WT1117AD-30 [WEITRON]

1.0A LOW DROPOUT PRECISION LINEAR REGULATORS; 1.0A低压差精密线性稳压器


型号：	WT1117AD-30
厂家：	WEITRON TECHNOLOGY
描述：	1.0A LOW DROPOUT PRECISION LINEAR REGULATORS 1.0A低压差精密线性稳压器稳压器
文件：	总11页 (文件大小：627K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

WEITRON

WT1117A

1.0A LOW DROPOUT PRECISION LINEAR REGULATORS

P b

Lead(Pb)-Free

General Description:

WT1117A of positive adjustable and fixed regulators is designed to provide 1.0A output with

low dropout voltage performance. On-chip trimming adjusts the reference voltage to 1.5%.

For usage on working in post regulators or microprocessor power supplies, low voltage

operation and fast transient response are required.

WT1117A is available in surface-mount SOT-223 and TO-252 packages.

Features:

* Adjustable or Fixed Output

* Output Current of 1.0A

* Dropout Voltage(Typical) 1.15V @1.0A

* Line Regulation 0.2% max.

* Load Regulation 0.4% max.

* Fast Transient Response

* Current Limit Protection

* Thermal Shutdown Protection

Applications:

* High Eﬃciency Linear Regulators

* Post Regulators for Switching Supplies

* Microprocessor Supply

* Hard Drive Controllers

* Battery Chargers

* Adjustable Power Supply

WEITRON

hpp://www.weitron.com.tw

1/11

Rev-A 18-Oct-06

WT1117A

Ordering Information

Ordering Number Output Voltage Package

Shipping

2,500 Units/Tape&Reel

WT1117AN-X

WT1117AD-X

WT1117AN-15

SOT-223

TO-252

Adj

1.5

SOT-223 2,500 Units/Tape&Reel

2,500 Units/Tape&Reel

TO-252

SOT-223

TO-252

SOT-223

TO-252

SOT-223

TO-252

SOT-223

TO-252

SOT-223

TO-252

SOT-223

TO-252

WT1117AD-15

WT1117AN-18

WT1117AD-18

WT1117AN-25

1.8

2.5

2,500 Units/Tape&Reel

WT1117AD-25

WT1117AN-285

WT1117AD-285

2.5

2.85

3.0

2,500 Units/Tape&Reel

WT1117AN-30

WT1117AD-30

WT1117AN-33

3.0

3.3

2,500 Units/Tape&Reel

WT1117AD-33

WT1117AN-50

WT1117AD-50

3.3

5.0

Marking Information & PIN Configurtions (Top View)

TO-252 (DPAK)

SOT-223

1117-VV

YAWW

1117-VV

YAWW

V_IN

V_OUT

ADJ/GND*

ADJ/ GND*

)

On fixed versions Pin 1 = GND,

on adjustable versions Pin 1 = ADJ

V V/VVV = Output Voltage (50 = 5.0V, 285= 2.85V ,X = ADJ

= Assembly Location

= Year

Tab = V

OUT

W W

= Weekly

WEITRON

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2/11

Rev-A 18-Oct-06

WT1117A

Typical Application

(Fixed Version)

(Adjustable Version)

WT1117A-3.3

WT1117A-Adj

> 4.75V

V > 4.75V

= 3.45V

= 3.3V

OUT

133

1.0%

GND

ADJ

10μF

Tant

10μF

Tant.Min

10μF

Tant

10μF

Tant.Min

232

1.0%

= V

X (1 +

) + I

X R2

OUT

REF

ADJ

Notes:

1. C1 needed if device is far from filter capacitors

2. C2 minimum value required for stability

Block Diagram

(Fixed Version)

OUT

Output

Current

Limit

Thermal

Shutdown

Error

Amplifier

Bandgap

Reference

GND

(Adjustable Version)

OUT

Output

Current

Limit

Thermal

Shutdown

Error

Amplifier

Bandgap

Reference

ADJ

WEITRON

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3/11

Rev-A 18-Oct-06

WT1117A

Parameter

Power Dissipation

Symbol

Value

UNIT

Internally limited

P_D

V_IN

Input Voltage

7.0

T_LEAD

Lead Temperature(Soldering, 10sec)

