© Semiconductor Components Industries, LLC, 2006
August, 2006 − Rev. 4 1Publication Order Number:
LM350/D
LM350
3.0 A, Adjustable Output,
Positive Voltage Regulator
The LM350 is an adjustable three−terminal positive voltage
regulator capable of supplying in excess of 3.0 A over an output
voltage range of 1.2 V to 33 V. This voltage regulator is
exceptionally easy to use and requires only two external resistors to
set the output voltage. Further, it employs internal current limiting,
thermal shutdown and safe area compensation, making it essentially
blow−out proof.
The LM350 serves a wide variety of applications including local,
on card regulation. This device also makes an especially simple
adjustable switching regulator, a programmable output regulator, or
by connecting a fixed resistor between the adjustment and output, the
LM350 can be used as a precision current regulator.
Features
•Guaranteed 3.0 A Output Current
•Output Adjustable between 1.2 V and 33 V
•Load Regulation Typically 0.1%
•Line Regulation Typically 0.005%/V
•Internal Thermal Overload Protection
•Internal Short Circuit Current Limiting Constant with Temperature
•Output Transistor Safe Area Compensation
•Floating Operation for High Voltage Applications
•Standard 3−lead Transistor Package
•Eliminates Stocking Many Fixed Voltages
•Pb−Free Packages are Available*
Figure 1. Simplified Application
* = Cin is required if regulator is located an appreciable distance from power supply filter.
** = CO is not needed for stability, however, it does improve transient response.
S
ince IAdj is controlled to less than 100 mA, the error associated with this term is negligible in most application
s
LM350
Vin vout
R1
240
R2
Adjust
IAdj
Cin*
0.1mF
+CO**
1mF
Vout +1.25 V ǒ1)R2
R1Ǔ)IAdj R2
*For additional information on our Pb−Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques Reference
Manual, SOLDERRM/D.
TO−220
T SUFFIX
PLASTIC PACKAGE
CASE 221AB
THREE−TERMINAL
ADJUSTABLE POSITIVE
VOLTAGE REGULATOR
123
See detailed ordering and shipping information in the package
dimensions section on page 3 of this data sheet.
ORDERING INFORMATION
MARKING DIAGRAM
350T
A = Assembly Location
WL = Wafer Lot
Y = Year
WW = W ork Week
G = Pb−Free Device
AWLYWWG
LM
Pin 1. Adjust
2. Vout
3. Vin
Heatsink surface is connected to Pin 2.
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LM350
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2
MAXIMUM RATINGS
Rating Symbol Value Unit
Input−Output Voltage Dif ferential VI−VO35 Vdc
Power Dissipation PDInternally Limited W
Operating Junction Temperature Range TJ−40 to +125 °C
Storage Temperature Range Tstg −65 to +150 °C
Soldering Lead Temperature (10 seconds) Tsolder 300 °C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
ELECTRICAL CHARACTERISTICS (VI−VO = 5.0 V; IL = 1.5 A; TJ = Tlow to Thigh; Pmax [Note 1], unless otherwise noted.)
