LM4128_08 [NSC]

Precision Micropower Series Voltage Reference; 精密微功耗系列电压基准


型号：	LM4128_08
厂家：	National Semiconductor
描述：	Precision Micropower Series Voltage Reference 精密微功耗系列电压基准
文件：	总18页 (文件大小：412K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

October 23, 2008

LM4128/LM4128Q

SOT-23 Precision Micropower Series Voltage Reference

General Description

Features

Ideal for space critical applications, the LM4128 precision

voltage reference is available in the SOT-23 surface-mount

package. The LM4128’s advanced design eliminates the

need for an external stabilizing capacitor while ensuring sta-

bility with capacitive loads up to 10 µF, thus making the

LM4128 easy to use.

Output voltage initial accuracy 0.1%

■

Low temperature coefficient 75 ppm/°C

Low Supply Current, 60 µA

Enable pin allowing a 3 µA shutdown mode

Up to 20 mA output current

Voltage options 1.8V, 2.048V, 2.5V, 3.0V, 3.3V, 4.096V

Series references provide lower power consumption than

shunt references, since they do not have to idle the maximum

possible load current under no load conditions. This advan-

tage, the low quiescent current (60 µA), and the low dropout

voltage (400 mV) make the LM4128 ideal for battery-powered

solutions.

Custom voltage options available (1.8V to 4.096V)

V_INrange of V_REF+ 400 mV to 5.5V @10 mA

Stable with low ESR ceramic capacitors

SOT23-5 Package

−40°C to 125°C junction temperature range

The LM4128 is available in four grades (A, B, C, and D) for

greater flexibility. The best grade devices (A) have an initial

accuracy of 0.1% with guaranteed temperature coefficient of

75 ppm/°C or less, while the lowest grade parts (D) have an

initial accuracy of 1.0% and a tempco of 100 ppm/°C.

LM4128AQ/BQ/CQ/DQ are AEC-Q100 Grade 1 qualified

and are manufactured on an Automotive Grade Flow

Applications

Instrumentation & Process Control

■

Test Equipment

Data Acquisition Systems

Base Stations

Servo Systems

Portable, Battery Powered Equipment

Automotive & Industrial Electronics

Precision Regulators

Battery Chargers

■

Communications

Medical Equipment

Typical Application Circuit

20211001

*Note: The capacitor C_INis required and the capacitor C_OUTis optional.

202110

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Connection Diagram

Ordering Information

Top View

20211002

SOT23-5 Package

NS Package Number MF05A

Input Output Voltage

Accuracy at 25°C And

Temperature Coefficient

LM4128 Supplied as

1000 units, Tape and

Reel

LM4128 Supplied as Part Marking

3000 units, Tape and

Reel

Feature

LM4128AMF-1.8

LM4128AMF-2.0

LM4128AMF-2.5

LM4128AMF-3.0

LM4128AMF-3.3

LM4128AMF-4.1

LM4128BMF-1.8

LM4128BMF-2.0

LM4128BMF-2.5

LM4128BMF-3.0

LM4128BMF-3.3

LM4128BMF-4.1

LM4128CMF-1.8

LM4128CMF-2.0

LM4128CMF-2.5

LM4128CMF-3.0

LM4128CMF-3.3

LM4128CMF-4.1

LM4128DMF-1.8

LM4128DMF-2.0

LM4128DMF-2.5

LM4128DMF-3.0

LM4128DMF-3.3

LM4128DMF-4.1

LM4128AMFX-1.8

LM4128AMFX-2.0

LM4128AMFX-2.5

LM4128AMFX-3.0

LM4128AMFX-3.3

LM4128AMFX-4.1

LM4128BMFX-1.8

LM4128BMFX-2.0

LM4128BMFX-2.5

LM4128BMFX-3.0

LM4128BMFX-3.3

LM4128BMFX-4.1

LM4128CMFX-1.8

LM4128CMFX-2.0

LM4128CMFX-2.5

LM4128CMFX-3.0

LM4128CMFX-3.3

LM4128CMFX-4.1

LM4128DMFX-1.8

LM4128DMFX-2.0

LM4128DMFX-2.5

LM4128DMFX-3.0

LM4128DMFX-3.3

LM4128DMFX-4.1

R5AA

R5BA

R5CA

R5DA

R5EA

R5FA

R5AB

R5BB

R5CB

R5DB

R5EB

R5FB

R5AC

R5BC

R5CC

R5DC

R5EC

R5FC

R5AD

R5BD

R5CD

R5DD

R5ED

R5FD

0.1%, 75 ppm/°C (A grade)

