G5E1284-XX [ETL]

4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator;


型号：	G5E1284-XX
厂家：	E-TECH ELECTRONICS LTD
描述：	4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
文件：	总4页 (文件大小：217K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

ISSUED DATE :2005/05/24

REVISED DATE :2006/03/29B

GTM

CORPORATION

G5E1284

4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator

Description

The G5E1284 is 4A regulator with extremely low dropout voltage. This product is specifically designed to

provide well regulated supply for applications requiring 2.8V or lower voltages from 3.3V ATX power supplies

where high efficiency of the switch can be achieved without the cost and complexity associated with switching

regulator. One such application is the new graphic chipsets that requires anywhere from 2.4V to 2.7V supply.

Features

Ԧ0.7V maximum dropout voltage at 4A load current

ԦBuilt-in thermal shutdown

ԦOutput current limiting

ԦAdjustable or fixed output voltage 1.5V,1.8V,2.5V,3.3V,5.0V

ԦFast transient response

ԦGood noise rejection

Package Dimensions

Millimeter

REF.

Min.

Max.

4.80

1.00

0.50

9.00

10.4

15.3

Min.

6.20

1.25

Max.

6.60

1.45

4.40

0.76

0.36

8.60

9.80

14.7

13.25

14.25

1.70 REF.

2.60

3.71

2.89

3.96

Typical Application

Block Diagram

G5E1284-25

Pin Descriptions

Name

I/O

Description

Adj (Gnd)

A resistor divider from this pin to the Vout pin and ground sets the output voltage. (Gnd only for fixed mode)

The pin is the positive side of the reference that allows remote load sensing to achieve excellent load

regulation. A minimum of 10uF capacitor must be connected from this pin to ground to insure stability.

Vsense

The input pin of regulator. Typically a large storage capacitor is connected from this pin to ground to insure

that the input voltage does not sag below the minimum dropout voltage during the load transient response.

This pin must always be higher than Vout in order for the device to regulate.

Vin

This pin is the supply pin for the internal control circuit as well as the base drive for the pass transistor. This

pin must always by higher than the Vout pin in order the device to regulate. A minimum of 100uF capacitor

must be connected from this pin to ground to insure stability.

Vctrl

Vout

The output of the regulator. A minimum of 100uF capacitor must be connected from this pin to ground to

insure stability.

G5E1284

Page: 1/4

ISSUED DATE :2005/05/24

REVISED DATE :2006/03/29B

GTM

CORPORATION

Absolute Maximum Ratings

Symbol

Parameter

Ratings

Unit

Input Voltage

ctrl

Control Input Voltage

Power Dissipation (with heat sink or amount of copper board needed.)

Storage Temperature Range

2.4 ~ 4.4

-65 ~ + 150

0 ~ + 150

Operating Junction Temperature Range

Electrical Characteristics Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, T

=0~150к.

Typical value refer to TJ =25к. Vout=Vsense

Parameter

Conditions

MIN

TYP

1.250

1.500

1.800

2.500

3.300

5.000

MAX

1.275

1.530

1.836

2.550

3.365

5.100

0.2

UNIT

Reference Voltage

Output Voltage

Line Regulator

G5E1284-ADJ

G5E1284-15

G5E1284-18

G5E1284-25

G5E1284-33

G5E1284-50

G5E1284-XX

o=10mA, T

=25к, (Vin-Vout)=0.7V, Vctrl=Vin+1V

=25к, 2.2V≤Vin≤12V, Vctrl=Vin+1V

=25к, 2.5V≤Vin≤12V, Vctrl=Vin+1V

=25к, 3.2V≤Vin≤12V, Vctrl=Vin+1V

=25к, 4.0V≤Vin≤12V, Vctrl=Vin+1V

=25к, 5.7V≤Vin≤12V, Vctrl=Vin+1V

=25к, Vout+0.7<Vin<12, Vctrl=Vin+1V

1.225

1.470

1.764

2.450

3.235

4.900

G5E1284-ADJ (Vin-Vout)=2V, 0mA<

Io<4A, T

=25к, Vctrl=Vin+1V

G5E1284-15

G5E1284-18

G5E1284-25

G5E1284-33

G5E1284-50

Vin=3.0V, 0mA<

Vin=3.3V, 0mA<

Vin=4.0V, 0mA<

Vin=5.0V, 0mA<

Vin=8.0V, 0mA<

o<4A, T

=25к, Vctrl=4V

=25к, Vctrl=4.3V

=25к, Vctrl=5V

=25к, Vctrl=6V

=25к, Vctrl=9V

Load Regulation

Vadj=0V, for all conditions below. (∆Vout=1%Vout)

Vin=2.05V,

o=1.5A

o=3.0A

o=4.0A

o=4.0A (∆Vout=1%Vout)

Vadj=0V, for all conditions below. (∆Vout=1%Vout)

1.15

1.18

1.25

G5E1284-ADJ

(fixed model)

G5E1284-ADJ

Dropout Voltage

(Vctrl-Vout)

1.10

Vin= Vout +0.8V,

1.25

Vctrl=2.75V, o=1.5A

Vctrl=2.75V, o=3.0A

Vctrl=2.75V, o=4.0A

Vctrl=3.3V, Io=4.0A (∆Vout=1%Vout)

0.26

0.50

0.70

0.38

0.60

0.85

Dropout Voltage

(Vin-Vout)

G5E1284-15

G5E1284-18

G5E1284-25

G5E1284-33

G5E1284-50

0.70

0.85

Vctrl=Vout +1.5V, Io=4.0A (∆Vout=1%Vout)

Current Limit

Vctrl=2.75V, Vin=2.05V, ∆Vo=100mV, Vadj=0V

4.2

0.02

Minimum Load Current Vctrl=5V, Vin=3.3V, Vadj=0V

%/W

Thermal Regulation

Ripple Rejection

30ms pulse

0.01

Vctrl=5V, Vin=5V,

Io=4.0A, Vadj=0V, T

=25к, Vripple=1Vpp at 120Hz

Vadj=0V, for all conditions below.

