ETC LM350BT

ON Semiconductor
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.
• 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
LM350
THREE–TERMINAL
ADJUSTABLE POSITIVE
VOLTAGE REGULATOR
SEMICONDUCTOR
TECHNICAL DATA
T SUFFIX
PLASTIC PACKAGE
CASE 221A
Pin 1. Adjust
2. Vout
3. Vin
1
2
3
Heatsink surface is connected to Pin 2.
ORDERING INFORMATION
Simplified Application
Device
Vin
vout
LM350
IAdj
Cin*
0.1µF
LM350T
LM350BT#
R1
240
Adjust
Operating
Temperature Range
Package
TJ = 0° to +125°C
Plastic Power
TJ = –40° to +125°C
Plastic Power
# Automotive temperature range selections are
available with special test conditions and additional
tests. Contact your local ON Semiconductor sales
office for information.
+ C **
O
1µF
R2
* = 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.
R
Vout 1.25V
1 2 IAdjR2
R1
Since IAdj is controlled to less than 100 µA, the error associated with
this term is negligible in most applications.
 Semiconductor Components Industries, LLC, 2002
January, 2002 – Rev. 2
1
Publication Order Number:
LM350/D
LM350
MAXIMUM RATINGS
Rating
Symbol
Value
Unit
VI–VO
35
Vdc
Power Dissipation
PD
Internally Limited
W
Operating Junction Temperature Range
TJ
–40 to +125
°C
Storage Temperature Range
Tstg
–65 to +150
°C
Tsolder
300
°C
Input–Output Voltage Differential
Soldering Lead Temperature (10 seconds)
ELECTRICAL CHARACTERISTICS (VI–VO = 5.0 V; IL = 1.5 A; TJ = Tlow to Thigh; Pmax [Note 1], unless otherwise noted.)
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
Regtherm
–
0.002
–
% VO/W
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
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
–
–
–
0.003
–
–
66
65
80
–
–
–
0.3
1.0
–
–
2.3
–
–
1.5
Characteristics
Thermal Regulation, Pulse = 20 ms,
(TA = +25°C)
Adjustment Pin Current
RMS Noise, % of VO
TA= 25°C, 10 Hz ≤ f ≤ 10 kHz
N
Ripple Rejection, VO = 10 V, f = 120 Hz (Note 3)
Without CAdj
CAdj = 10 µF
4
Long Term Stability, TJ = Thigh (Note 4)
TA= 25°C for Endpoint Measurements
3
Thermal Resistance, Junction–to–Case
Peak (Note 5)
Average (Note 6)
A
RR
S
% VO
dB
%/1.0 k
Hrs.
°C/W
RθJC
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).
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LM350
Representative Schematic Diagram
310
310
230
Vin
5.6K
120
6.3V
510
12.4K
30
pF
5.1K
110
5.8K
3.6K
30
pF
190
160
12K
5.0pF
6.8K
6.3V
135
125K
6.7K
170
13K
200
6.3V
2.4K
105
12.5K
4
0.45
Vout
Adjust
VCC
Line Regulation (%/V) =
*
VIH
VIL
Vin
Vout
LM350
Adjust
Cin
*Pulse Testing Required:
1% Duty Cycleis suggested.
0.1µF
IL
R1
240
1%
R2
1%
Figure 1. Line Regulation and ∆IAdj/Line Test Circuit
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x 100
VOH
VOL
CO
IAdj
VOH - VOL
VOL
+
RL
1µF
LM350
Load Regulation (% VO) =
VO (min Load) - VO (max Load)
VO (min Load)
X 100
Load Regulation (mV) = VO (min Load) -VO (max Load)
Vin
Vin
Vout
LM350
IL
Adjust
Cin
0.1µF
VO (min Load)
VO (max Load)
RL
(max Load)
240
1%
R1
+
CO
IAdj
*
RL
(min Load)
1.0µF
R2
1%
*Pulse Testing Required:
1% Duty Cycle is suggested.
Figure 2. Load Regulation and ∆IAdj/Load Test Circuit
Vin
Vout
LM350
IL
Adjust
VI
Cin
IAdj
0.1µF
240
1%
R1
Vref
RL
+
CO
1.0µF
VO
ISET
R2
1%
To Calculate R2:
Vout = ISET R2 + 1.250 V
Assume ISET = 5.25 mA
Pulse Testing Required:
1% Duty Cycle is suggested.
