A7642E6R [AITSEMI]

DC-DC CONVERTER/BOOST PWM REGULATOR;


型号：	A7642E6R
厂家：	AiT Semiconductor
描述：	DC-DC CONVERTER/BOOST PWM REGULATOR DC-DC转换器
文件：	总9页 (文件大小：315K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

DESCRIPTION

FEATURES

A7642 is an asynchronous PWM boost converter

using a constant frequency peak current mode. An

external Schottky diode is needed. At light load,

A7642 works in the light load mode. The supply

current during the light mode is 100uA , together

with the 200mΩ internal NMOS power transistor

guarantees high efficiency in the whole output load

current range. Up to 2A peak current, Let A7642

can provide 1A output load current, which is

suitable to use as MID and mobile power supply.

The input voltage 3V~25V.The operating frequency

is internally set at 1MHz.



High Efficiency: Up to 92%

1.0MHz Constant Switching Frequency

Switch current up to 2A

Low R_DS(ON): 0.2Ω

Accurate Reference:0.6V

Tiny External Components

Available in SOT-26 Package

APPLICATION



WLED Drivers

Networking cards powered from PCI or PCI-express

slots



MID and Mobile Power

The A7642 is available in SOT-26 package.

TYPICAL APPLICATION

ORDERING INFORMATION

Package Type

SOT-26

Part Number

A7642E6R

A7642E6VR

V: Halogen free Package

R: Tape & Reel

Note

SPQ: 3,000/pcs

AiT provides all RoHS products

Figure 1. Basic Application Circuit with A7642

Suffix ꢀ V ꢀ means Halogen free Package

REV1.0

- JUN 2014 RELEASED -

- 1 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

PIN DESCRIPTION

Top View

Pin #

Symbol

Function

Power Switch Pin. It is the switch node connection to Inductor.

Ground Pin.

GND

Feedback Input Pin. Connect FB to the center point of the

external resistor divider. The feedback threshold voltage is 0.6V.

Chip Shutdown Signal Input. Logic high is normal operation

mode, Logic Low is Shutdown. Don’t leave it floated.

Power Supply Input. Must be closely decoupled to GND, Pin 2,

with a 10μF or greater ceramic capacitor.

SHDN

V_IN

No Internal Connection.

REV1.0

- JUN 2014 RELEASED -

- 2 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

ABSOLUTE MAXIMUM RATINGS

Input Supply Voltage

SW, SHDN Voltage

FB Voltages

-0.3V~+26V

-0.3V~+6V

Package Thermal Resistance^NOTE1

ꢁ_JA

220°C/W

110°C/W

ꢁ_JC

Operating Temperature Range

Storage Temperature Range

Lead Temperature (Soldering, 10s)

-40°C ~+85°C

-65°C~150°C

+260°C

Stress beyond above listed ꢀAbsolute Maximum Ratingsꢂ may lead permanent damage to the device. These are stress ratings only and

operations of the device at these or any other conditions beyond those indicated in the operational sections of the specifications are not

implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

NOTE1: Thermal Resistance is specified with approximately 1 square of 1oz copper.

ELECTRICAL CHARACTERISTICS^NOTE2

V_OUT=12V, T_A= 25°C, Test Circuit of Figure 1, unless otherwise noted.

Parameter

Input Voltage Range

Symbol

V_IN

Conditions

Min.

Typ. Max.

Unit

Quiescent Current

I_Q

FB=0.66V,No switch

SHDN=0

100

μA

mΩ

Shutdown Current

I_SHDN

R_DS(ON)

Low Side Main FET RON

Main FET Current Limit

Switching Frequency

Feedback Reference Voltage

IN UVLO rising threshold

UVLO hysteresis

200

2.6

LIM1

F_SW

V_REF

V_IN=3V,I_O=300mA

V_IN=3V,I_O=10mA

V_INRising

0.8

1.2

0.612

2.7

MHz

0.588

0.6

V_UVLO

UVLO._HYS

T_SD

0.1

Thermal Shutdown Temperature

150

°C

NOTE2: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.

