Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - LDO voltage regulator Negative, adjustable TO 220 3

137afb

LT137A/LM137

LT337A/LM337

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Negative Adjustable

Regulator

The LT

137A/LT337A negative adjustable regulators will

deliver up to 1.5A output current over an output voltage

range of –1.2V to –37V. Linear Technology has made

signiﬁ cant improvements in these regulators compared to

previous devices, such as better line and load regulation,

and a maximum output voltage error of 1%.

Every effort has been made to make these devices easy

to use and difﬁ cult to damage. Internal current and power

limiting coupled with true thermal limiting prevents device

damage due to overloads or shorts, even if the regulator

is not fastened to a heat sink.

Maximum reliability is attained with Linear Technology’s

advanced processing techniques combined with a 100%

burn-in in the thermal limit mode. This assures that all

device protection circuits are working and eliminates ﬁ eld

failures experienced with other regulators that receive only

standard electrical testing.

Negative Regulator

Guaranteed 1% Initial Voltage Tolerance

Guaranteed 0.01%/V Line Regulation

Guaranteed 0.5% Load Regulation

Guaranteed 0.02%/W Thermal Regulation

100% Burn-in in Thermal Limit

Adjustable Power Supplies

System Power Supplies

Precision Voltage/Current Regulators

On-Card Regulators

L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners.

Output Voltage Error

LT137A

ADJ

–V

R2*

*R2 = R1

OUT

–V

OUT

= 1.25V 1 +

137A TA01

121Ω

1μF

SOLID

TANTALUM

5μF

SOLID

TANTALUM



– 1

OUT

1.25V



OUTPUT VOLTAGE (V)

12 468 2040

OUTPUT VOLTAGE ERROR (%)

10 100

137A TA01b

LM337

LT337A

1% RESISTORS

2% RESISTORS

Summary of content (12 pages)

