SEMICONDUCTOR
TECHNICAL DATA
THREE–TERMINAL
ADJUSTABLE POSITIVE
VOLTAGE REGULATOR
ORDERING INFORMATION
Order this document by LM350/D
T SUFFIX
PLASTIC PACKAGE
CASE 221A
Pin 1. Adjust
2. Vout
3. Vin
Heatsink surface is connected to Pin 2.
123
Device Operating
Temperature Range Package
LM350T
LM350BT# Plastic Power
Plastic PowerTJ = 0° to +125°C
TJ = –40° to +125°C
# Automotive temperature range selections are
available with special test conditions and additional
tests. Contact your local Motorola sales office for
information.
1
MOTOROLA ANALOG IC DEVICE DATA
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.
•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
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.
Since IAdj is controlled to less than 100
µ
A, the error associated with
this term is negligible in most applications.
LM350
Vin vout
R1
240
R2
Adjust
IAdj
Cin*
0.1
µ
F+CO**
1
µ
F
Vout
+
1.25 V
ǒ
1
)
R2
R1
Ǔ)
IAdj R2
Motorola, Inc. 1996 Rev 0
LM350
2MOTOROLA ANALOG IC DEVICE DATA
MAXIMUM RATINGS
Rating Symbol Value Unit
Input–Output Voltage Differential 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
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 1Regline –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 µA
Adjustment Pin Current Change
3.0 V ≤ VI–VO ≤ 35 V
10 mA ≤ IL ≤ 3.0 A, PD ≤ Pmax
1,2 ∆IAdj –0.2 5.0 µA
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 1Regline –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 µF
4RR –
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)
RθJC –
–2.3
––
1.5
°C/W
NOTES: 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
3
MOTOROLA ANALOG IC DEVICE DATA
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
VIHVIL Vin Vout VOH
VOL
RL
+1
µ
FCO
240
1%
R1
Adjust
R2
1%
Cin 0.1
µ
F
LM350
IAdj
IL
Figure 1. Line Regulation and ∆IAdj/Line Test Circuit
VOL
LM350
4MOTOROLA ANALOG IC DEVICE DATA
* 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 0.1
µ
F
Adjust
R2
1%
CO1.0
µ
F
+*
RL
(max Load) RL
(min Load)
Vout
R1240
1%
Vin Vin
IAdj
IL
Figure 2. Load Regulation and ∆IAdj/Load Test Circuit
VO (min Load)
Pulse Testing Required:
1% Duty Cycle is suggested.
LM350
Vin Vout
Adjust R1240
1% +1.0
µ
FCO
RL
Cin
R2
1%
To Calculate R2:
Vout = ISET R2 + 1.250 V
Assume ISET = 5.25 mA
IL
IAdj
ISET
Vref
VO
VI
0.1
µ
F
Figure 3. Standard Test Circuit
LM350
Vin Vout Vout = 10 V
RL
Cin 0.1
µ
F
Adjust R1240
1%
D1 *
1N4002
CO+1.0
µ
F
24V
14V
R21.65K
1% CAdj 10
µ
F
+
*D
1
Discharges CAdj if Output is Shorted to Ground.
