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.Aredesign 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 −55˚C ≤T
A
≤
+125˚C, and the LM305/LM305A is specified for 0˚C ≤T
A
≤
+70˚C.
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 Voltage Regulators
© 1999 National Semiconductor Corporation DS007755 www.national.com
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 −55˚C to +125˚C 0˚C to +70˚C 0˚C to +70˚C
Storage Temperature Range −65˚C to +150˚C 65˚C to +150˚C −65˚C to +150˚C
Lead Temperature (Soldering, 10 seconds) 300˚C 300˚C 300˚C
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
=10Ω,T
A
=25˚C 0.02 0.05 0.02 0.05 %
(Note 3) R
SC
=10Ω,T
A
=T
A(MAX)
0.03 0.1 0.03 0.1 %
R
SC
=10Ω,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
=0Ω,T
A
=25˚C 0.02 0.2 %
R
SC
=0Ω,T
A
=70˚C 0.03 0.4 %
R
SC
=0Ω,T
A
=0˚C 0.03 0.4 %
0≤I
O
≤45 mA
Line Regulation T
A
=25˚C %/V
0˚C ≤T
A
≤+70˚C %/V
V
IN
−V
OUT
≤5V, T
A
=25˚C 0.025 0.06 0.025 0.06 0.025 0.06 %/V
V
IN
−V
OUT
≥5V, T
A
=25˚C 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 µF 0.002 0.002 0.002 %
Standby Current Drain V
IN
=30V, T
A
=25˚C 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
=25˚C, R
SC
=10Ω, 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 µF, f =120 Hz 0.003 0.003 0.003 %/V
θ
JA
TO-99 Board Mount 230 230 230 ˚C/W
in Still Air
θ
JA
TO-99 Board Mount in 92 92 92 ˚C/W
400 LF/Min Air Flow
θ
JC
TO-99 25 25 25 ˚C/W
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Electrical Characteristics (Note 2) (Continued)
Note 1: The maximum junction temperature of the LM105 and LM305A is 150˚C, and the LM305 is 85˚C. For operation at elevated temperatures, devices in the
H08C package must be derated based on a thermal resistance of 168˚C/W junction to ambient, or 25˚C/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 kΩ. 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
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Load Regulation
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Current Limiting
Characteristics
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Current Limit Sense Voltage
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Short Circuit Current
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Optimum Divider Resistance
Values
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Minimum Input Voltage
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Regulator Dropout Voltage
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Supply Voltage Rejection
DS007755-23
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Typical Performance Characteristics (Continued)
Typical Applications
Minimum Output Voltage
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Standby Current Drain
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Transient Response
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10A Regulator with Foldback Current Limiting
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†Solid tantalum.
*Electrolytic
1.0A Regulator with Protective Diodes
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†Protects against shorted input or inductive leads on unregulated supply.
*Protects against input voltage reversal.
††Protects against output voltage reversal.
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Typical Applications (Continued)
Linear Regulator with Foldback Current Limiting
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Current Regulator
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Shunt Regulator
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Switching Regulator
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†Solid tantaium.
††125 turns =22 on Arnold
Engineering A262123-2 molybdenum permally core.
Basic Positive Regulator with Current Limiting
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Typical Applications (Continued)
1.0A Regulator with Protective Diodes
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†Protects against shorted input or inductive loads on unregulated supply.
*Protects against input voltage reversal.
††Protects against output voltage reversal.
Linear Regulator with Foldback Current Limiting
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Physical Dimensions inches (millimeters) unless otherwise noted
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Metal Can Package (H)
Order Number LM105H, LM105H/883, SMD #5962-8958801, LM305H or LM305AH
NS Package Number H08C
LM105/LM305/LM305A Voltage Regulators
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.