0.2%, 75 ppm/°C (B grade)

0.5%, 100 ppm/°C (C grade)

1.0%, 100 ppm/°C max

(D grade)

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Input Output Voltage

Accuracy at 25°C And

Temperature Coefficient

LM4128 Supplied as

1000 units, Tape and

Reel

LM4128 Supplied as Part Marking

3000 units, Tape and

Reel

Feature

LM4128AQ1MF1.8

LM4128AQ1MF2.0

LM4128AQ1MF2.5

LM4128AQ1MF3.0

LM4128AQ1MF3.3

LM4128AQ1MF4.1

LM4128BQ1MF1.8

LM4128BQ1MF2.0

LM4128BQ1MF2.5

LM4128BQ1MF3.0

LM4128BQ1MF3.3

LM4128BQ1MF4.1

LM4128CQ1MF1.8

LM4128CQ1MF2.0

LM4128CQ1MF2.5

LM4128CQ1MF3.0

LM4128CQ1MF3.3

LM4128CQ1MF4.1

LM4128DQ1MF1.8

LM4128DQ1MF2.0

LM4128DQ1MF2.5

LM4128DQ1MF3.0

LM4128DQ1MF3.3

LM4128DQ1MF4.1

LM4128AQ1MFX1.8

LM4128AQ1MFX2.0

LM4128AQ1MFX2.5

LM4128AQ1MFX3.0

LM4128AQ1MFX3.3

LM4128AQ1MFX4.1

LM4128BQ1MFX1.8

LM4128BQ1MFX2.0

LM4128BQ1MFX2.5

LM4128BQ1MFX3.0

LM4128BQ1MFX3.3

LM4128BQ1MFX4.1

LM4128CQ1MFX1.8

LM4128CQ1MFX2.0

LM4128CQ1MFX2.5

LM4128CQ1MFX3.0

LM4128CQ1MFX3.3

LM4128CQ1MFX4.1

LM4128DQ1MFX1.8

LM4128DQ1MFX2.0

LM4128DQ1MFX2.5

LM4128DQ1MFX3.0

LM4128DQ1MFX3.3

LM4128DQ1MFX4.1

R6AA

R6BA

R6CA

R6DA

R6EA

R6FA

R6AB

R6BB

R6CB

R6DB

R6EB

R6FB

R6AC

R6BC

R6CC

R6DC

R6EC

R6FC

R6AD

R6BD

R6CD

R6DD

R6ED

R6FD

AEC-Q100 Grade 1

qualified. Automotive

Grade Production Flow*

0.1%, 75 ppm/°C

(AQ grade)

AEC-Q100 Grade 1

qualified. Automotive

Grade Production Flow*

0.2%, 75 ppm/°C

(BQ grade)

AEC-Q100 Grade 1

qualified. Automotive

Grade Production Flow*

0.5%, 100 ppm/°C

(CQ grade)

AEC-Q100 Grade 1

qualified. Automotive

Grade Production Flow*

1.0%, 100 ppm/°C max

(DQ grade)

*Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies.

Reliability qualification is compliant with the requirements and temperature grades defined in the AEC-Q100 standard. Automotive grade products are identified

with the letter Q. For more information go to http://www.national.com/automotive.