**CAdj provides an AC ground to the adjust pin.
f = 120 Hz
VO
IL
**
Figure 4. Ripple Rejection Test Circuit
LM350
5
MOTOROLA ANALOG IC DEVICE DATA
ref
V , REFERENCE VOLTAGE (V)
IB, QUIESCENT CURRENT (mA)
IAdj, ADJUSTMENT PIN CURRENT ( A)
µ
Vout, OUTPUT VOLTAGE CHANGE (%)
∆
Figure 5. Load Regulation Figure 6. Current Limit
Figure 7. Adjustment Pin Current Figure 8. Dropout Voltage
Figure 9. Temperature Stability Figure 10. 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
V
in–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
∆
V0 = 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
0010203040
V
in–Vout, INPUT–OUTPUT VOL TAGE DIFFERENTIAL (Vdc)
TJ = –55
°
C
TJ = 25
°
C
TJ = 150
°
C
TJ = 55
°
C
TJ = 150
°
C
TJ = 25
°
C
Vin–Vout, INPUT–OUTPUT VOLT AGE
DIFFERENTIAL (Vdc)
LM350
6MOTOROLA ANALOG IC DEVICE DATA
Vout, OUTPUT VOLTAGE
∆
DEVIATION (V)
ZO
Ω
, OUTPUT IMPEDANCE ( )
Vout, OUTPUT VOLTAGE
∆
DEVIATION (V)
Vin, INPUT VOLTAGE
∆
CHANGE (V)
Figure 11. Ripple Rejection versus Output Voltage Figure 12. Ripple Rejection versus Output Current
Figure 13. Ripple Rejection versus Frequency Figure 14. Output Impedance
Figure 15. Line Transient Response Figure 16. Load Transient Response
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
1.0
0.5
00 10203040
t, TIME (
µ
s)
CL = 1.0
µ
F; CAdj = 10
µ
F
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 (
µ
s)
I
CURRENT (A)
L, LOAD
CL = 0; Without CAdj
CL = 1.0
µ
F; CAdj = 10
µ
F
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
µ
F120
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
µ
F
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
µ
F
Vin = 15 V
Vout = 10 V
IL = 500 mA
TJ = 25
°
C
CAdj = 10
µ
F
Without CAdj
101
100
10–1
10–2
10–310 100 1.0 k 10 k 100 k 1.0 M
f, FREQUENCY (Hz)
140
LM350
7
MOTOROLA ANALOG IC DEVICE DATA
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 17), 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 µA 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
IPROGVout
R2
IAdj
Vref = 1.25 V Typical
Figure 17. 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 µF disc or 1 µF 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 µF 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 µF tantalum or 25 µF
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 µF, CAdj > 10 µF). 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 18. Voltage Regulator with
Protection Diodes
LM350
8MOTOROLA ANALOG IC DEVICE DATA
Figure 19. “Laboratory” Power Supply with Adjustable Current Limit and Output Voltage
Figure 20. Adjustable Current Limiter Figure 21. 5.0 V Electronic Shutdown Regulator
Figure 22. Slow Turn–On Regulator Figure 23. Current Regulator
D6
1N4002
Vin
32V Vin1
LM350
(1)
Adjust 1
Vout1 RSC Vin2 Vout 2IOVO
IN4001
1N4001
240 D5
1N4001
+1.0
µ
F
Tantalum
1K
Current
Limit
Adjust Q1
2N3822
5.0K Adjust 2
Voltage
Adjust
+10
µ
F
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
0.1
µ
F
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
+1.0
µ
F
MPS2222
1.0k TTL
Control
LM350
Minimum Vout = 1.25 V
D1 protects the device during an input short circuit.
+10
µ
F
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
+ǒ
Vref
R1
Ǔ)
IAdj
LM350
9
MOTOROLA ANALOG IC DEVICE DATA
OUTLINE DIMENSIONS
T SUFFIX
PLASTIC PACKAGE
CASE 221A–06
ISSUE Y
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
S0.045 0.055 1.15 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
10 MOTOROLA ANALOG IC DEVICE DATA
NOTES
LM350
11
MOTOROLA ANALOG IC DEVICE DATA
NOTES
LM350
12 MOTOROLA ANALOG IC DEVICE DATA
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding
the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and
specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola
data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals”
must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of
others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other
applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury
or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola
and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees
arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola
was negligent regarding the design or manufacture of the part. Motorola and are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal
Opportunity/Af firmative Action Employer .
How to reach us:
USA/EUROPE/Locations Not Listed: Motorola Literature Distribution; JAPAN: Nippon Motorola Ltd.; Tatsumi–SPD–JLDC, 6F Seibu–Butsuryu–Center,
P.O. Box 20912; Phoenix, Arizona 85036. 1–800–441–2447 or 602–303–5454 3–14–2 Tatsumi Koto–Ku, Tokyo 135, Japan. 03–81–3521–8315
MFAX: RMF AX0@email.sps.mot.com – TOUCHT ONE 602–244–6609 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park,
INTERNET: http://Design–NET.com 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852–26629298
LM350/D
*LM350/D*
◊