Figure 3. Standard Test Circuit
24V
14V
Vin
f = 120 Hz
LM350
Vout
Adjust
Cin
Vout = 10 V
IL
240
1%
R1
0.1µF
D1 *
1N4002
CO
R2
**
CAdj
1.65K
1%
+
+
RL
1.0µF
10µF
*D1 Discharges CAdj if Output is Shorted to Ground.
**CAdj provides an AC ground to the adjust pin.
Figure 4. Ripple Rejection Test Circuit
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VO
7
0.4
I out , OUTPUT CURRENT (A)
∆ Vout , OUTPUT VOLTAGE CHANGE (%)
LM350
0.2
0
IL = 0.5 A
-0.2
IL = 1.5 A
-0.4
-0.6
Vin = 15 V
Vout = 10 V
-0.8
-1.0
-75
-50
-25
0
25
50
75
100 125
TJ, JUNCTION TEMPERATURE (°C)
TJ = 55°C
5
TJ = 25°C
3
TJ = 150°C
1
0
150
0
10
20
30
Vin-Vout, INPUT VOLTAGE DIFFERENTIAL (Vdc)
Figure 6. Current Limit
3.0
V in -Vout , INPUT-OUTPUT VOLTAGE
DIFFERENTIAL (Vdc)
IAdj, ADJUSTMENT PIN CURRENT (µA)
Figure 5. Load Regulation
70
65
60
55
50
45
40
35
-75
-50
-25
0
25
50
75 100 125
TJ, JUNCTION TEMPERATURE (°C)
IL = 3.0 A
IL = 2.0 A
2.0
IL = 500 mA
1.5
1.0
-75
150
∆V0 = 100 mV
2.5
Figure 7. Adjustment Pin Current
IL = 200 mA
IL = 20 mA
-50
-25
0
25
50
75 100 125
TJ, JUNCTION TEMPERATURE (°C)
150
Figure 8. Dropout Voltage
1.260
5.0
IB , QUIESCENT CURRENT (mA)
Vref , REFERENCE VOLTAGE (V)
40
1.250
1.240
1.230
4.5
TJ = -55°C
4.0
TJ = 25°C
3.5
3.0
TJ = 150°C
2.5
2.0
1.5
1.0
0.5
1.220
-75
-50
-25
0
25
50
75 100 125
TJ, JUNCTION TEMPERATURE (°C)
0
150
0
Figure 9. Temperature Stability
10
20
30
40
Vin-Vout, INPUT-OUTPUT VOLTAGE DIFFERENTIAL (Vdc)
Figure 10. Minimum Operating Current
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LM350
100
140
RR, RIPPLE REJECTION (dB)
RR, RIPPLE REJECTION (dB)
CAdj = 10 µF
80
Without CAdj
60
40
Vin - Vout = 5 V
IL = 500 mA
f = 120 Hz
TJ = 25°C
20
0
0
5
10
15
20
25
30
Vout, OUTPUT VOLTAGE (V)
120
100
60
40
20
0
0.01
35
Figure 11. Ripple Rejection versus Output Voltage
0.1
1
Iout, OUTPUT CURRENT (A)
IL = 500 mA
Vin = 15 V
Vout = 10 V
TJ = 25°C
80
60
40
CAdj = 10 µF
Without CAdj
20
100
1.0 k
10 k
100 k 1.0 M
f, FREQUENCY (Hz)
100
10-1
Without CAdj
10-2
10-3
10 M
Vin = 15 V
Vout = 10 V
IL = 500 mA
TJ = 25°C
CAdj = 10 µF
10
100
∆ Vout , OUTPUT VOLTAGE
DEVIATION (V)
1.5
1.0
CL = 1.0 µF; CAdj = 10 µF
0.5
1.0 k
10 k
f, FREQUENCY (Hz)
100 k
0
3
2
1
CL = 1.0 µF; CAdj = 10 µF
0
Vin = 15 V
Vout = 10 V
INL = 50 mA
TJ = 25°C
-1
-0.5
-2
Vout = 10 V
IL = 50 mA
TJ = 25°C
-1.0
-1.5
1.0
1.5
CL = 0; Without CAdj
1.0
Vin
0
10
CL = 0; Without CAdj
-3
0.5
20
IL
0.5
30
1.0 M
Figure 14. Output Impedance
I L , LOAD
CURRENT (A)
∆ Vin , INPUT VOLTAGE
CHANGE (V)
∆ Vout , OUTPUT VOLTAGE
DEVIATION (V)
Figure 13. Ripple Rejection versus Frequency
0
10
101
Z O , OUTPUT IMPEDANCE (
Ω)
RR, RIPPLE REJECTION (dB)
Without CAdj
Vin - Vout = 5 V
IL = 500 mA
f = 120 Hz
TJ = 25°C
Figure 12. Ripple Rejection versus Output Current
100
0
10
CAdj = 10 µF
80
40
0
t, TIME (µs)
20
t, TIME (µs)
Figure 15. Line Transient Response
Figure 16. Load Transient Response
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0
10
30
40
LM350
APPLICATIONS INFORMATION
Basic Circuit Operation
External Capacitors
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:
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.