Pin Descriptions

Pin #

Name

N/C

Function

No connect pin, leave floating

Ground

GND

Enable pin

VIN

Input supply

VREF

Reference output

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Vapor Phase (60 sec)

Infrared (15sec)

ESD Susceptibility (Note 3)

Human Body Model

215°C

220°C

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

2 kV

Maximum Voltage on any input

Output short circuit duration

Power Dissipation (T_A= 25°C)

(Note 2)

-0.3 to 6V

Indefinite

Operating Ratings

Maximum Input Supply Voltage

Maximum Enable Input Voltage

Maximum Load Current

5.5V

V_IN

350 mW

−65°C to 150°C

20mA

−40°C to

+125°C

Storage Temperature Range

Junction Temperature Range (T_J)

ꢀ

Lead Temperature (soldering, 10sec)

260°C

Electrical Characteristics

LM4128-1.8 (V_OUT= 1.8V) Limits in standard type are for T_J= 25°C only, and limits in boldface type apply over

the junction temperature (T_J) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed

through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T_J= 25°C, and are

provided for reference purposes only. Unless otherwise specified V_IN= 5V and I_LOAD= 0A.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

(Note 4) (Note 5) (Note 4)

V_REF

Output Voltage Initial Accuracy

LM4128A-1.8

(A Grade - 0.1%)

-0.1

-0.2

-0.5

-1.0

+0.1

+0.2

+0.5

+1.0

LM4128B-1.8

(B Grade - 0.2%)

(C Grade - 0.5%)

(D Grade - 1.0%)

LM4128A-1.8

LM4128C-1.8

LM4128D-1.8

TCV_REF/ °C (Note Temperature Coefficient

LM4128B-1.8

ppm / °C

LM4128C-1.8

100

LM4128D-1.8

I_Q

Supply Current

µA

I_{Q_SD}

Supply Current in Shutdown

Line Regulation

EN = 0V

ppm / V

ΔV_REF/ΔV_IN

V_REF+ 400 mV ≤ V_IN≤ 5.5V

Load Regulation

120

400

ppm / mA

ppm

ΔV_REF/ΔI_LOAD

ΔV_REF

0 mA ≤ I_LOAD≤ 20 mA

1000 Hrs

Long Term Stability (Note 7)

Thermal Hysteresis (Note 8)

-40°C ≤ T_J≤ +125°C

I_LOAD= 10 mA

V_IN- V_REF

Dropout Voltage (Note 9)

200

170

µV_PP

V_N

I_SC

V_IL

V_IH

Output Noise Voltage

0.1 Hz to 10 Hz

Short Circuit Current

Enable Pin Maximum Low Input Level

Enable Pin Minimum High Input Level

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Electrical Characteristics

LM4128-2.0 (V_OUT= 2.048V) Limits in standard type are for T_J= 25°C only, and limits in boldface type apply

over the junction temperature (T_J) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are

guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T_J= 25°C,

and are provided for reference purposes only. Unless otherwise specified V_IN= 5V and I_LOAD= 0A.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

(Note 4) (Note 5) (Note 4)

V_REF

Output Voltage Initial Accuracy

LM4128A-2.0

(A Grade - 0.1%)

-0.1

-0.2

-0.5

-1.0

+0.1

+0.2

+0.5

+1.0

LM4128B-2.0

(B Grade - 0.2%)

(C Grade - 0.5%)

(D Grade - 1.0%)

LM4128A-2.0

LM4128C-2.0

LM4128D-2.0

TCV_REF/ °C (Note Temperature Coefficient

LM4128B-2.0

ppm / °C

LM4128C-2.0

100

LM4128D-2.0

I_Q

Supply Current

µA

I_{Q_SD}

Supply Current in Shutdown

Line Regulation

EN = 0V

ppm / V

ΔV_REF/ΔV_IN

V_REF+ 400 mV ≤ V_IN≤ 5.5V

Load Regulation

120

400

ppm / mA

ppm

ΔV_REF/ΔI_LOAD

ΔV_REF

0 mA ≤ I_LOAD≤ 20 mA

1000 Hrs

Long Term Stability (Note 7)

Thermal Hysteresis (Note 8)

-40°C ≤ T_J≤ +125°C

I_LOAD= 10 mA

V_IN- V_REF

Dropout Voltage (Note 9)

