Datasheet LM350K, LM250K, LM150K Datasheet (SGS Thomson Microelectronics)

Page 1
LM15 0/2 50
LM350
March1993
ADJUSTABLE VOLTAGE REGULATORS
THREE-TERMINAL 3 A
.GUARANTEED 3A OUTPUTCURRENT
.ADJUSTABLE OUTPUT DOWN TO 1.2V
.LINE REGULATIONTYPICALLY 0.005% /V
.GUARANTEED THERMAL REGULATION
.CURRENT LIMIT CONSTANT WITH TEM-
PERATURE
.STANDARD3-LEAD TRANSISTOR PACKAGE
TO3
K SUFFIX
(SteelCan)
ORDER CODE
PART
NUMBER
TEMPERATURE
RANGE
PACKAGE
K
LM150 LM250 LM350
-55
o
C to + 150oC
-25
o
C to + 150oC
0oC to + 125oC
EXAMPLE: LM150K
PIN CONNE CTI O N
(bottom view)
Case is output
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ABSOLUTE MAXIMUM RATING
Symbol Parameter Value Unit
P
tot
Power Dissipation Internally Limited W
V
I-VO
Input-Output Voltage DIfferential 35 V
T
oper
Operating Junction Temperature Range LM150
LM250 LM350
-55 to 150
-25 to 150 0 to 125
o
C
T
stg
Storage Temperature Range -65 to 150
o
C
T
lead
Lead Temperature (Soldering, 10 seconds) 300
o
C
THERMAL CHARACTERISTICS
Symbol Parameter Value Unit
R
th(j-c)
Typical Junction-Case Thermal Resistance 1.5
o
C/W
R
th(j-a)
Max Junction-Ambient Thermal Resistance 35
o
C/W
SCHEM ATIC DIA GRA M
LM150-LM250-LM350
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ELECTRICAL CHARACTERISTICS LM150: -55oC Tj≤ 150oC, VI-VO= 5V, IO= 1.5A LM250: -25oC Tj≤ 150oC, VI-VO= 5V, IO= 1.5A LM350: 0oC Tj≤ 150oC, VI-VO= 5V, IO= 1.5A
Although power dissipation is internally limited, these specifications apply to power dissipation up to 30W (unless otherwise specified).
Symbol Parameter LM150-LM250 LM350 Unit
Min. Typ. Max. Min. Typ. Max.
K
VI
Line Regulation - (note 1) T
amb
=25oC, 3 V (VI-VO)≤35 V
0.005 0.01 0.005 0.03 %/V
K
VO
Load Regulation T
amb
=25oC, 10 mA IO≤ 3A VO≤5V - (note 1) VO≥ 5V - (note 1)
5
0.1150.3
5
0.1250.5
mV
%
Thermal Regulation (pulse = 20 ms) 0.002 0.01 0.002 0.02 %/W
I
adj
Adjustment Pin Current 50 100 50 100 µA
I
adj
Adjustment Pin Current Change 10 mA IL≤ 3A,3V(VI-VO)35 V
0.2 5 0.2 5 µA
v
(ref)
Reference Voltage 3V (VI-VO)≤35 V, 10 mA IO≤ 3A, P ≤ 30W
1.19 1.24 1.29 1.19 1.24 1.29 V
K
VI
Line Regulation - (note 1) 3V(VI-VO)≤35 V
0.02 0.05 0.02 0.05 %/V
K
VO
Load Regulation 10 mA IO≤ 3A VO≤5V - (note 1) VO≥ 5V - (note 1)
20
0.3
50
1
20
0.3701.5
mV
%
K
VT
Temperature Stability (T
min
Tj≤ T
max
)11%
I
O(min)
Minimum Load Current (VI-VO≤35 V) 3.5 5 3.5 10 mA
I
O(max)
Current Limit (VI-VO≤10 V) DC V
I-VO
=30V
3 4.5
1
3 4.5
1
A
RMS Output Noise, % of V
O
(T
amb
=25oC, 10 Hz f 10 KHz)
0.001 0.001 %
R
vf
Ripple Rejection Ratio VO= 10 V, f = 120 Hz C
adi
=10µF66
65 86 66
65 86
dB
K
VH
Long Term Stability (T
amb
= 125oC) 0.3 1 0.3 1 %
Note 1 : Regulation is measured at constant junction temperature. Changes in output voltage due to heating effects are taken into account separately by thermal rejection.
LM150-LM250-LM350
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TYPICAL AP PLI CA TI O NS
+ 1.2V to + 25V ADJUSTABLE REGULATOR
APPLICATION HINTS
In operation,the LM350 develops anominal 1.25V reference voltage, V
(ref)
, between the output and adjustment terminal. The reference voltage is im­pressed across program resistor R1and, since the voltage is constant, aconstant current I1then flows through theoutput set resistor R2, giving an output voltage of
VO=V
(ref)
(1+
R
2
R
1
)+I
adjR2
Figure 1.
Since the 50µAcurrent from the adjustment termi­nal represents an error term, theLM350 was de­signed to minimize I
adj
and make it very constant withlineand load changes. To do this, allquiescent operating current is returned to the output establi­shing a minimum load currentrequirement. Ifthere is insufficientloadonthe output, the outputwill rise.
