IRU431ALCS [INFINEON]

Two Terminal Voltage Reference, 1 Output, 1.24V, Trim/Adjustable, BIPolar, PDSO8, PLASTIC, SOIC-8;


型号：	IRU431ALCS
厂家：	Infineon
描述：	Two Terminal Voltage Reference, 1 Output, 1.24V, Trim/Adjustable, BIPolar, PDSO8, PLASTIC, SOIC-8 光电二极管输出元件
文件：	总6页 (文件大小：39K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

IRU431L/IRU431AL

LOW -VOLTAGE ADJUSTABLE

PRECISION SHUNT REGULATOR

PRELIMINARY DATASHEET

FEATURES

DESCRIPTION

SOT23-5 package

The IRU431L is a three-terminal adjustable shunt regu-

lator that can also be used as a precision voltage refer-

ence. Its output voltage may be set to any value be-

tween Vref(1.24V) and 6V with two external resistors as

shown in the typical application circuit. Other applica-

tions of this device include the use as a merged ampli-

fier and reference in applications such as a linear regu-

lator or as the secondary side controller in low voltage

power supply applications. The IRU431L only requires

80mA maximum quiescent current before regulating, mak-

ing it ideal as a voltage reference for battery type appli-

cations.

0.5% Voltage Reference Initial Accuracy

(IRU431AL)

Low Operational Cathode Current

(80mA max)

Unconditionally Stable with only 1mF

Adjustable Output from 1.24V to 15V

0.25W Typical Output Impedance

Pin to Pin Compatible with TLV431

APPLICATIONS

Precision Voltage Reference

Linear Regulator Controller

Secondary Side Controller for the Low Voltage

Power Supply Applications

TYPICAL APPLICATION

IRU431

431app1-1.0

Vo = Vref ´ 1+

Typical application of the IRU431L as a shunt regulator / voltage reference

PACKAGE ORDER INFORMATION

Ta (°C)

5-LEAD

SOT23-5

IRU431LCL5

PKG

MARK

431L

3-LEAD

SOT-23

IRU431LCL3

PKG

MARK

431L

8-PIN PLASTIC

SOIC

0 TO 70

IRU431LCS

IRU431ALCS

IRU431ALCL5 431A

IRU431ALCL3 431A

Rev. 1.3

5/10/99

2-5

IRU431L/IRU431AL

ABSOLUTE MAXIMUM RATINGS

Input Voltage (V ) ................................................. 15V

Continuous Cathode Current Range ........................... -15mA to +15mA

Reference Current Range .......................................... -0.05mA to 1mA

Storage Temperature Range ..................................... -65°C TO 150°C

Operating Junction Temperature Range ......................

0°C TO 150°C

PACKAGE INFORMATION

5-PIN SOT-23 (L)

3-PIN SOT-23 (L3)

8-PIN PLASTIC SOIC (S)

TOP VIEW

Cathode

Ref

Cathode

Anode

Cathode

Ref

qJA = 450°C/W

qJA=160°C/W

ELECTRICAL SPECIFICATIONS

Unless otherwise specified, these specifications apply over Ta=0 to 70 °C, CO =1mF. Typical values refer to

Ta=25 °C. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the

ambient temperature.

PARAMETER

Reference Voltage

IRU431L

Reference Voltage

IRU431AL

Vref deviation over full

temperature range

Ratio of Vref change to

cathode voltage change

Reference pin current

Iref deviation over full

temperature range

Minimum cathode current

Off state cathode current

SYM

Vref

TEST CONDITION

IK=10mA, VKA=Vref, Ta=25°C

IK=10mA, VKA=Vref

IK=10mA, VKA=Vref, Ta=25°C

IK=10mA, VKA=Vref

VKA=Vref, IK=10mA

Note 1

MIN

TYP MAX

UNITS

1.228 1.240 1.252

1.221 1.240 1.259

1.234 1.240 1.246

1.228 1.240 1.252

Vref

Vref(dev)

dVref/dVKA IK=10mA, dVKA=Vref to 6 V

-1

-3

mV/V

IK=10mA, R1=10kW, R2=open

Note 1

0.15

0.05

0.3

Iref(dev)

IK(min)

Ioff

VKA=Vref

0.3

2.8

0.75

VKA=6V, Vref=0V

VKA=10V, Vref=0V

VKA=15V, Vref=0V

VKA=Vref, f<1 kHz,

IK=0.1 to 15 mA, Note 2

Dynamic impedance

Zka0

0.25

0.4

Note 1: The deviation parameters, Vref(dev) and Iref(dev) are

defined as the differences between the maximum and the minimum

values obtained over the rated temperature range. The average full

range temperature coeficient of the reference input voltage is de-

fined as:

Note 2:

Thedynamic impedance when VKA = Vref is defined as :

æ Vref(dev) ö

´ 10⁶

DVKA

Zka0 =

è Vref(25° C)ø

DT_A

a Vref =

DIK

When the device is operating with two external

resistors (see Figure 2), the total dynamic impedance

of the circuit is given by:

Where:

a Vref unit is ppm/°C

DTA is the rated operating free air temperature

of the device.

R1ö

Zka =

= Zka0 ´ 1+

a Vref can be positive or negative depending on whether

minimum Vref or maximum Vref, respectively occurs at the

lower temperature.

Rev. 1.3

5/10/99

2-6

IRU431L/IRU431AL

PIN DESCRIPTIONS

SOT-23

5-PIN

PIN#

SOT-23

3-PIN

PIN#

8-PIN

SOIC

PIN#

Pin Description

A resistor divider from this pin to the cathode pin and

ground sets the output voltage.