175

190

µV_PP

V_N

I_SC

V_IL

V_IH

Output Noise Voltage

0.1 Hz to 10 Hz

Short Circuit Current

Enable Pin Maximum Low Input Level

Enable Pin Minimum High Input Level

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Electrical Characteristics

LM4128-2.5 (V_OUT= 2.5V) Limits in standard type are for T_J= 25°C only, and limits in boldface type apply over

the junction temperature (T_J) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed

through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T_J= 25°C, and are

provided for reference purposes only. Unless otherwise specified V_IN= 5V and I_LOAD= 0A.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

(Note 4) (Note 5) (Note 4)

V_REF

Output Voltage Initial Accuracy

LM4128A-2.5

(A Grade - 0.1%)

-0.1

-0.2

-0.5

-1.0

+0.1

+0.2

+0.5

+1.0

LM4128B-2.5

(B Grade - 0.2%)

(C Grade - 0.5%)

(D Grade - 1.0%)

LM4128A-2.5

LM4128C-2.5

LM4128D-2.5

TCV_REF/ °C (Note Temperature Coefficient

LM4128B-2.5

ppm / °C

LM4128C-2.5

100

LM4128D-2.5

I_Q

Supply Current

µA

I_{Q_SD}

Supply Current in Shutdown

Line Regulation

EN = 0V

ppm / V

ΔV_REF/ΔV_IN

V_REF+ 400 mV ≤ V_IN≤ 5.5V

Load Regulation

120

400

ppm / mA

ppm

ΔV_REF/ΔI_LOAD

ΔV_REF

0 mA ≤ I_LOAD≤ 20 mA

1000 Hrs

Long Term Stability (Note 7)

Thermal Hysteresis (Note 8)

-40°C ≤ T_J≤ +125°C

I_LOAD= 10 mA

V_IN- V_REF

Dropout Voltage (Note 9)

175

275

µV_PP

V_N

I_SC

V_IL

V_IH

Output Noise Voltage

0.1 Hz to 10 Hz

Short Circuit Current

Enable Pin Maximum Low Input Level

Enable Pin Minimum High Input Level

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Electrical Characteristics

LM4128-3.0 (V_OUT= 3.0V) Limits in standard type are for T_J= 25°C only, and limits in boldface type apply over

the junction temperature (T_J) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed

through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T_J= 25°C, and are

provided for reference purposes only. Unless otherwise specified V_IN= 5V and I_LOAD= 0A.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

(Note 4) (Note 5) (Note 4)

V_REF

Output Voltage Initial Accuracy

LM4128A-3.0

(A Grade - 0.1%)

-0.1

-0.2

-0.5

-1.0

+0.1

+0.2

+0.5

+1.0

LM4128B-3.0

(B Grade - 0.2%)

(C Grade - 0.5%)

(D Grade - 1.0%)

LM4128A-3.0

LM4128C-3.0

LM4128D-3.0

TCV_REF/ °C (Note Temperature Coefficient

LM4128B-3.0

ppm / °C

LM4128C-3.0

100

LM4128D-3.0

I_Q

Supply Current

µA

I_{Q_SD}

Supply Current in Shutdown

Line Regulation

EN = 0V

ppm / V

ΔV_REF/ΔV_IN

V_REF+ 400 mV ≤ V_IN≤ 5.5V

Load Regulation

120

400

ppm / mA

ppm

ΔV_REF/ΔI_LOAD

ΔV_REF

0 mA ≤ I_LOAD≤ 20 mA

1000 Hrs

Long Term Stability (Note 7)

Thermal Hysteresis (Note 8)

-40°C ≤ T_J≤ +125°C

I_LOAD= 10 mA

V_IN- V_REF

Dropout Voltage (Note 9)

175

285

µV_PP

V_N

I_SC

V_IL

V_IH

Output Noise Voltage

0.1 Hz to 10 Hz

Short Circuit Current

Enable Pin Maximum Low Input Level

Enable Pin Minimum High Input Level

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Electrical Characteristics

LM4128-3.3 (V_OUT= 3.3V) Limits in standard type are for T_J= 25°C only, and limits in boldface type apply over

the junction temperature (T_J) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed

through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T_J= 25°C, and are

provided for reference purposes only. Unless otherwise specified V_IN= 5V and I_LOAD= 0A.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