Vout = Vref (1 +
R2
) + 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.
Vin
LM350
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.
Vout
+
Vref
Adjust
Protection Diodes
R1
IPROG
Vout
IAdj
R2
D1
Vref = 1.25 V Typical
1N4002
Vin
Figure 17. Basic Circuit Configuration
Load Regulation
LM350
Cin
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.
Vout
R1
+
D2
Adjust
1N4002
R2
CAdj
Figure 18. Voltage Regulator with
Protection Diodes
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CO
LM350
D6
1N4002
Vin
32V
Vout1 RSC
LM350
(1)
Vin1
Vin2
IO
Vout 2
LM350
(2)
VO
240
0.1µF
D1
1N4001
Adjust 1
1K
Current
Limit
Adjust
Adjust 2
1N4001
D2
5.0K
Q1
2N3822
+
D5
IN4001
+
1.0µF
Tantalum
10µF
Voltage
Adjust
1N4001
D3
D4
-10V
Q2
2N5640
Diodes D1 and D2 and transistor Q2 are added to allow adjustment
of output voltage to 0 V.
Output Range:
0 ≤ VO ≤ 25 V
0 ≤ IO ≤ 1.5 A
1N4001
-10V
D6 protects both LM350's during an input short circuit.
Figure 19. “Laboratory” Power Supply with Adjustable Current Limit and Output Voltage
+25V
Vout
LM350
Vin
Vout
R1
Iout
620
Adjust
D1
D1
1N4001
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.
Vref
R2 ≤
IDSS
Vref
R1 =
IOmax + IDSS
Vin
D2
1N4001
Adjust
2N5640
1.0µF
1.0k
VSS*
TTL
Control
Minimum Vout = 1.25 V
D1 protects the device during an input short circuit.
Figure 21. 5.0 V Electronic Shutdown Regulator
Vin
Vout
240
Adjust
1N4001
50k
MPS2907
Vout
LM350
Adjust
R2
+
MPS2222
720
Figure 20. Adjustable Current Limiter
LM350
Vout
LM350
120
VO < V(BR)DSS + 1.25 V + VSS
ILmin - IDSS < IO < 3.0 A
As shown O < IO < 1.0 A
Vin
1N4002
IAdj
Iout +
10µF
R1
VRref1 IAdj
1.25 V
R1
10 mA ≤ Iout ≤ 3.0 A
Figure 22. Slow Turn–On Regulator
Figure 23. Current Regulator
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Iout
LM350
PACKAGE DIMENSIONS
T SUFFIX
PLASTIC PACKAGE
CASE 221A–09
ISSUE AA
–T–
B
SEATING
PLANE
C
F
T
S
4
DIM
A
B
C
D
F
G
H
J
K
L
N
Q
R
S
T
U
V
Z
A
Q
1 2 3
U
H
K
Z
L
R
V
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.
J
G
D
N
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INCHES
MIN
MAX
0.570
0.620
0.380
0.405
0.160
0.190
0.025
0.035
0.142
0.147
0.095
0.105
0.110
0.155
0.018
0.025
0.500
0.562
0.045
0.060
0.190
0.210
0.100
0.120
0.080
0.110
0.045
0.055
0.235
0.255
0.000
0.050
0.045
----0.080
MILLIMETERS
MIN
MAX
14.48
15.75
9.66
10.28
4.07
4.82
0.64
0.88
3.61
3.73
2.42
2.66
2.80
3.93
0.46
0.64
12.70
14.27
1.15
1.52
4.83
5.33
2.54
3.04
2.04
2.79
1.15
1.39
5.97
6.47
0.00
1.27
1.15
----2.04
LM350
Notes
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LM350
Notes
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LM350
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LM350/D