PIN SYMBOL

Ref

The output of the shunt regulator. A minimum of 1mF

capacitor must be connected from this pin to Anode pin

to insure unconditional stability.

Ground pin. This pin must be connected to the lowest

potential in the system and all other pins must be at

higher potential with respect to this pin.

Cathode

Anode

3,6

These pins are not connected internally.

1,2

2,4,5,7

BLOCK DIAGRAM

Cathode

Ref

1.24V

431blk1-1.0

Anode

Figure 1 - Simplified block diagram of the IRU431L

Rev. 1.3

5/10/99

2-7

IRU431L/IRU431AL

The maximum value for the biasing resistor is calcu-

lated using the following equations:

APPLICATION INFORMATION

VMIN - VKA

Output Voltage Setting

RBMAX

IB MAX + ILMAX

IBMAX = IKMIN + IR

Where :

MIN

The IRU431L can be programmed to any voltages in the

range of 1.24 to 6V with the addition of R1 and R2 exter-

nal resistors according to the following formula:

= Minimum supply voltage

ILMAX = Maximum load current

IBMAX = Maximum bias current

IKMIN = Maximum value for the minimum

cathode current spec

Vo = VKA = Vref ´ 1+

+ Iref ´ R1

The IRU431L keeps a constant voltage of 1.240V be-

tween the Ref pin and ground pin. By placing a resistor

R2 across these two pins a constant current flows

through R2, adding to the Iref current and into the R1

resistor producing a voltage equal to the (1.240/R2)*R1

+ Iref * R1 which will be added to the 1.240V to set the

output voltage as shown in the above equation. Since

the input bias current of the Ref pin is 0.5mA max, it

adds a very small error to the output voltage and for most

applications can be ignored. For example, in a typical

5V to 3.3V application where R2=1.21kW and R1=2kW

the error due to the Iadj is only 1mV which is about

0.03% of the nominal set point.

IR = Current through R1

Assuming R1=2kW as before,

3.3 - 1.24

IR =

= 1.03 mA

IBMAX = 0.08 + 1.03 = 1.11 mA

4.5 - 3.3

RB MAX

= 108 W

1.11+10

Selecting RB = 100 W

The maximum power dissipation of the resistor is

calculated under the maximum supply voltage as

follows:

VMAX - VKA

(

)

PRB (MAX) =

KA = V

Where :

IRU431

VMAX = Maximum supply voltage

PRB (MAX) = Maximum RB power dissipation

6 - 3.3

(

)

431app2-1.0

PRB (MAX) =

= 73 mW

100

Thermal Design

The IRU431L is offered in the plastic 8-pin SOIC or the

surface mount SOT23-5 (L) packages. The 8-pin SOIC

package has the maximum power dissipation capability

of 775mW at Ta=25°C with the derating factor of -6.2mW

/ °C.The SOT23-5 package has the maximum power dis-

sipation capability of 150mW at Ta =25°C with the der-

ating factor of -1.2mW / °C.

Figure 2 - Typical application of the

IRU431L for programming the output voltage

Biasing Resistor (RB) Selection

The biasing resistor RB is selected such that it does

not limit the input current under the minimum input

supply and maximum load and biasing current.

An example is given below on how to properly select

the biasing resistor.

Assuming:

VMIN = 4.5 V

VMAX = 6 V

Table below summarizes the maximum power dissipa-

tion capability of each package versus ambient tempera-

ture.

Ambient Temperature (Ta) -°C

Pkg

8-Pin SOIC 775mW 682mW 620mW

558mW 496mW

VKA = 3.3 V

IL = 10mA

SOT23-5 150mW 132mW 120mW

108mW

96mW

Rev. 1.3

5/10/99

2-8

IRU431L/IRU431AL

In our previous example, the maximum power dissipa-

tion of the device is calculated under no load and maxi-

mum input supply condition.

The maximum power is calculated using the following

equation:

æ VMAX - VKA ö

PMAX = VKA ´

Where :

PMAX = Maximum power dissipation of the 431L

For our example :

æ 6 - 3.3ö

PMAX = 3.3 ´

= 89 mW

100

As shown in the power dissipation table, both packages

can handle this power dissipation.

Stability

The IRU431L has many different regions of stability do-

main as a function of the cathode current which are typi-

cal characteristics of the three-terminal shunt regula-

tors. However, in general the device will be unconditionaly

stableforanycathodecurrentifthecapacitor, C O = 1mF

or bigger is connected from cathode to anode pins. If the

cathode current is always kept higher than 3mA under

minimum line and maximum load conditions, the CO can

be cut to 0.01mF and the system will be stable.

Rev. 1.3

5/10/99

2-9

IRU431L/IRU431AL

TYPICAL APPLICATION

I740 Application

OUT

12V

431app3-1.2

Figure 3- Low cost 3.3V to 2.7V output for Intel I740 application.

Ref Desig

C1,2

Description

Shunt Regulator

Capacitor

Resistor

Qty

Part #

Manuf

IRU431L

Elect,220mF,6.3V,ECAOJFQ221 Panasonic

6.2kW, 5%, SMT

Resistor

118W, 1%, SMT

R3,R4

HS1

Resistor

Heat Sink

100W, 1% SMT

Use minimum of 1" square copper pad area

for load current <4A

Rev. 1.3

5/10/99

2-10

IRU431ALCS [INFINEON]

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