LM138K芯片引脚定义引脚图及功能IC贸易商引脚图技术参数-中国IC网-芯三七

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产品型号LM138K的概述

LM138K芯片的概述 LM138K是一款广泛应用于线性稳压器系列的集成电路（IC），主要用于提供相对稳定的直流电压输出。作为一种可调式三端稳压器，LM138K不仅具备良好的电压调节能力，而且拥有较高的负载电流输出能力，非常适合应用于各类电子设备中。该芯片特别设计用于需要高电流输出的场合，并且具有过载保护、短路保护等多种安全功能，保障了电路的稳定性和安全性。 LM138K的详细参数 LM138K的主要电气参数包括： - 输出电压范围：1.25V至37V，可根据外部电阻配置进行调节。 - 输出电流：最大可提供1.5A的电流，适合大多数中低功率应用。 - 输入电压：最大的输入电压可达40V，因而具有较高的灵活性。 - 温度范围：工作温度范围为-40°C至+125°C，适合于各类恶劣环境中使用。 - 功耗：典型功耗在合理范围内，一般情况下不会显著影响整机的能耗。 - 调节率：有良好的调节率，...

产品型号LM138K的Datasheet PDF文件预览

LM138/238

LM338

THREE-TERMINAL 5-A

ADJUSTABLE VOLTAGE REGULATORS

GUARANTEED 7A PEAK OUTPUT CURRENT

GUARANTEED 5A OUTPUT CURRENT

ADJUSTABLE OUTPUT DOWN TO 1.2V

LINE REGULATION TYPICALLY 0.005% /V

LOAD REGULATION TYPICALLY 0.1%

GUARANTEED THERMAL REGULATION

CURRENT LIMIT CONSTANT WITH TEM-

PERATURE

STANDARD 3-LEAD TRANSISTOR PACKAGE

DESCRIPTION

The LM138/LM238/LM338 are adjustable 3-terminal

positive voltageregulators capable of supplying in ex-

cess of 5A over a 1.2V to 32V output range. They are

exceptionally easy to use and require only 2 resistors

toset the output voltage. Careful circuitdesign has re-

sulted in outstanding load and line regulation com-

parable to many commercial power supplies. The

LM138 family is supplied in a standard 3-lead transis-

tor package.

TO3

K SUFFIX

(Steel Can)

ORDER CODE

A unique feature of the LM138 family is time-de-

pendent current limiting. The current limit circuitry

allowspeak currents of upto 12A tobe drawn fromthe

regulator for short periods of time. This allows the

LM138 to be used with heavy transient loads and

speedsstart-up under full-load conditions. Under sus-

tained loading conditions, the current limit decreases

to a safe value protecting the regulator. Also included

on the chip are thermal overload protection and safe

area protection for thepower transistor. Overloadpro-

tection remains functional even if the adjustment pin

is accidentally disconnected.

Normally, nocapacitors are needed unless thedevice

is situated far from the input filter capacitors in which

case an input bypass is needed. An optional output

capacitor can be added to improve transient res-

ponse. The adjustment terminal can be bypassed to

achieve very high ripple rejection ratios which are dif-

ficult to achieve with standard 3-terminal regulators.

Besidesreplacing fixedregulators ordiscretedesigns,

the LM238 is useful in a wide variety of other applica-

tions. Since the regulator is ”floating” and sees only

theinput-to-output differential voltage, supplies of sev-

eral hundred volts can be regulated as long as the

maximum input to input differential is not exceeded.

The LM138/LM238/LM338 are packaged in standard

steel TO-3 transistor packages. The LM138 is rated

for operation from -55 ^oC to 150 ^oC, the LM238 from

– 25°C to + 150°C and the LM338 from 0°C to +

125°C.

PART

NUMBER

TEMPERATURE

RANGE

PACKAGE

LM138

LM238

LM338

-55 C to + 150 C

•

-25 C to + 150 C

0 C to + 125 C

EXAMPLE: LM138K

PIN CONNECTION

(bottom view)

Case is output

March 1993

1/12

LM138-LM238-LM338

ABSOLUTE MAXIMUM RATING

Symbol

Parameter

Value

Internally Limited

Unit

P_tot

Power Dissipation

V_I- V_OInput-Output Voltage DIfferential

^oC

T_operOperating Junction Temperature Range

LM138

LM238

LM338

-55 to 150

-25 to 150

0 to 125

T_stg

Storage Temperature Range

-65 to 150

300

^oC

T_lead

Lead Temperature (Soldering, 10 seconds)

THERMAL CHARACTERISTICS

Symbol

Parameter

Value

1.4

Unit

^oC/W

R_th(j-c)Typical Junction-Case Thermal Resistance

R_th(j-a)Max Junction-Ambient Thermal Resistance

SCHEMATIC DIAGRAM

2/12

LM138-LM238-LM338

ELECTRICAL CHARACTERISTICS

LM138: -55 ≤ T_j≤ 150 C, V_I- V_O= 5V, I_O= 2.5A

LM238: -25 ≤ T_j≤ 150 C, V_I- V_O= 5V, I_O= 2.5A

LM338: 0 ≤ T_j≤ 150 C, V_I- V_O= 5V, I_O= 2.5A

Although power dissipation is internally limited, these specifications apply to power dissipation up to

50W (unless otherwise specified).