(Note 4) (Note 5) (Note 4)

V_REF

Output Voltage Initial Accuracy

LM4128A-3.3

(A Grade - 0.1%)

-0.1

-0.2

-0.5

-1.0

+0.1

+0.2

+0.5

+1.0

LM4128B-3.3

(B Grade - 0.2%)

(C Grade - 0.5%)

(D Grade - 1.0%)

LM4128A-3.3

LM4128C-3.3

LM4128D-3.3

TCV_REF/ °C (Note Temperature Coefficient

LM4128B-3.3

ppm / °C

LM4128C-3.3

100

LM4128D-3.3

I_Q

Supply Current

µA

I_{Q_SD}

Supply Current in Shutdown

Line Regulation

EN = 0V

ppm / V

ΔV_REF/ΔV_IN

V_REF+ 400 mV ≤ V_IN≤ 5.5V

Load Regulation

120

400

ppm / mA

ppm

ΔV_REF/ΔI_LOAD

ΔV_REF

0 mA ≤ I_LOAD≤ 20 mA

1000 Hrs

Long Term Stability (Note 7)

Thermal Hysteresis (Note 8)

-40°C ≤ T_J≤ +125°C

I_LOAD= 10 mA

V_IN- V_REF

Dropout Voltage (Note 9)

175

310

µV_PP

V_N

I_SC

V_IL

V_IH

Output Noise Voltage

0.1 Hz to 10 Hz

Short Circuit Current

Enable Pin Maximum Low Input Level

Enable Pin Minimum High Input Level

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Electrical Characteristics

LM4128-4.1 (V_OUT= 4.096V) Limits in standard type are for T_J= 25°C only, and limits in boldface type apply

over the junction temperature (T_J) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are

guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T_J= 25°C,

and are provided for reference purposes only. Unless otherwise specified V_IN= 5V and I_LOAD= 0A.

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

(Note 4) (Note 5) (Note 4)

V_REF

Output Voltage Initial Accuracy

LM4128A-4.1

(A Grade - 0.1%)

-0.1

-0.2

-0.5

-1.0

+0.1

+0.2

+0.5

+1.0

LM4128B-4.1

(B Grade - 0.2%)

(C Grade - 0.5%)

(D Grade - 1.0%)

LM4128A-4.1

LM4128C-4.1

LM4128D-4.1

TCV_REF/ °C (Note Temperature Coefficient

LM4128B-4.1

ppm / °C

LM4128C-4.1

100

LM4128D-4.1

I_Q

Supply Current

µA

I_{Q_SD}

Supply Current in Shutdown

Line Regulation

EN = 0V

100

ppm / V

ΔV_REF/ΔV_IN

V_REF+ 400 mV ≤ V_IN≤ 5.5V

Load Regulation

120

400

ppm / mA

ppm

ΔV_REF/ΔI_LOAD

ΔV_REF

0 mA ≤ I_LOAD≤ 20 mA

1000 Hrs

Long Term Stability (Note 7)

Thermal Hysteresis (Note 8)

-40°C ≤ T_J≤ +125°C

I_LOAD= 10 mA

V_IN- V_REF

Dropout Voltage (Note 9)

175

350

µV_PP

V_N

I_SC

V_IL

V_IH

Output Noise Voltage

0.1 Hz to 10 Hz

Short Circuit Current

Enable Pin Maximum Low Input Level

Enable Pin Minimum High Input Level

Note 1: Absolute Maximum Ratings indicate limits beyond which damage may occur to the device. Operating Ratings indicate conditions for which the device is

intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications, see Electrical Characteristics.

Note 2: Without PCB copper enhancements. The maximum power dissipation must be de-rated at elevated temperatures and is limited by T_JMAX(maximum

junction temperature), θ_J-A(junction to ambient thermal resistance) and T_A(ambient temperature). The maximum power dissipation at any temperature is:

P_DissMAX= (T_JMAX- T_A) /θ_J-Aup to the value listed in the Absolute Maximum Ratings. θ_J-Afor SOT23-5 package is 220°C/W, T_JMAX= 125°C.

Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.

Note 4: Limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality

Control.

Note 5: Typical numbers are at 25°C and represent the most likely parametric norm.

Note 6: Temperature coefficient is measured by the "Box" method; i.e., the maximum ΔV_REFis divided by the maximum ΔT.

Note 7: Long term stability is V_REF@25°C measured during 1000 hrs.

Note 8: Thermal hysteresis is defined as the change in +25°C output voltage before and after cycling the device from (-40°C to 125°C).

Note 9: Dropout voltage is defined as the minimum input to output differential at which the output voltage drops by 0.5% below the value measured with a 5V

input.

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Typical Performance Characteristics for 2.5V

Output Voltage vs Temperature

Load Regulation

20211054

20211055

Line Regulation

0.1 - 10 Hz Noise

20211021

20211056

Output Voltage Noise Spectrum

Power Supply Rejection Ratio vs Frequency

20211057

20211058

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Dropout vs Load to 0.5% Accuracy

Typical Long Term Stability

20211008

20211030

Supply Current vs Input Voltage

Shutdown I_Qvs Input Voltage

20211010

20211053

Ground Current vs Load Current

Line Transient Response

V_IN= 3V to 5V

20211051

20211018

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Load Transient Response

I_LOAD= 0 to 10mA

Short-Circuit Protection and Recovery

20211082

20211050

Start-Up Response

20211083

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THERMAL HYSTERESIS

Application Information

Thermal hysteresis is defined as the change in output voltage

at 25ºC after some deviation from 25ºC. This is to say that

thermal hysteresis is the difference in output voltage between

two points in a given temperature profile. An illustrative tem-

perature profile is shown in Figure 1.

THEORY OF OPERATION

The foundation of any voltage reference is the band-gap cir-

cuit. While the reference in the LM4128 is developed from the

gate-source voltage of transistors in the IC, principles of the

band-gap circuit are easily understood using a bipolar exam-

ple. For a detailed analysis of the bipolar band-gap circuit,

please refer to Application Note AN-56.

SUPPLY AND ENABLE VOLTAGES

To ensure proper operation, V_ENand V_INmust be within a

specified range. An acceptable range of input voltages is

V_IN> V_REF+ 400 mV (I_LOAD≤ 10 mA)

The enable pin uses an internal pull-up current source

(I_{PULL_UP}≊ 2 µA) that may be left floating or triggered by an

external source. If the part is not enabled by an external

source, it may be connected to V_IN. An acceptable range of

enable voltages is given by the enable transfer characteris-

tics. See the Electrical Characteristics section and Enable

Transfer Characteristics figure for more detail. Note, the part

will not operate correctly for V_EN> V_IN.

20211038

FIGURE 1. Illustrative Temperature Profile

This may be expressed analytically as the following:

COMPONENT SELECTION

A small ceramic (X5R or X7R) capacitor on the input must be

used to ensure stable operation. The value of C_INmust be

sized according to the output capacitor value. The value of

C_INmust satisfy the relationship C_IN≥ C_OUT. When no output

capacitor is used, C_INmust have a minimum value of 0.1 µF.

Noise on the power-supply input may affect the output noise.

Larger input capacitor values (typically 4.7 µF to 22 µF) may

help reduce noise on the output and significantly reduce over-

shoot during startup. Use of an additional optional bypass

capacitor between the input and ground may help further re-

duce noise on the output. With an input capacitor, the LM4128

will drive any combination of resistance and capacitance up

to V_REF/20 mA and 10 µF respectively.

Where

V_HYS= Thermal hysteresis expressed in ppm

V_REF= Nominal preset output voltage

V_REF1= V_REFbefore temperature fluctuation

V_REF2= V_REFafter temperature fluctuation.

The LM4128 features a low thermal hysteresis of 190 µV from

-40°C to 125°C.