Characteristics Figure Symbol Min Typ Max Unit
Line Regulation (Note 2) TA = 25°C, 3.0 V ≤ VI−VO ≤ 35 V 1 Regline − 0.0005 0.03 %/V
Load Regulation (Note 2)
TA = 25°C, 10 mA ≤ Il ≤ 3.0 A
VO ≤ 5.0 V
VO ≥ 5.0 V
2 Regload
−
−5.0
0.1 25
0.5 mV
% VO
Thermal Regulation, Pulse = 20 ms, (TA = +25°C) Regtherm − 0.002 − % VO/W
Adjustment Pin Current 3 IAdj − 50 100 mA
Adjustment Pin Current Change
3.0 V ≤ VI−VO ≤ 35 V
10 mA ≤ IL ≤ 3.0 A, PD ≤ Pmax
1,2 DIAdj − 0.2 5.0 mA
Reference Voltage
3.0 V ≤VI−VO ≤ 35 V
10 mA ≤ IO ≤ 3.0 A, PD ≤ Pmax
3 Vref 1.20 1.25 1.30 V
Line Regulation (Note 2) 3.0 V ≤VI−VO ≤ 35 V 1 Regline − 0.02 0.07 %/V
Load Regulation (Note 2)
10 mA ≤IL ≤3.0 A
VO ≤5.0 V
VO ≥ 5.0 V
2 Regload
−
−20
0.3 70
1.5 mV
% VO
Temperature Stability (Tlow ≤TJ ≤Thigh) 3 TS− 1.0 − % VO
Minimum Load Current to
Maintain Regulation (VI−VO = 35 V) 3 ILmin − 3.5 10 mA
Maximum Output Current
VI−VO ≤ 10 V, PD ≤ Pmax
VI−VO = 30 V, PD ≤Pmax, TA = 25°C
3 Imax 3.0
0.25 4.5
1.0 −
−
A
RMS Noise, % of VO
TA= 25°C, 10 Hz ≤f ≤10 kHz N − 0.003 − % VO
Ripple Rejection, VO = 10 V, f = 120 Hz (Note 3)
Without CAdj
CAdj = 10 mF
4 RR −
66 65
80 −
−
dB
Long Term Stability, TJ = Thigh (Note 4)
TA= 25°C for Endpoint Measurements 3 S − 0.3 1.0 %/1.0 k
Hrs.
Thermal Resistance, Junction−to−Case
Peak (Note 5)
Average (Note 6)
RqJC −
−2.3
−−
1.5
°C/W
1. Tlow to Thigh = 0° to +125°C; Pmax = 25 W for LM350T; Tlow to Thigh = −40° to +125°C; Pmax = 25 W for LM350BT
2. Load and line regulation are specified at constant junction temperature. Changes in VO due to heating effects must be taken into account
separately. Pulse testing with low duty cycle is used.
3. CAdj, when used, is connected between the adjustment pin and ground.
4. Since Long−Term Stability cannot be measured on each device before shipment, this specification is an engineering estimate of average
stability from lot to lot.
5. Thermal Resistance evaluated measuring the hottest temperature on the die using an infrared scanner. This method of evaluation yields very
accurate thermal resistance values which are conservative when compared to the other measurement techniques.
6. The average die temperature is used to derive the value of thermal resistance junction to case (average).
LM350
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ORDERING INFORMATION
Device Operating Temperature
Range Package Shipping†
LM350T TJ = 0°to + 125 °CTO−220 50 Units / Rail
LM350TG TO−220
(Pb−Free) 50 Units / Rail
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
Figure 2. Representative Schematic Diagram
310 310 230 120 5.6K
Vin
170
6.3V
160
12K
5.0pF
6.8K
13K
6.3V
105
4
0.45
Vout
Adjust
12.5K
2.4K
30
pF
30
pF
6.3V 125K
135
190
12.4K3.6K
5.8K
110
5.1K
6.7K
510
200
*Pulse Testing Required:
1% Duty Cycleis suggested.
Line Regulation (%/V) = VOH − VOL x 100
*
VCC
VIH
VIL Vin Vout
VOH
VOL
RL
+
1mFCO
240
1%
R1
Adjust
R2
1%
Cin 0.1mF
LM350
IAdj
IL
Figure 3. Line Regulation and DIAdj/Line Test Circuit
VOL
LM350
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*Pulse Testing Required:
1% Duty Cycle is suggested.
Load Regulation (mV) = VO (min Load) −VO (max Load)
Load Regulation (% VO) = VO (min Load) − VO (max Load) X 100
VO (min Load)
VO (max Load)
LM350
Cin 0.1mF
Adjust
R2
1%
CO1.0mF
+
*
RL
(max Load) RL
(min Load)
Vout
R1
240
1%
Vin Vin
IAdj
IL
Figure 4. Load Regulation and DI
Adj
/Load Test Circuit
VO (min Load)
Pulse Testing Required:
1% Duty Cycle is suggested.