Symbol

K_VI

Parameter

LM138-LM238

LM338

Typ.

0.005 0.03

Unit

Min.

Typ.

Max.

Min.

Max.

Line Regulation - (note 1)

0.005 0.01

%/V

T_amb= 25 ^oC, 3 V ≤ (V_I- V_O) ≤ 35 V

K_VO

Load Regulation T_amb= 25 ^oC, 10 mA ≤ I_O≤ 5 A

V_O≤ 5V - (note 1)

0.1

0.5

V_O≥ 5V - (note 1)

0.1

0.3

Thermal Regulation (pulse = 20 ms)

Adjustment Pin Current

Adjustment Pin Current Change

0.002 0.01

0.002 0.02

%/W

µA

I_adj

∆I_adj

100

0.2

10 mA ≤ I_L≤ 5 A, 3 V ≤ (V_I- V_O) ≤ 35 V

v_(ref)

K_VI

Reference Voltage

3V ≤ (V_I- V_O) ≤ 35 V, 10 mA ≤ I_O≤ 5A, P ≤ 50W

Line Regulation - (note 1)

1.19

1.24

0.02

1.29

0.04

1.19

1.24

0.02

1.29

0.06

%/V

3 V ≤ (V_I- V_O) ≤ 35 V

K_VO

Load Regulation 10 mA ≤ I_O≤ 5 A

V_O≤ 5V - (note 1)

0.3

0.6

0.3

V_O≥ 5V - (note 1)

Temperature Stability (T_min≤ T_j≤ T_max

K_VT

)

I_O(min)Minimum Load Current (V_I- V_O≤ 35 V)

I_O(max)Current Limit (V_I- V_O≤ 10 V)

3.5

0.003

3.5

0.003

0.5 ms Peak

V_I- V_O= 30 V

RMS Output Noise, % of V_O

(T_amb= 25 ^oC, 10 Hz ≤ f ≤ 10 KHz)

R_vf

Ripple Rejection Ratio

V_O= 10 V, f = 120 Hz

C_adi= 10 µF

Long Term Stability (T_amb= 125 ^oC)

0.3

K_VH

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.

3/12

LM138-LM238-LM338

4/12

LM138-LM238-LM338

5/12

LM138-LM238-LM338

TYPICAL APPLICATIONS

Since the 50µA current from the adjustment termi-

nal represents an error term, the LM338 was de-

signed to minimize I_adjand make it very constant

with line and load changes. To do this, allquiescent

operating current is returned to the output establi-

shing a minimum load current requirement. If there

is insufficient load on the output, the outputwill rise.

+ 1.2V to + 25V ADJUSTABLE REGULATOR

EXTERNAL CAPACITORS

An input bypass capacitor is recommended. A

0.1µF disc or 1µF solid tantalum on the input is suit-

able input by passing for almost all applications.

The device ismore sensitiveto the 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 LM338 to improve ripple rejection.

This bypass capacitor prevents ripple form being

amplified as the output voltage is increased. With

a 10µF bypass capacitor 75dB ripple rejection is

obtainable at any output level. 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 pro-

tection diodes to prevent the capacitor from dis-

charging through internal low current paths and

damaging the device.

∆ 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

commonly used to provide improved output impedance and rejec-

tion of tran-sients.

* * V_O= 1.25V (1 +

)

* * * R1 = 240Ω for LM138 and LM238

APPLICATION HINTS

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 25µF in

aluminum electrolyticto equal1µF 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, 0.01µF disc may

seem to work better than a 0.1µF disc as a bypass.

In operation, the LM338 develops a nominal 1.25V

reference voltage, V_(ref), between the output and

adjustment terminal. The reference voltage is im-

pressed across program resistor R1 and, since the

voltage is constant, a constant current I₁then flows

through the output set resistor R2, giving an output

voltage of

R₂

V_O= V_(ref)( 1+

) + I_adjR₂

R₁

Although the LM338 is stable with no output capa-

citors, like any feedback circuit, certain values of

external capacitance can 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.