REV1.0

- JUN 2014 RELEASED -

- 3 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

TYPICAL PERFORMANCE CHARACTERISTICS

ꢃ vs. I_O(V_O=24V)

Imax vs. V_IN(V_O=12V)

ꢃ vs. I_O(V_O=12V)

REV1.0

- JUN 2014 RELEASED -

- 4 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

BLOCK DIAGRAM

REV1.0

- JUN 2014 RELEASED -

- 5 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

DETAILED INFORMATION

Operation

The A7642 uses a fixed frequency, peak current mode boost regulator architecture to regulate voltage at the

feedback pin. The operation of the A7642 can be understood by referring to the block diagram of BLOCK

DIAGRAM. At the start of each oscillator cycle the MOSFET is turned on through the control circuitry. To

prevent subharmonic oscillations at duty cycles greater than 50 percent, a stabilizing ramp is added to the

output of the current sense amplifier and the result is fed into the negative input of the PWM comparator.

When this voltage equals the output voltage of the error amplifier the power MOSFET is turned off. The

voltage at the output of the error amplifier is an amplified version of the difference between the 0.6V bandgap

reference voltage and the feedback voltage. In this way the peak current level keeps the output in regulation.

If the feedback voltage starts to drop, the output of the error amplifier increases. These results in more current

to flow through the power MOSFET, thus increasing the power delivered to the output. The A7642 has

internal soft start to limit the amount of input current at startup and to also limit the amount of overshoot on the

output.

Application Information

Setting the Output Voltage

The internal reference V_REFis 0.6V (Typical).The output voltage is divided by a resistor divider, R1 and R2 to

the FB pin. The output voltage is given by

Inductor Selection

The recommended values of inductor are 3.3 to 10μH. Small size and better efficiency are the major concerns

for portable device, such as A7642 used for mobile phone. The inductor should have low core loss at 1.0MHz

and low DCR for better efficiency. To avoid inductor saturation current rating should be considered.

Capacitor Selection

Input ceramic capacitor of 10μF is recommended for A7642 applications. For better voltage filtering, ceramic

capacitors with low ESR are recommended. X5R and X7R types are suitable because of their wider voltage

and temperature ranges.

REV1.0

- JUN 2014 RELEASED -

- 6 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

Diode Selection

Schottky diode is a good choice for A7642 because of its low forward voltage drop and fast reverses recovery.

Using Schottky diode can get better efficiency. The high speed rectification is also a good characteristic of

Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of

the peak current and output average current multiplication as following:

The diode’ s reverse breakdown voltage should be larger than the output voltage.

Layout Consideration

For best performance of the A7642, the following guidelines must be strictly followed.



Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce

noise coupling.



The GND should be connected to a strong ground plane for heat sinking and noise protection.

Keep the main current traces as possible as short and wide.

SW node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area.

Place the feedback components as close as possible to the IC and keep away from the noisy device

REV1.0

- JUN 2014 RELEASED -

- 7 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

PACKAGE INFORMATION

Dimension in SOT-26 Package (Unit: mm)

SYMBOL

MIN

MAX

1.050

0.000

1.050

0.300

0.100

2.820

1.500

2.650

1.250

0.100

1.150

0.500

0.200

3.020

1.700

2.950

0.950(BSC)

1.800

0.300

0°

2.000

0.600

8°

ꢁ

REV1.0

- JUN 2014 RELEASED -

- 8 -

A7642

DC-DC CONVERTER/BOOST (STEP-UP)

1MHz, 2A PWM REGULATOR

AiT Semiconductor Inc.

www.ait-ic.com

IMPORTANT NOTICE

AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to

discontinue any integrated circuit product or service without notice, and advises its customers to obtain the

latest version of relevant information to verify, before placing orders, that the information being relied on is

current.

AiT Semiconductor Inc.'s integrated circuit products are not designed, intended, authorized, or warranted to

be suitable for use in life support applications, devices or systems or other critical applications. Use of AiT

products in such applications is understood to be fully at the risk of the customer. As used herein may involve

potential risks of death, personal injury, or servere property, or environmental damage. In order to minimize

risks associated with the customer's applications, the customer should provide adequate design and

operating safeguards.

AiT Semiconductor Inc. assumes to no liability to customer product design or application support. AiT

warrants the performance of its products of the specifications applicable at the time of sale.

REV1.0

- JUN 2014 RELEASED -

- 9 -

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