Vctrl=2.75V, Vin=2.05V,

o=1.5A

o=3.0A

o=4.0A

G5E1284-ADJ

G5E1284-15

G5E1284-18

G5E1284-25

G5E1284-33

G5E1284-50

Vctrl=3.3V, Vin=2.3V, I

Control Pin Current

Vctrl= Vout +1.5V, Vin= Vout +0.8V, Io=4.0A

Adjust Pin Current

Quiescent Current

Vctrl=2.75V, Vin=2.05V,

Vctrl=13V, Vin=12V, o=10mA (fixed model)

Control Circuitry/Power Transistor

o=10mA, Vadj=0

150

Thermal Resistance

Junction-to-Case

2.5

к/W

Note 1: G5E1284-ADJ incorporates an internal thermal shutdown that protects the device where the junction temperature exceeds the

allowable maximum junction temperature.

G5E1284

Page: 2/4

ISSUED DATE :2005/05/24

REVISED DATE :2006/03/29B

GTM

CORPORATION

Functional Description

Introduction

The G5E1284 regulator is 5-terminal device designed specifically to provide extremely low dropout voltage comparable to

the PNP type without the disadvantage of the extra power dissipation due to the base current associated with PNP

regulators. This is done by bringing out the control pin of the regulator that provides the base current to the power NPN and

connecting it to a voltage that is greater than the voltage present at the Vin pin. This flexibility makes the G5E1284 ideal for

applications where dual inputs are available such as a computer motherboard with an ATX style power supply that provides

5V and 3.3V to the board. One such application is the new graphic chip sets that require anywhere from 2.4V to 2.7V

supply. The G5E1284 can easily be programmed with the addition of two external resistors to any voltages within the range

of 1.25V to 15.5V. Another major requirement of these graphic chips is the need to switch the load current from zero to

several amps in tens of nanoseconds at the processor pins, which translates to an approximately 300 to 500ns of current

step at the regulator. In addition, the output voltage tolerances are also extremely tight and they include the transient

response as part of the specification.

The G5E1284 is specifically designed to meet the fast current transient needs as well as providing an accurate initial

voltage, reducing the overall system cost with the need for fewer number of output capacitors. Another feature of the device

is its true remote sensing capability that allows accurate voltage setting at the load rather than at the device.

Output Voltage Setting

The G5E1284 can be programmed to any voltage in the range of 1.25V to 15.5V with the addition of R1 and R2 external

resistors according to the following formula:

G5E1284-ADJ

The G5E1284-ADJ keeps a constant 1.25V between the Vsense pin and the Adj pin. By placing a resistor R1 across these

two pins and connecting the Vsense and Vout pin together, a constant current flows through R1, adding to the Iadj current

and into the R2 resistor producing a voltage equal to the (1.25/R1)*R2+Iadj*R2. This voltage is then added to the 1.25V to

set the output voltage. This is summarized in the above equation. Since the minimum load current requirement of the

G5E1284-adj is 10mA, R1 is typically selected to be 121ꢀ resistor so that it automatically satisfies this condition. Notice

that since Iadj is typically in the range of 55uA it only adds a small error to the output voltage and should only be

considered when a very precise output voltage setting is required.

Load Regulation

Since the G5E1284 has separate pins for the output (Vout) and the sense (Vsense), it is ideal for providing true remote

sensing of output voltage at the load. This means that the voltage drops due to parasitic resistance such PCB traces

between the regulator and the load are compensated for using remote sensing. Figure following shows a typical application

of the G5E1284-ADJ with remote sensing.

G5E1284-ADJ

Stability

The G5E1284-XX requires the use of an output capacitor as part of the frequency compensation in order to make the

regulator stable. Typical designs for the microprocessor application use standard electrolytic with typical ESR in the range

of 50 to 100mꢀ and an output capacitance of 100uF to 1000uF. Fortunately as the capacitance increases, the ESR

decreases resulting in a fixed RC time constant. The G5E1284-XX takes advantage of the phenomena in making the

overall regulator loop stable. For most applications a minimum of 100uF aluminum electrolytic capacitor insures both

stability and good transient response.

Thermal Design

The G5E1284-XX incorporates an internal thermal shutdown that protects the device when the junction temperature

exceeds the maximum allowable junction temperatures. Although this device can operate with junction temperatures in the

range of 150к, it is recommended that the selected heat sink be chosen such that during maximum continuous load

operation, the junction temperature is kept below this number.

G5E1284

Page: 3/4

ISSUED DATE :2005/05/24

REVISED DATE :2006/03/29B

GTM

CORPORATION

Performance Characteristics

Important Notice:

All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM.

GTM reserves the right to make changes to its products without notice.

GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems.

GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance.

Head Office And Factory:

Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C.

TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785

China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China

TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165

G5E1284

Page: 4/4

G5E1284-XX [ETL]

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