EXTERNAL CAPACITORS An input bypass capacitor is recommended. A
0.1µFdisc or1µFsolid tantalum on the inputis suit­able input by passing for almost all applications. Thedeviceismore sensitivetothe absenceofinput bypassing when adjustment or output capacitors are used byt the above values will eliminate the possibility of problems.
The adjustment terminal can be bypassed to ground on the LM350 to improve ripple rejection. This bypass capacitor prevents ripple form being amplified as the output voltage is increased. With a10µF bypass capacitor 75dB ripple rejection is obtainableatanyoutputlevel.Increases over20µF do not appreciably improve the ripple rejection at frequencies above 120Hz. If the bypass capacitor is used, it is sometimes necessary to include pro­tection diodes to prevent the capacitor from dis­charging through internal low current paths and damaging the device.
In general, the best type of capacitors to use are solid tantalum. Solid tantalumcapacitors have low impedance even at high frequencies. Depending upon capacitorconstruction, it takes about 25µFin aluminumelectrolyticto equal1µFsolid tantalum at high frequencies. Ceramic capacitors are also good at high frequencies, but some types have a large decrease in capacitance at frequencies around 0.5MHz. For this reason,0.01µF disc may seem towork better than a0.1µF discas a bypass.
Although the LM350 is stable with no output capa­citors, like any feedback circuit, certain values of external capacitancecan cause excessive ringing. This occurs with values between 500pF and 5000pF. A 1µF solid tantalum(or 25µF aluminium electrolytic) on the output swamps this effect and insures stability.
LOADREGULATION The LM350is capable ofproviding extremely good
load regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment termi­nal and the output terminal (usually 240Ω) should be tied directly tothe output of the regulator rather than near the load. This eliminates line drops from appearing effectively in series with the reference and degrading regulation. For example, a 15V regulator with 0.05resistance between theregu­lator and loadwill have a load regulationdue to line resistance of 0.05xIL. If the set resistor is con­nected near the load the effective line resistance
Needed if device is far from filter capacitors. *
Optional-improves transient response. Output capacitors in the range of 1µF to 100µF of aluminium or tantalum electrolytic are commonlyused toprovide improvedoutput impedance and rejec­tion of transients.
R2
** VO=1.25V(1+ )
R1
*** R1=240Ωfor LM150 and LM250
LM 350
LM 350
LM150-LM250-LM350
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Page 5
will be 0.05(1 + R2/R1)or in this case, 11.5times worse.
Figure 2showsthe effect of resistance between the regulator and 140set resistor.
Withthe TO-3package,itis easytominimizethere­sistance from the case to the set resistor, by using 2 separate leadsto the case. The ground of R2 can be returned near the ground of the load to provide remote ground sensing and improve load regula­tion.
PROTECTION DIODES WhenexternalcapacitorsareusedwithanyICregu-
lator it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. Most
Figure 2 : Regulator with LineResistance in Out-
put Lead.
20µF capacitors have lowenoughinternal seriesre­sistance to deliver 20A spikes when shorted. Al­thoughthe surgeis short,there is enough energy to damage parts of the IC.
When an output capacitor is connected to a regula­tor and theinput is shorted, the outputcapacitorwill discharge into the outputof the regulator. The dis­chargecurrentdepends on the value of thecapaci­tor, theoutputvoltage ofthe regulator, and therate of decrease of VI. Inthe LM350 this discharge path is through alarge junctionthatisable to sustain25A surgewithno problem.Thisis nottrue ofother types of positive regulators. For output capacitors of 100µF or less at output of 15V or less, there is no need to use diodes.
The bypass capacitor on the adjustment terminal can discharge through a low current junction. Dis­charge occurs when either the input or output is shorted. Internal to the LM350 is a 50resistor which limits the peakdischargecurrent. No protec­tionis neededforoutputvoltages of 25V or less and 10µF capacitance. Figure 3 shows an LM350 with protection diodes included for use with outputs greaterthan 25Vand high valuesof output capacit­ance.
Figure 3 : Regulator with Protection Diodes.
LM350
LM350
LM150-LM250-LM350
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DIM.
mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A 11.00 13.10 0.433 0.516
B 0.97 1.15 0.038 0.045
C 1.50 1.65 0.059 0.065
D 8.32 8.92 0.327 0.351
E 19.00 20.00 0.748 0.787
G 10.70 11.10 0.421 0.437
N 16.50 17.20 0.649 0.677
P 25.00 26.00 0.984 1.023
R 4.00 4.09 0.157 0.161
U 38.50 39.30 1.515 1.547
V 30.00 30.30 1.187 1.193
C
D
N
B
V
U
R
A
P
E
G
O
P003F
TO-3 MECHANICAL DATA
LM150-LM250-LM350
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Information furnished is believed to be accurate and reliable.However, SGS-THOMSON Microelectronics assumes no responsability for the consequences of useof such information nor for any infringementof patents or other rights of third parties which may results from its use. No license isgranted by implication or otherwise underany patent or patent rights ofSGS-THOMSON Microelectronics. Specificationsmentioned in this publication are subject to changewithout notice.This publication supersedes andreplaces all information previously supplied. SGS-THOMSON Microelectronicsproductsare not authorized foruse ascritical componentsinlife supportdevices orsystems without express written approval of SGS-THOMSON Microelectonics.
1994 SGS-THOMSON Microelectronics- All RightsReserved
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LM150-LM250-LM350
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