PAGE 1
LT137A/LM137 LT337A/LM337 Negative Adjustable Regulator FEATURES DESCRIPTION n The LT®137A/LT337A negative adjustable regulators will deliver up to 1.5A output current over an output voltage range of –1.2V to –37V. Linear Technology has made signiﬁcant improvements in these regulators compared to previous devices, such as better line and load regulation, and a maximum output voltage error of 1%. n n n n Guaranteed 1% Initial Voltage Tolerance Guaranteed 0.01%/V Line Regulation Guaranteed 0.
PAGE 2
LT137A/LM137 LT337A/LM337 ABSOLUTE MAXIMUM RATINGS (Note 1) Power Dissipation .......................…….Internally Limited Input to Output Voltage Differential ..................…….40V Operating Junction Temperature Range LT137A/LM137 .................................. –55°C to 150°C LT337A/LM337 ...................................... 0°C to 125°C Storage Temperature Range LT137A/LM137 .................................. –65°C to 150°C LT337A/LM337 ..................................
PAGE 3
LT137A/LM137 LT337A/LM337 ORDER INFORMATION LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LM337T LM337T#TR LM337T 3-Lead Plastic TO-220 0°C to 125°C Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based ﬁnish parts. For more information on lead free part marking, go to: http://www.linear.
PAGE 4
LT137A/LM137 LT337A/LM337 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Notes 2, 3) LT337A SYMBOL PARAMETER VREF Reference Voltage CONDITIONS MIN |VIN – VOUT| = 5V, IOUT = 10mA, Tj = 25°C 3V ≤ |VIN – VOUT| ≤ 40V TYP LM337 MAX MIN TYP MAX –1.238 –1.250 –1.262 –1.213 –1.250 –1.287 l –1.220 –1.250 –1.280 –1.200 –1.250 –1.
PAGE 5
LT137A/LM137 LT337A/LM337 TYPICAL PERFORMANCE CHARACTERISTICS Dropout Voltage Temperature Stability 3.0 Minimum Load Current 1.270 1.8 Tj = 25°C 1.8 Tj = 150°C 1.4 Tj = –55°C 1.4 1.260 CURRENT (mA) Tj = –55°C 2.2 REFERENCE VOLTAGE (V) INPUT-OUTPUT DIFFERENTIAL 1.6 2.6 1.250 1.240 1.2 1.0 Tj = 25°C 0.8 0.6 Tj = 150°C 0.4 0.2 1.0 0.4 0.8 1.2 1.6 OUTPUT CURRENT (A) 2.0 1.
PAGE 6
LT137A/LM137 LT337A/LM337 TYPICAL PERFORMANCE CHARACTERISTICS Output Impedance Line Transient Response CADJ = 0 Load Transient Response 0.6 0.6 0.4 0.4 OUTPUT VOLTAGE DEVIATION (V) 0.8 CADJ = 0 0.2 0 CADJ = 10μF –0.2 CADJ = 10μF 10–3 10 100 1k 10k FREQUENCY (Hz) 100k 1M VOUT = –10V IL = 50mA CL = 1μF Tj = 25°C 0 –0.5 –1.0 0 10 20 TIME (μs) 30 137A G07 –0.4 40 –1.0 –1.5 0 OUTPUT CURRENT (A) –0.
PAGE 7
LT137A/LM137 LT337A/LM337 APPLICATIONS INFORMATION Output Voltage EXAMPLES: The output voltage is determined by two external resistors, R1 and R2 (see Figure 1). The exact formula for the output voltage is: 1. A precision 10V regulator to supply up to 1A load current. ⎛ R2 ⎞ VOUT = VREF ⎜ 1+ ⎟ + IADJ (R2) ⎝ R1⎠ b. Calculate R2 = Where: VREF = Reference Voltage, IADJ = Adjustment Pin Current. In most applications, the second term is small enough to be ignored, typically about 0.5% of VOUT.
PAGE 8
LT137A/LM137 LT337A/LM337 APPLICATIONS INFORMATION becomes shorted, due to the output capacitor discharging into the regulator. This can be prevented by using the diode D1 (see Figure 2) between the input and the output. The input capacitor, C2, is only required if the regulator is more than 4 inches from the raw supply ﬁlter capacitor. Bypassing the Adjustment Pin The adjustment pin of the LT137A may be bypassed with a capacitor to ground, C1, to reduce output ripple, noise, and impedance.
PAGE 9
LT137A/LM137 LT337A/LM337 TYPICAL APPLICATIONS A high stability regulator is illustrated in the application circuit shown to the right. The output stability, load regulation, line regulation, thermal regulation, temperature drift, long term drift, and noise can be improved by a factor of 6.6 over the standard regulator conﬁguration. This assumes a zener whose drift and noise is considerably better than the regulator itself.
PAGE 10
LT137A/LM137 LT337A/LM337 SCHEMATIC DIAGRAM ADJ 2k Q1 Q2 2k D4 Q3 20k Q4 15pF Q5 D1 Q6 D2 D3 750Ω 100k 600Ω 800Ω Q32 Q34 60k Q7 VOUT 5k 15pF 25pF 220Ω 2k Q11 Q33 18k Q12 Q10 Q9 Q8 100k D5 20Ω 20Ω Q13 Q25 Q26 4k 6.8k 12k 250Ω Q23 480Ω 12k 5pF Q22 Q21 2pF 15k 12k Q20 Q18 Q24 Q19 150Ω 1k Q14 Q27 Q28 Q31 Q30 270Ω Q16 100Ω 0.02Ω 2k Q17 8k 20k Q29 6k Q15 600Ω 10Ω 4.2k 4k 1k 100Ω 1k 2.
PAGE 11
LT137A/LM137 LT337A/LM337 PACKAGE DESCRIPTION OBSOLETE PACKAGES H Package 3-Lead TO-39 Metal Can (Reference LTC DWG # 05-08-1330) .350 – .370 (8.890 – 9.398) .305 – .335 (7.747 – 8.509) .050 (1.270) MAX .165 – .185 (4.191 – 4.699) REFERENCE PLANE * .016 – .019** (0.406 – 0.483) DIA .500 (12.700) MIN .200 (5.080) TYP .100 (2.540) PIN 1 .029 – .045 (0.737 – 1.143) .100 (2.540) .028 – .034 (0.711 – 0.864) 45o H3(TO-39) 0801 *LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE AND .
PAGE 12
LT137A/LM137 LT337A/LM337 PACKAGE DESCRIPTION M Package 3-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1460) .060 (1.524) TYP .390 – .415 (9.906 – 10.541) .165 – .180 (4.191 – 4.572) 15° TYP .045 – .055 (1.143 – 1.397) .330 – .370 (8.382 – 9.398) .218 – .252 (5.537 – 6.401) .520 – .570 (13.208 – 14.478) .090 – .110 (2.286 – 2.794) .013 – .023 (0.330 – 0.584) .050 (1.270) TYP .028 – .038 (0.711 – 0.965) .095 – .115 (2.413 – 2.921) .420 .080 .420 .276 .325 .350 .205 .565 .565 .320 .090 .