LM350
Vin Vout
Adjust
R1240
1%
+
1.0mFCO
RL
Cin
R2
1%
To Calculate R2:
Vout = ISET R2 + 1.250 V
Assume ISET = 5.25 mA
IL
IAdj
ISET
Vref
VO
VI
0.1mF
Figure 5. Standard Test Circuit
LM350
Vin Vout Vout = 10 V
RL
Cin 0.1mF
Adjust R1240
1%
D1 *
1N4002
CO
+
1.0mF
24V
14V
R21.65K
1% CAdj 10mF
+
*D1 Discharges CAdj if Output is Shorted to Ground.
**CAdj provides an AC ground to the adjust pin.
f = 120 Hz
VO
IL
**
Figure 6. Ripple Rejection Test Circuit
LM350
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ref
V , REFERENCE VOLTAGE (V)
IB, QUIESCENT CURRENT (mA)
IAdj, ADJUSTMENT PIN CURRENT ( A)μVout , OUTPUT VOLTAGE CHANGE (%)Δ
Figure 7. Load Regulation Figure 8. Current Limit
Figure 9. Adjustment Pin Current Figure 10. Dropout Voltage
Figure 11. Temperature Stability Figure 12. Minimum Operating Current
0.4
0.2
0
−0.2
−0.4
−0.6
−0.8
−1.0
−75 −50 −25 0 25 50 75 100 125 150
TJ, JUNCTION TEMPERATURE (°C)
Vin = 15 V
Vout = 10 V
IL = 0.5 A
IL = 1.5 A
7
5
3
1
0010203040
Vin−Vout, INPUT VOLTAGE DIFFERENTIAL (Vdc)
Iout , OUTPUT CURRENT (A)
70
65
60
55
50
45
40
35
−75 −50 −25 0 25 50 75 100 125 150
TJ, JUNCTION TEMPERATURE (°C)
−75 −50 −25 0 25 50 75 100 125 150
TJ, JUNCTION TEMPERATURE (°C)
3.0
2.5
2.0
1.5
1.0
DV0 = 100 mV
IL = 3.0 A
IL = 2.0 A
IL = 500 mA
IL = 200 mA
IL = 20 mA
−75 −50 −25 0 25 50 75 100 125 150
TJ, JUNCTION TEMPERATURE (°C)
1.260
1.250
1.240
1.230
1.220
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
00 10 203040
Vin−Vout, INPUT−OUTPUT VOLTAGE DIFFERENTIAL (Vdc)
TJ = −55°C
TJ = 25°C
TJ = 150°C
TJ = 55°C
TJ = 150°C
TJ = 25°C
Vin−Vout, INPUT−OUTPUT VOLTAGE
DIFFERENTIAL (Vdc)
LM350
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Vout , OUTPUT VOLTAGEΔ
DEVIATION (V)
ZOΩ, OUTPUT IMPEDANCE ()
Vout , OUTPUT VOLTAGEΔ
DEVIATION (V)
Vin, INPUT VOLTAGEΔ
CHANGE (V)
Figure 13. Ripple Rejection versus Output Voltage Figure 14. Ripple Rejection versus Output Current
Figure 15. Ripple Rejection versus Frequency Figure 16. Output Impedance
Figure 17. Line Transient Response Figure 18. Load Transient Response
1.5
1.0
0.5
0
−0.5
−1.0
−1.5
1.0
0.5
0010203040
t, TIME (ms)
CL = 1.0 mF; CAdj = 10 mF
CL = 0; Without CAdj
Vin
Vout = 10 V
IL = 50 mA
TJ = 25°C
3
2
1
0
−1
−2
−3
1.5
1.0
0.5
0010203040
t, TIME (ms)
I
CURRENT (A)
L, LOAD
CL = 0; Without CAdj
CL = 1.0 mF; CAdj = 10 mF
Vin = 15 V
Vout = 10 V
INL = 50 mA
TJ = 25°C
IL
100
80
60
40
20
00 5 10 15 20 25 30 35
RR, RIPPLE REJECTION (dB)
Vout, OUTPUT VOLTAGE (V)
Vin − Vout = 5 V
IL = 500 mA
f = 120 Hz
TJ = 25°C
Without CAdj
CAdj = 10 mF120
100
80
60
40
20
0
0.01 0.1 1 10
Iout, OUTPUT CURRENT (A)
RR, RIPPLE REJECTION (dB)
Vin − Vout = 5 V
IL = 500 mA
f = 120 Hz
TJ = 25°C
Without CAdj
CAdj = 10 mF
Without CAdj
100
80
60
40
20
010 100 1.0 k 10 k 100 k 1.0 M 10 M
RR, RIPPLE REJECTION (dB)
f, FREQUENCY (Hz)
IL = 500 mA
