LM105/LM305/LM305A
Voltage Regulators
General Description
The LM105 series are positive voltage regulators similar to
the LM100, except that an extra gain stage has been added
for improved regulation. A redesign of the biasing circuitry re-
moves any minimum load current requirement and at the
same time reduces standby current drain, permitting higher
voltage operation. They are direct, plug-in replacements for
the LM100 in both linear and switching regulator circuits with
output voltages greater than 4.5V. Important characteristics
of the circuits are:
Output voltage adjustable from 4.5V to 40V
Output currents in excess of 10A possible by adding ex-
ternal transistors
Load regulation better than 0.1%, full load with current
limiting
DC line regulation guaranteed at 0.03%/V
Ripple rejection on 0.01%V
45 mA output current without external pass transistor
(LM305A)
Like the LM100, they also feature fast response to both load
and line transients, freedom from oscillations with varying re-
sistive and reactive loads and the ability to start reliably on
any load within rating. The circuits are built on a single silicon
chip and are supplied in a TO-99 metal can.
The LM105 is specified for operation for -55C
T
A
+125C, and the LM305/LM305A is specified for 0C
T
A
+70C.
Schematic and Connection Diagrams
DS007755-1
Metal Can Package
DS007755-3
Top View
Order Number LM105H, LM105H/883,
SMD #5962-8958801, LM305H or LM305AH
See NS Package Number H08C
June 1999
LM105/LM305/LM305A
V
oltage
Regulators
1999 National Semiconductor Corporation
DS007755
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Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
(Note 5)
LM105
LM305
LM305A
Input Voltage
50V
40V
50V
Input-Output Differential
40V
40V
40V
Power Dissipation (Note 1)
800 mW
800 mW
800 mW
Operating Temperature Range
-55C to +125C
0C to +70C
0C to +70C
Storage Temperature Range
-65C to +150C
65C to +150C
-65C to +150C
Lead Temperature (Soldering, 10 seconds)
300C
300C
300C
Electrical Characteristics
(Note 2)
Parameter
Conditions
LM105
LM305
LM305A
Units
Min
Typ
Max
Min
Typ
Max
Min
Typ
Max
Input Voltage Range
8.5
50
8.5
40
8.5
50
V
Output Voltage Range
4.5
40
4.5
30
4.5
40
V
Input-Output Voltage
3.0
30
3.0
30
3.0
30
V
Differential
Load Regulation
R
SC
= 10
, T
A
= 25C
0.02
0.05
0.02
0.05
%
(Note 3)
R
SC
= 10
, T
A
= T
A(MAX)
0.03
0.1
0.03
0.1
%
R
SC
= 10
, T
A
= T
A(MIN)
0.03
0.1
0.03
0.1
%
0
I
O
12 mA
0
I
O
12 mA
R
SC
= 0
, T
A
= 25C
0.02
0.2
%
R
SC
= 0
, T
A
= 70C
0.03
0.4
%
R
SC
= 0
, T
A
= 0C
0.03
0.4
%
0
I
O
45 mA
Line Regulation
T
A
= 25C
%/V
0C
T
A
+70C
%/V
V
IN
- V
OUT
5V, T
A
= 25C
0.025
0.06
0.025
0.06
0.025
0.06
%/V
V
IN
- V
OUT
5V, T
A
= 25C
0.015
0.03
0.015
0.03
0.015
0.03
%/V
Temperature Stability
T
A(MIN)
T
A
T
A(MAX)
0.3
1.0
0.3
1.0
0.3
1.0
%
Feedback Sense
Voltage
1.63
1.7
1.81 1.63
1.7
1.81 1.55
1.7
1.85
V
Output Noise Voltage
10 Hz
f
10 kHz
C
REF
= 0
0.005
0.005
0.005
%
C
REF
= 0.1 F
0.002
0.002
0.002
%
Standby Current Drain
V
IN
= 30V, T
A
= 25C
mA
V
IN
= 40V
0.8
2.0
mA
V
IN
= 50V
0.8
2.0
0.8
2.0
mA
Current Limit
T
A
= 25C, R
SC
= 10
,
225
300
375
225
300
375
225
300
375
mV
Sense Voltage
V
OUT
= 0V, (Note 4)
Long Term Stability
0.1
0.1
0.1
%
Ripple Rejection
C
REF
= 10 F, f = 120 Hz
0.003
0.003
0.003
%/V
JA
TO-99 Board Mount
230
230
230
C/W
in Still Air
JA
TO-99 Board Mount in
92
92
92
C/W
400 LF/Min Air Flow
JC
TO-99
25
25
25
C/W
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2
Electrical Characteristics
(Note 2) (Continued)
Note 1: The maximum junction temperature of the LM105 and LM305A is 150C, and the LM305 is 85C. For operation at elevated temperatures, devices in the
H08C package must be derated based on a thermal resistance of 168C/W junction to ambient, or 25C/W junction to case. Peak dissipations to 1W are allowable
providing the dissipation rating is not exceeded with the power average over a five second interval for the LM105 and averaged over a two second interval for the
LM305.
Note 2: Unless otherwise specified, these specifications apply for temperatures within the operating temperature range, for input and output voltages within the
range given, and for a divider impedance seen by the feedback terminal of 2 k
. Load and line regulation specifications are for a constant junction temperature. Tem-
perature drift effects must be taken into account separately when the unit is operating under conditions of high dissipation.
Note 3: The output currents given, as well as the load regulation, can be increased by the addition of external transistors. The improvement factor will be roughly
equal to the composite current gain of the added transistors.
Note 4: With no external pass transistor.
Note 5: Refer to RETS105X Drawing for military specifications for the LM105.
Typical Performance Characteristics
Load Regulation
DS007755-15
Load Regulation
DS007755-16
Current Limiting
Characteristics
DS007755-17
Current Limit Sense Voltage
DS007755-18
Short Circuit Current
DS007755-19
Optimum Divider Resistance
Values
DS007755-20
Minimum Input Voltage
DS007755-21
Regulator Dropout Voltage
DS007755-22
Supply Voltage Rejection
DS007755-23
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3
Typical Performance Characteristics
(Continued)
Typical Applications
Minimum Output Voltage
DS007755-24
Standby Current Drain
DS007755-25
Transient Response
DS007755-26
10A Regulator with Foldback Current Limiting
DS007755-4
Solid tantalum.
*Electrolytic
1.0A Regulator with Protective Diodes
DS007755-5
Protects against shorted input or inductive leads on unregulated supply.
*Protects against input voltage reversal.
Protects against output voltage reversal.
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4
Typical Applications
(Continued)
Linear Regulator with Foldback Current Limiting
DS007755-8
Current Regulator
DS007755-9
Shunt Regulator
DS007755-10
Switching Regulator
DS007755-11
Solid tantaium.
125 turns =22 on Arnold
Engineering A262123-2 molybdenum permally core.
Basic Positive Regulator with Current Limiting
DS007755-12
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5
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