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LM150/250 LM350
THREE-TERMINAL 3 A ADJUSTABLE VOLTAGE REGULATORS
.GUARANTEED3AOUTPUTCURRENT .ADJUSTABLEOUTPUTDOWNTO1. .LI .LOADREGULATI .GUARANTEEDTHERMALREGULATI .CURRENT .STANDARD3-
2V NE REGULATION TYPICALLY 0.005% /V ON TYPICALLY 0.1% ON LIMIT CONSTANT WITH TEMPERATURE LEAD TRANSISTOR PACKAGE
TO3 K SUFFIX (Steel Can)
ORDER CODE
PART NUMBER TEMPERATURE RANGE PACKAGE K * * *
LM150 -55 oC to + 150 oC LM250 -25 oC to + 150 oC LM350 0 oC to + 125 oC EXAMPLE: LM150K
PIN CONNECTION (bottom view)
Case is output
March 1993
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LM150-LM250-LM350
ABSOLUTE MAXIMUM RATING
Symbol Ptot V I - VO Toper Power Dissipation Input-Output Voltage DIfferential Operating Junction Temperature Range LM150 LM250 LM350 Parameter Value Internally Limited 35 -55 to 150 -25 to 150 0 to 125 -65 to 150 300 Unit W
o
V C
Tstg Tlead
Storage Temperature Range Lead Temperature (Soldering, 10 seconds)
o o
C C
THERMAL CHARACTERISTICS
Symbol Parameter Rth(j-c) Typical Junction-Case Thermal Resistance Rth(j-a) Max Junction-Ambient Thermal Resistance Value 1.5 35
o o
Unit C/W C/W
SCHEMATIC DIAGRAM
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LM150-LM250-LM350
ELECTRICAL CHARACTERISTICS LM150: -55 oC T j 150 oC, VI - VO = 5V, IO = 1.5A LM250: -25 oC T j 150 oC, VI - VO = 5V, IO = 1.5A LM350: 0 oC T j 150 oC, VI - VO = 5V, I O = 1.5A Although power dissipation is internally limited, these specifications apply to power dissipation up to 30W (unless otherwise specified).
Symbol K VI K VO Parameter Line Regulation - (note 1) Tamb = 25 oC, 3 V (V I - VO) 35 V Load Regulation Tamb = 25 oC, 10 mA IO 3 A VO 5V - (note 1) VO 5V - (note 1) Thermal Regulation (pulse = 20 ms) Adjustment Pin Current Adjustment Pin Current Change 10 mA IL 3 A, 3 V (VI - VO) 35 V Reference Voltage 3V (VI - VO) 35 V, 10 mA IO 3A, P 30W Line Regulation - (note 1) 3 V (V I - VO) 35 V Load Regulation 10 mA IO 3 A VO 5V - (note 1) VO 5V - (note 1) Temperature Stability (Tmin Tj Tmax) Minimum Load Current (VI - VO 35 V) Current Limit (VI - VO 10 V) DC VI - VO = 30 V RMS Output Noise, % of VO (Tamb = 25 oC, 10 Hz f 10 KHz) Ripple Rejection Ratio VO = 10 V, f = 120 Hz Cadi = 10 F Long Term Stability (Tamb = 125 oC) LM150-LM250 Min. Typ. Max. 0.005 0.01 Min. LM350 Typ. 0.005 Unit Max. 0.03 %/V
Iadj Iadj v(ref) K VI K VO
5 0.1 0.002 50 0.2 1.19 1.24 0.02
15 0.3 0.01 100 5 1.29 0.05 1.19
5 0.1 0.002 50 0.2 1.24 0.02
25 0.5 0.02 100 5 1.29 0.05
mV % %/W A A V %/V
KVT IO(min) IO(max)
20 0.3 1 3.5 3 4.5 1 0.001
50 1 5 3
20 0.3 1 3.5 4.5 1 0.001
70 1.5 10
mV % % mA A
% dB
Rvf
66
KVH
65 86 0.3
66 1
65 86 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.