Figure 1.

LOAD REGULATION

The LM338 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 termi-

nal and the output terminal (usually 240Ω) 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 0.05Ω resistance between the regu-

lator and load will have a load regulation due to line

resistance of 0.05Ω x I_L. If the set resistor is con-

nected near the load the effective line resistance

6/12

LM138-LM238-LM338

will be 0.05Ω (1 + R₂/R₁) or in this case, 11.5 times

20µF capacitors have low enough internal series re-

sistance to deliver 20A spikes when shorted. Al-

thoughthe surge is short, there is enough energy to

damage parts of the IC.

worse.

Figure 2 shows the effect of resistance between the

regulator and 140Ω set resistor.

When an output capacitor is connected to a regula-

tor and the input is shorted, the output capacitor will

discharge into the output of the regulator. The dis-

charge current depends on the value of the capaci-

tor, the output voltage of the regulator, and the rate

of decrease of V_I. In the LM338 this discharge path

is through a large junction that is able to sustain 25A

surge withno problem. Thisis not true 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.

With the TO-3 package, it is easy tominimize the re-

sistance 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 regula-

tion.

PROTECTION DIODES

When external capacitors are used withany IC regu-

lator it is sometimes necessary to add protection

diodes to prevent the capacitors from discharging

through low current points into the regulator. Most

The bypass capacitor on the adjustment terminal

can discharge through a low current junction. Dis-

charge occurs when either the input or output is

shorted. Internal to the LM338 is a 50Ω resistor

which limits the peak discharge current. No protec-

tion is needed for output voltages of 25V or less and

10µF capacitance. Figure 3 shows an LM338 with

protection diodes included for use with outputs

greater than 25V and high values of output capacit-

ance.

Figure 2 : Regulator with Line Resistance in Out-

put Lead.

Figure 3 : Regulator with Protection Diodes.

7/12

LM138-LM238-LM338

10A REGULATOR

Minimum load – 100mA

V_I≥ 10V

V₀≥ 3V

V_I– V₀≥ 3.5V

5A CURRENT REGULATOR

Minimum load – 100mA

V_I≥ 10V

V₀≥ 3V

V_I– V₀≥ 3.5V

8/12

LM138-LM238-LM338

15A REGULATOR

Minimum load – 100mA

V_I≥ + 10V

V₀≥ + 3V

V_I– V₀≥ + 4V

5V LOGIC REGULATOR WITH ELECTRONIC SHUTDOWN**

R1 = 240Ω for LM138 or LM238

R2 = 720Ω for LM138 or LM238

Minimum output ≈ + 1.2V

9/12

LM138-LM238-LM338

TRACKING PREREGULATOR

R1 = 240Ω for LM138 or LM238

R2 = 720Ω for LM138 or LM238

Minimum output ≈ + 1.2V

SLOW TURN-ON 15V REGULATOR

R1 = 240Ω

R2 = 2.7kΩ

} for LM138 and LM238

10/12

LM138-LM238-LM338

TO-3 MECHANICAL DATA

inch

DIM.

MIN.

11.00

0.97

TYP.

MAX.

13.10

1.15

MIN.

0.433

0.038

0.059

0.327

0.748

0.421

0.649

0.984

0.157

1.515

1.187

TYP.

MAX.

0.516

0.045

0.065

0.351

0.787

0.437

0.677

1.023

0.161

1.547

1.193

1.50

1.65

8.32

8.92

19.00

10.70

16.50

25.00

4.00

20.00

11.10

17.20

26.00

4.09

38.50

30.00

39.30

30.30

P003F

11/12

LM138-LM238-LM338

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. Specificationsmentioned

in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.

SGS-THOMSON Microelectronicsproductsare notauthorized foruse ascritical componentsin life support devices or systems without express

written approval of SGS-THOMSON Microelectonics.

SGS-THOMSON Microelectronics GROUP OF COMPANIES

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LM138K产品参数

型号:	LM138K
是否Rohs认证：	不符合
生命周期：	Transferred
IHS 制造商：	INTEGRATED POWER SEMICONDUCTORS LTD
包装说明：	, TO-204/-3
Reach Compliance Code：	unknown
风险等级：	5.87
可调性：	ADJUSTABLE
输出次数：	1
端子数量：	3
工作温度TJ-Max：	150 °C
工作温度TJ-Min：	-55 °C
最大输出电压 1：	32 V
最小输出电压 1：	1.2 V
封装主体材料：	METAL
封装等效代码：	TO-204/-3
认证状态：	Not Qualified
子类别：	Other Regulators
技术：	BIPOLAR

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产品型号LM138K的概述

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