Vin = 15 V
Vout = 10 V
TJ = 25°C
CAdj = 10 mF
Vin = 15 V
Vout = 10 V
IL = 500 mA
TJ = 25°C
CAdj = 10 mF
Without CAdj
101
100
10−1
10−2
10−3
10 100 1.0 k 10 k 100 k 1.0 M
f, FREQUENCY (Hz)
140
LM350
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APPLICATIONS INFORMATION
Basic Circuit Operation
The LM350 is a three−terminal floating regulator. In
operation, the LM350 develops and maintains a nominal
1.25 V reference (Vref) between its output and adjustment
terminals. This reference voltage is converted to a
programming current (IPROG) by R1 (see Figure 19), and
this constant current flows through R2 to ground. The
regulated output voltage is given by:
R2
Vout = Vref (1 + ) + IAdj R2
R1
Since the current from the terminal (IAdj) represents an
error term in the equation, the LM350 was designed to
control IAdj to less than 100 mA and keep it constant. To do
this, all quiescent operating current is returned to the output
terminal. This imposes the requirement for a minimum
load current. If the load current is less than this minimum,
the output voltage will rise.
Since the LM350 is a floating regulator, it is only the
voltage differential across the circuit which is important to
performance, and operation at high voltages with respect to
ground is possible.
+
Vref
Adjust
Vin Vout
LM350
R1
IPROG
Vout
R2
IAdj
Vref = 1.25 V Typical
Figure 19. Basic Circuit Configuration
Load Regulation
The LM350 is capable of providing extremely good load
regulation, but a few precautions are needed to obtain
maximum performance. For best performance, the
programming resistor (R1) should be connected as close to
the regulator as possible to minimize line drops which
effectively appear in series with the reference, thereby
degrading regulation. The ground end of R2 can be returned
near the load ground to provide remote ground sensing and
improve load regulation.
External Capacitors
A 0.1 mF disc or 1 mF tantalum input bypass capacitor
(Cin) is recommended to reduce the sensitivity to input line
impedance.
The adjustment terminal may be bypassed to ground to
improve ripple rejection. This capacitor (CAdj) prevents
ripple from being amplified as the output voltage is
increased. A 10 mF capacitor should improve ripple
rejection about 15 dB at 120 Hz in a 10 V application.
Although the LM350 is stable with no output
capacitance, like any feedback circuit, certain values of
external capacitance can cause excessive ringing. An
output capacitance (CO) in the form of a 1 mF tantalum or
25 mF aluminum electrolytic capacitor on the output
swamps this effect and insures stability.
Protection Diodes
When external capacitors are used with any IC regulator,
it is sometimes necessary to add protection diodes to
prevent the capacitors from discharging through low
current points into the regulator.