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LM150-LM250-LM350
TYPICAL APPLICATIONS + 1.2V to + 25V ADJUSTABLE REGULATOR
LM350
Since the 50A current from the adjustment terminal represents an error term, the LM350 was designed to minimize Iadj and make it very constant with line and load changes. To do this, all quiescent operating current is returned to the output establishing a minimum load current requirement. If there is insufficient load on the output, the output will rise. EXTERNAL CAPACITORS An input bypass capacitor is recommended. A 0.1F disc or 1F solid tantalum on the input is suitable input by passing for almost all applications. The device is more sensitive to the absence of input 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 a 10F bypass capacitor 75dB ripple rejection is obtainable at any output level. Increases over 20F 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 tantalum capacitors have low impedance even at high frequencies. Depending upon capacitor construction, it takes about 25F in aluminum electrolytic to equal 1F solid 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, 0.01F disc may seem to work better than a 0.1F disc as a bypass. Although the LM350 is stable with no output capacitors, like any feedback circuit, certain values of external capacitance can cause excessive ringing. This occurs with values between 500pF and 5000pF. A 1F solid tantalum (or 25F aluminium electrolytic) on the output swamps this effect and insures stability. LOAD REGULATION The LM350 is capable of providing 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 240) should be tied directly to the 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 0.05 resistance between the regulator and load will have a load regulation due to line resistance of 0.05 x IL. 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 1F to 100F of aluminium or tantalum electrolytic are commonly used to provide improved output impedance and rejection of transients. R2 * * VO = 1.25V (1 + ) R1 * * * R1 = 240 for LM150 and LM250
APPLICATION HINTS In operation, the LM350 develops a nominal 1.25V reference voltage, V(ref), between the output and adjustment terminal. The reference voltage is impressed across program resistor R1 and, since the voltage is constant, a constant current I1 then flows through the output set resistor R2, giving an output voltage of R2 VO = V(ref) ( 1+ ) + IadjR2 R1 Figure 1.
LM350
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LM150-LM250-LM350
will be 0.05 (1 + R2/R1) or in this case, 11.5 times worse. Figure 2 shows the effect of resistance between the regulator and 140 set resistor. With the TO-3 package, it is easy to minimize the resistance from the case to the set resistor, by using 2 separate leads to 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 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. Most Figure 2 : Regulator with Line Resistance in Output Lead.
LM350
20F capacitors have low enough internal series resistance to deliver 20A spikes when shorted. Although the surge is short, there is enough energy to damage parts of the IC. When an output capacitor is connected to a regulator and the input is shorted, the output capacitor will discharge into the output of the regulator. The discharge current depends on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of VI. In the LM350 this discharge path is through a large junction that is able to sustain 25A surge with no problem. This is not true of other types of positive regulators. For output capacitors of 100F 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 50 resistor which limits the peak discharge current. No protection is needed for output voltages of 25V or less and 10F capacitance. Figure 3 shows an LM350 with protection diodes included for use with outputs greater than 25V and high values of output capacitance.
Figure 3 : Regulator with Protection Diodes.
LM350
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LM150-LM250-LM350
TO-3 MECHANICAL DATA
mm MIN. A B C D E G N P R U V 11.00 0.97 1.50 8.32 19.00 10.70 16.50 25.00 4.00 38.50 30.00 TYP. MAX. 13.10 1.15 1.65 8.92 20.00 11.10 17.20 26.00 4.09 39.30 30.30 MIN. 0.433 0.038 0.059 0.327 0.748 0.421 0.649 0.984 0.157 1.515 1.187 inch TYP. MAX. 0.516 0.045 0.065 0.351 0.787 0.437 0.677 1.023 0.161 1.547 1.193
DIM.
P G
A
D
C
U
V
O
N
R
B
P003F
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E
LM150-LM250-LM350
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsability for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may results from its use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use ascritical components in life support devices or systems without express written approval of SGS-THOMSON Microelectonics. (c) 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A
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