300

°C

Operating Junction Temperature Range

Control Section

Power Transistor

T_J

-40 to 125

-40 to 150

°C

T_STG

Storage Temperature Range

-65 to + 150

Thermal Characteristics

SOT-223

Thermal Resistance, Junction-to-Case

DPAK

°C/ W

6.0

Thermal Resistance, Junction-to-Case

WEITRON

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Rev-A 18-Oct-06

4/11

WT1117A

ELECTRICAL CHARACTERISTICS

Typicals and limits appearing in normal type apply for Tj 25°C

Symbol

Typ

Parameter

Condition

Min

Max Unit

I_OUT=10mA, V_IN= 5V

1.232 1.250 1.268

1.225 1.250 1.275

Reference Voltage

WT1117A-Adj

REF

10mA I_OUT1.0A, 2.65V V_IN7V

I_OUT=10mA, V_IN=V

+1.5V

+1.5

-1.5

OUT

Output Voltage

Line Regulation

Load Regulation

V_IN=V

+1.5V to 7 V

OUT

-2

I_OUT1.0A

I_Load=10mA,

REG

All

0.04

0.20

0.40

LINE

(1.5 V +V

OUT

)

OUT

+ 1.5V

OUT

REG

0.20

LOAD

I_Load=10mA to 1.0A

=1.0A

OUT

Dropout Voltage

Current Limit

All

1.15

1.3

V -V

=1.5V

All

1.0

IN OUT

V =5V, Vadj=0V

Minimum Load Current

WT1117A-Adj

O MIN

+ 1.5V

OUT

All Fixed

Versions

Ground Current

I_Load=10mA to 1.0A

I_Load=10mA, 2.65V

Adjust Pin Current

Temp. Coefficient

Thermal Regulation

Ripple Rejection (Note 1)

WT1117A-Adj

0.005

0.003

μA

%/°C

%/W

ADJ

V -V

=1.5V, I_Load=10mA

All

IN OUT

T =25℃, 30ms pulse

V -V

=1.5V, I_Load=1.0A

IN OUT

Note 1: 120Hz input ripple (C_ADJfor ADJ =25μF)

WEITRON

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5/11

Rev-A 18-Oct-06

WT1117A

Typical Performance Characteristics

1.00

0.10

0.08

0.06

0.04

0.02

0.00

-0.02

-0.04

-0.06

-0.08

-0.10

-0.12

T_CASE= 0°C

0.95

T_CASE= 25°C

0.90

0.85

T_CASE= 125°C

0.80

0.75

10 20 30 40 50 60 70 80 90 100 110 120 130

200

400

600

800

1000

I_OUT(mA)

T_J(°C)

Fig.1 Dropout Voltage vs. Output Current

Fig.2 Reference Voltage vs. Temperature

I_O= 10mA

_CASE= 25°C

I_OUT= 1.0A

(V -V ) = 3.0V

IN OUT

= 1.0VP-P

RIPPLE

C_adj=0.1μF

10¹10²

10³

10⁴

10⁵

10⁶

10 20 30 40 50 60 70 80 90 100 110 120 130

Frequency(Hz)

Temperature (°C)

Fig.4 Ripple Rejection vs. Frequency

Fig.3 Adjust Pin Current vs. Temperature

3.5

3.3

3.1

2.9

2.7

2.5

2.3

2.1

1.9

1.7

1.5

300

200

100

V_OUT= 3.3V

_OUT= C_IN=22μF Tantalum

C_Adj=0.1μF

-100

-200

1000

500

1.0

1.5

2.0

2.5

3.0

3.5

4.0

V_IN- V_OUT(V)

Tim(μS)

Fig.5 Transient Response

Fig.6 Short Circuit Current vs. V - V

OUT

WEITRON

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Rev-A 18-Oct-06

6/11

WT1117A

APPLICATION INFORMATION

WT1117A linear regulators provide fixed and adjustable output voltages at currents up to 1.0A. These regulators

are protected against overcurrent conditions and include thermal shutdown protection. The WT1117A's have

a composite PNP-NPN output transistorand require an output capacitor for stability. A detailed procedure for

selecting this capacitor follows.

