperature rise due to power dissipation use a thermal resistance of 35 C W for the TO-3 with no heat sink With a heat sink use 2 C W for junction to case
thermal resistance
Note 2
Regulation is measured at constant junction temperature Changes in output voltage due to heating effects must be taken into account separately To
ensure constant junction temperature pulse testing with a low duty cycle is used
Note 3
Refer to RETS145K-5V for LM145K-5 0 military specifications
Connection Diagram
Metal Can Package
TL H 7785 2
Bottom View
Order Number LM345K-5 0
See NS Package Number K02A
Order Number LM145K-5 0 883 or
SMD
5962-9064501
See NS Package Number K02C
Typical Applications
Fixed Regulator
TL H 7785 3
Required for stability For value given capacitor must be solid tantalum
50 mF aluminum electrolytic may be substituted Values given may be in-
creased without limit
Required if regulator is separated from filter capacitor For value given ca-
pacitor must be solid tantulum 50 mF aluminum electrolytic may be substi-
tuted
2
Typical Performance Characteristics
Dissipation for LM145
Maximum Average Power
Dissipation for LM345
Maximum Average Power
Ripple Rejection
Output Impedance
Voltage Differential
Minimum Input-Output
Temperature
Output Voltage vs
TL H 7785 4
Typical Applications
(Continued)
TL H 7785 5
Select resistors to set output voltage 1 ppm C tracking suggested
C1 is not needed if power supply filter capacitor is within 3
of regulator
Determines zener current May be adjusted to minimize temperature drift
Solid tantalum
Load and line regulation
k
0 01%
Temperature drift
k
0 001% C
3
Typical Applications
(Continued)
High Stability Regulator
TL H 7785 6
C1 is not needed if power supply filter capacitor is within 3
of regulator
Keep C4 within 2
of LM345
D2 sets initial output voltage accuracy The LM113 is available in
b
5
b
2 and
b
1% tolerance
b
2V ECL Termination Regulator
Dual 3 Amp Trimmed Supply
TL H 7785 7
Variable Output (
b
5 0V to
b
15V)
TL H 7785 8
Optional Improves transient
V
OUT
e b
5V
R1
a
R2
R2
J
response and ripple rejection
4
Physical Dimensions
inches (millimeters)
Metal Can Package (K)
Order Number LM345K-5 0
NS Package Number K02A
5
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