TEMPERATURE COEFFICIENT

Temperature drift is defined as the maximum deviation in out-

put voltage over the operating temperature range. This devi-

ation over temperature may be illustrated as shown in Figure

The LM4128 is designed to operate with or without an output

capacitor and is stable with capacitive loads up to 10 µF.

Connecting a capacitor between the output and ground will

significantly improve the load transient response when

switching from a light load to a heavy load. The output ca-

pacitor should not be made arbitrarily large because it will

effect the turn-on time as well as line and load transients.

While a variety of capacitor chemistry types may be used, it

is typically advisable to use low esr ceramic capacitors. Such

capacitors provide a low impedance to high frequency sig-

nals, effectively bypassing them to ground. Bypass capacitors

should be mounted close to the part. Mounting bypass ca-

pacitors close to the part will help reduce the parasitic trace

components thereby improving performance.

SHORT CIRCUITED OUTPUT

The LM4128 features indefinite short circuit protection. This

protection limits the output current to 75 mA when the output

is shorted to ground.

20211039

FIGURE 2. Illustrative Temperature Coefficient Profile

TURN ON TIME

Temperature coefficient may be expressed analytically as the

following:

Turn on time is defined as the time taken for the output voltage

to rise to 90% of the preset value. The turn on time depends

on the load. The turn on time is typically 33.2 µs when driving

a 1µF load and 78.8 µs when driving a 10 µF load. Some users

may experience an extended turn on time (up to 10 ms) under

brown out conditions and low temperatures (-40°C).

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T_D= Temperature drift

V_REFis in volts (V), V_ERRORis in milli-volts (mV), and n is the

number of bits.

V_REF= Nominal preset output voltage

mV to ppm error in output voltage:

V_{REF_MIN}

temperature range

V_{REF_MAX}Maximum output voltage over operating

Minimum output voltage over operating

temperature range

ΔT = Operating temperature range.

The LM4128 features a low temperature drift of 75 ppm (max)

to 100 ppm (max), depending on the grade, from -40°C to

125°C.

Where:

V_REFis in volts (V) and V_ERRORis in milli-volts (mV).

Voltage error (mV) to percentage error (percent):

LONG TERM STABILITY

Long-term stability refers to the fluctuation in output voltage

over a long period of time (1000 hours). The LM4128 features

a typical long-term stability of 50 ppm over 1000 hours. The

measurements are made using 5 units of each voltage option,

at a nominal input voltage (5V), with no load, at room tem-

perature.

Where:

V_REFis in volts (V) and V_ERRORis in milli-volts (mV).

EXPRESSION OF ELECTRICAL CHARACTERISTICS

PRINTED CIRCUIT BOARD and LAYOUT

CONSIDERATIONS

Electrical characteristics are typically expressed in mV, ppm,

or a percentage of the nominal value. Depending on the ap-

plication, one expression may be more useful than the other.

To convert one quantity to the other one may apply the fol-

lowing:

References in SOT packages are generally less prone to PC

board mounting than devices in Small Outline (SOIC) pack-

ages. To minimize the mechanical stress due to PC board

mounting that can cause the output voltage to shift from its

initial value, mount the reference on a low flex area of the PC

board, such as near the edge or a corner.

ppm to mV error in output voltage:

The part may be isolated mechanically by cutting a U shape

slot on the PCB for mounting the device. This approach also

provides some thermal isolation from the rest of the circuit.

Bypass capacitors must be mounted close to the part. Mount-

ing bypass capacitors close to the part will reduce the para-

sitic trace components thereby improving performance.

Where:

V_REFis in volts (V) and V_ERRORis in milli-volts (mV).

Bit error (1 bit) to voltage error (mV):

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Typical Application Circuits

20211026

FIGURE 3. Voltage Reference with Complimentary Output

20211027

FIGURE 4. Precision Voltage Reference with Force and Sense Output

20211028

FIGURE 5. Programmable Current Source

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Physical Dimensions inches (millimeters) unless otherwise noted

SOT23-5 Package

NS Package Number MF05A

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Notes

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Notes

For more National Semiconductor product information and proven design tools, visit the following Web sites at:

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