Adjustable Operation

The WT1117A has an output voltage range of 1.25 V to 5.5 V. An external resistor divider sets the output voltage

as shown in Figure 1. The regulator maintains a fixed 1.25V (typical) reference between the output pin and the

adjust pin.

A resistor divider network R1 and R2 causes a fixed current to flow to ground. This current creates a voltage

across R2 that adds to the 1.25V across R1 and sets the overall output voltage. The adjust pin current

(typically 35μA) also flows through R2 and adds a small error that should be taken into account if precise

adjustment of V

is necessary.

OUT

The output voltage is set according to the formula:

R1 + R2

= V

X (

) + I

X R2

OUT

REF

Adj

The term IAdj R2 represents the error added by the adjust pin current.

R1 is chosen so that the minimum load current is at least 2.0mA R1 and R2 should be the same type e.g.

metal film for best tracking over temperature. While not required, a bypass capacitor from the adjust pin to ground

will improve ripple rejection and transient response. A 0.1μF tantalum capacitor is recommended for first

cut design. Type and value may be varied to obtainoptimum performance vs. price.

WT1117A

OUT

Adj

REF

Adj

Figure1. Resistor Divider Scheme

Stability Considerations

The output compensation capacitor helps to determine three main characteristics of a linear regulator’s performance:

start-up delay,load transient response, and loop stability. The capacitor value and type is based on cost, availability,

size and temperature constrains, A tantalum or aluminum electrolytic capacitor is preferred, as a ﬁlm or ceramic

capacitor with almost zero ESR can cause Instability. An aluminum electrolytic capacitor is the least expensive type.

but when the circuit operates at low temperatures, both the value and ESR of the capacitor will vary widelt.For optimum

performance over the full operating temperature range, a tantalum capacitor is best, A 22µF tantalum capacitor will work

ﬁne in most applications, but with high current regulators such as the WT1117A higher capacitance values will improve

the transient response and stability. Most applications for the WT1117A’s involve large changes in load current, so the

output capacitor must supply instantaneous load current. The ESR of the output capacitor causes an immediate drop

in output voltage given by:

V = I x ESR

In microprocessor applications an output capacitor network of several tantalum and ceramic capacitors in parallel is

commonly used. This reduces overall ESR and minimizes the instantaneous output voltage drop under transient load

conditions. The output capacitor network should be placed as close to the load as possible for the best results.

Used with large output capacitance values and theinput voltage is instantaneously shorted to ground, damage can occur.

In this case, a diode connected as shown above in Figure1.

WEITRON

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Rev-A 18-Oct-06

7/11

WT1117A

Protection Diodes

When large external capacitors are used with most linear regulator, it is wise to add protection diodes. If the input voltage

of the regulator is shorted, the output capacitor will discharge into the output of the regulator. The discharge current

depends on the value of capacitor, output voltage, and rate at which V drops.

Figure2 ^(a),(b)Protection Diode Scheme for Large Output Capacitors

(a) Fixed Version

(b) Adjustable Version

IN4002

V_IN

V_OUT

V_IN

V_OUT

V_IN

V_OUT

V_IN

V_OUT

WT1117A-Adj

WT1117A-3.3

ADJ

GND

C_ADJ

In the WT1117A linear regulators, the discharge path is through a large junction, and protection diodes are normally not

needed. However, damage can occur if the regulator is used with large output capacitance values and the input voltage

is instantaneously shorted to ground. In this case, a diode connected as shown above in Figure 2.

Output Voltage Sensing

The WT1117A are three terminal regulators. For which, they cannot provide true remote load sensing. Load regulation

is limited by the resistance of the conductors connecting the regulator to the load. For best results the WT1117A

should be connected are as shown in Figure 3.