Figure 18 shows the LM350 with the recommended
protection diodes for output voltages in excess of 25 V or
high capacitance values (CO > 25 mF, CAdj > 10 mF). Diode
D1 prevents CO from discharging thru the IC during an
input short circuit. Diode D2 protects against capacitor
CAdj discharging through the IC during an output short
circuit. The combination of diodes D1 and D2 prevents CAdj
from discharging through the IC during an input short
circuit.
D1
Vin
Cin
1N4002
LM350
Vout
R1
+
CO
D2
R2CAdj
1N4002
Adjust
Figure 20. Voltage Regulator with
Protection Diodes
LM350
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Figure 21. “Laboratory” Power Supply with Adjustable Current Limit and Output Voltage
Figure 22. Adjustable Current Limiter Figure 23. 5.0 V Electronic Shutdown Regulator
Figure 24. Slow Turn−On Regulator Figure 25. Current Regulator
D6
1N4002
Vin
32V Vin1
LM350
(1)
Adjust 1
Vout1 RSC Vin2 Vout 2IO
VO
IN4001
1N4001
240 D5
1N4001
+
1.0mF
Tantalum
1K
Current
Limit
Adjust
Q1
2N3822
5.0K
Adjust 2
Voltage
Adjust
+
10mF
D3
D4
D1
1N4001
Q2
2N5640
−10V
Output Range:
0 ≤ VO ≤25 V
0 ≤ IO ≤1.5 A
Diodes D1 and D2 and transistor Q2 are added to allow adjustment
of output voltage to 0 V.
D6 protects both LM350’s during an input short circuit.
1N4001
D2
−10V
0.1mF
LM350
(2)
Vref
+25V
Vin
LM350
Vout R1Vout
620
Adjust
Iout
D2
1N4001
2N5640
R2
100
* To provide current limiting of IO
to the system ground, the source of
the FET must be tied to a negative
voltage below −1.25 V.
R2 ≤Vref
R1 = VSS*
D1
1N4001
VO < V(BR)DSS + 1.25 V + VSS
ILmin − IDSS < IO < 3.0 A
As shown O < IO < 1.0 A
Vin
D1
1N4002
Vout
120
Adjust
720
+
1.0mF
MPS2222
1.0k
TTL
Control
LM350
Minimum Vout = 1.25 V
D1 protects the device during an input short circuit.
+
10mF
Vin Vout
240 1N4001
LM350
Adjust
MPS2907
R2
50k
LM350
Vin Vout R1
Adjust IAdj
Iout
1.25 V
R1
^
10 mA ≤ Iout ≤ 3.0 A
IDSS
IOmax + IDSS
Iout +ǒVref
R1Ǔ)IAdj
LM350
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PACKAGE DIMENSIONS
TO−220, SINGLE GAUGE
T SUFFIX
CASE 221AB−01
ISSUE O
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION Z DEFINES A ZONE WHERE ALL
BODY AND LEAD IRREGULARITIES ARE
ALLOWED.
DIM MIN MAX MIN MAX
MILLIMETERSINCHES
A0.570 0.620 14.48 15.75
B0.380 0.405 9.66 10.28
C0.160 0.190 4.07 4.82
D0.025 0.035 0.64 0.88
F0.142 0.147 3.61 3.73
G0.095 0.105 2.42 2.66
H0.110 0.155 2.80 3.93
J0.018 0.025 0.46 0.64
K0.500 0.562 12.70 14.27
L0.045 0.060 1.15 1.52
N0.190 0.210 4.83 5.33
Q0.100 0.120 2.54 3.04
R0.080 0.110 2.04 2.79
S0.020 0.055 0.508 1.39
T0.235 0.255 5.97 6.47
U0.000 0.050 0.00 1.27
V0.045 −−− 1.15 −−−
Z−−− 0.080 −−− 2.04
B
Q
H
Z
L
V
G
N
A
K
F
123
4
D
SEATING
PLANE
−T−
C
S
T
U
R
J
LM350
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to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any
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LM350/D
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