Figure3 ^(a),(b)Conductor Parasitic Resistance Effects are Minimized by this Grounding Scheme For Fixed and Adjustable Output Regulators

Conductor

Parasitic

Resistance

Conductor

Parasitic

Resistance

V_IN

WT1117A-Adj

R_C

V_OUT

V_IN

WT1117A-3.3

GND

V_IN

V_OUT

R_LOAD

(a) Fixed Version

(b) Adjustable Version

Calculating Power Dissipation and Heat Sink Requirements

The WT1117A precision linear regulators include thermal shutdown and current limit circuitry to protect the devices.

However, high power regulators normally operate at high junction temperatures. It is important to calculate the power

dissipation and junction temperatures accurately to be sure that you use and adequate heat sink. The case is connected

to V

on the WT1117A, and electrical isolation may be required for some applications. Thermal compound should always

OUT

be used with high current regulators like the WT1117A.

WEITRON

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Rev-A 18-Oct-06

8/11

WT1117A

The thermal characteristics of an IC depend four factors:

1. Maximum Ambient Temperature T (°C)

2. Power Dissipation P (Watts)

3. Maximum Junction Junction Temperature T (°C)

4. Thermal Resistance Junction to ambient R (°C/W)

θJA

The relationship of these four factors is expressed by equation (1):

T =T + P X R

θJA

........(1)

Maximum ambient temperature and power dissipation are determined by the design while the maximum junction

temperature and thermal resistance depend on the manufacturer and the package type.

The maximum power dissipation for a regulator is expressed by equation (2):

P_D(max)= { V_IN(max)- V_OUT(min)} I_OUT(max₎+ V_IN(max)I_Q........(2)

where:

is the maximum input voltage,

is the minimum output voltage,

is the maximum output current

IN(max)

OUT(min)

OUT(max)

I is the maximum quiescent current at I

OUT(max)

A heat sink eﬀectively increases the surface area of the package to improve the ﬂow of heat away from the IC into the air.

Each material in the heat ﬂow path between the IC and the environment has a thermal resistance. Like series electrical

resistances, these resistance are summed to determine R the total thermal resistance between the junction and the air.

θJA

This is expressed by equation (3):

+ R

X R

θSA

........(3)

θJA

θJC

θCS

Where all of the following are in °C/W

θJC

θCS

θSA

is thermal resistance of junction to case,

is thermal resistance of case to heat sink,

is thermal resistance of heat sink to ambient air

The value for R is calculated using equation (3) and the result can be substituted in equation (1) .The value for R is

θJA

θJC

3.5°C/W for a given package type based on an average die size. For a high current regulator such as the WT1117A the

majority of the heat is generated in the power transistor section.

WEITRON

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Rev-A 18-Oct-06

9/11

WT1117A

TO-252-3 PACKAGE OUTLINE DIMENSIONS

6.50 0.10

5.30 0.10

2.30 0.10

0.51 0.005

1.40 0.10

5.50 0.10

9.50 0.25

1.00 0.10

0.80 0.05

1.20 0.25

0.51 0.05

2.30 0.05

0.60 0.05

4.60 0.10

Unit: mm

SOT-223 PACKAGE OUTLINE DIMENSIONS

6.50 0.20

3.00 0.10

0.325 0.005

3.50 0.15

7.00 0.15

1.75TYP

0~10

2.30 0.05

4.60 0.10

0.73 0.05

1.60 0.05

0.06 0.04

Unit: mm

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Rev-A 18-Oct-06

10/11

WT1117A

ORDERING NUMBER

WT1117 AX - XX

Output Voltage

- X : Adj

- 15 : 1.5V

- 18 : 1.8V

- 25 : 2.5V

- 285 : 2.85V

- 30 : 3.0V

- 33 : 3.3V

- 50 : 5.0V

Circuit Type

Output Current = 1.0A

Package

N : SOT-223

D : TO-252

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Rev-A 18-Oct-06

11/11

WT1117AD-30 [WEITRON]

相关型号：

WT1117AD-33

WT1117AD-50

WT1117AD-X

WT1117AN-15

WT1117AN-18

WT1117AN-25

WT1117AN-285

WT1117AN-30

WT1117AN-33

WT1117AN-50

WT1117AN-X

WT11I-A