A7407E6R [AITSEMI]

DC-DC CONVERTER/ BUCK INPUT STANDOFF VOLTAGE STEP-DOWN CONVERTER;


型号：	A7407E6R
厂家：	AiT Semiconductor
描述：	DC-DC CONVERTER/ BUCK INPUT STANDOFF VOLTAGE STEP-DOWN CONVERTER DC-DC转换器输入元件
文件：	总11页 (文件大小：354K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

DESCRIPTION

FEATURES

The A7407 is a wide input range, high-efficiency, and

high frequency DC-to-DC step-down switching

regulator, capable of delivering up to 0.7A of output

current. With a fixed switching frequency of 660KHz,

this current mode PWM controlled converter allows

the use of small external components, such as

ceramic input and output caps, as well as small

inductors. A7407 also employs a proprietary control

scheme that switches the device into a power save

mode during light load, thereby extending the range

of high efficiency operation. An OVP function protects

the IC itself and its downstream system against input

voltage surges. With this OVP function, the IC can

stand off input voltage as high as 42V, making it an

ideal solution for industrial applications such as smart

meters as well as automotive applications.

In automotive systems, power comes from the

battery, with its voltage typically between 9V and 24V.

Including cold crank and double battery jump-starts,

the minimum input voltage may be as low as 4V and

the maximum up to 36V, with even higher transient

voltages. With these high input voltages, linear

regulators cannot be used for high supply currents

without overheating the regulator. Instead, high

efficiency switching regulators such as A7407 must

be used to minimize thermal dissipation.



Wide Input Operating Range from 4V to 38V

Standoff Input Voltage: 42V

High Efficiency at 12V In 5V Out: Up to 92%:

High Efficiency PFM mode at light load

Capable of Delivering 0.7A

No External Compensation Needed

Current Mode control

Logic Control Shutdown

Thermal shutdown and UVLO

Available in SOT-26 Package

APPLICATION



Smart Meters

Industrial Applications

Automotive Applications

TYPICAL APPLICATION

The A7407 is available in SOT-26 package.

ORDERING INFORMATION

Package Type

SOT-26

Part Number

A7407E6R

A7407E6VR

V: Halogen free Package

R: Tape & Reel

Note

AiT provides all RoHS products

Suffix “ V “ means Halogen free Package

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 1 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

PIN DESCRIPTION

Top View

Pin #

Symbol

BST

Function

Bootstrap pin. Connect a 10nF capacitor from this pin to SW

Ground

GND

Feedback Input. Connect an external resistor divider from the output to

FB and GND to set V_OUT

Enable pin for the IC. Drive this pin high to enable the part, low to disable.

Supply Voltage. Bypass with a 10μF ceramic capacitor to GND

Inductor Connection. Connect an inductor Between SW and the regulator

output.

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 2 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

ABSOLUTE MAXIMUM RATINGS

Input Voltage Range

-0.3V~42V

150°C

Max Operating Junction Temperature(Tj)

SW, EN Voltage

-0.3V~ V_IN+0.3V

-0.3V ~ SW+6V

-0.3V ~ 6V

BST Voltage

FB Voltage

SW to ground current

Internally limited

-40°C ~85°C

110°C/W

T_J, Operating Junction Temperature

θ_JC, Package Thermal Resistance

T_S, Storage Temperature

-55°C~150°C

Stress beyond above listed “Absolute Maximum Ratings” 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.

ELECTRICAL CHARACTERISTICS

V_IN= 12V, unless otherwise specified. Typical values are at T_A= 25°C.

Parameter

Input Standoff Voltage

Input Voltage Range

Input UVLO

Conditions

Min.

Typ.

Max.

Unit

Rising, Hysteresis=140mV

Rising, Hysteresis=1.3V

V_FB=0.85V

3.8

Input OVP

Input Supply Current

Input Shutdown Current

FB Feedback Voltage

FB Input Current

0.6

μA

0.8

0.01

660

μA

KHz

Switching Frequency

Maximum Duty Cycle

FoldBack Frequency

High side Switch On Resistance

High side Switch Current Limit

SW Leakage Current

EN Input Current

V_FB= 0V

400

1.2

KHz

mΩ

I_SW=200mA

V_IN=12V,V_SW=0, EN= GND

V_IN=12V ,V_EN=5V

μA

EN Input Low Voltage

Thermal Shutdown

Rising, Hysteresis=100mV

Hysteresis=40°C

0.8

1.1

150

1.4

°C

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 3 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

TYPICAL PERFORMANCE CHARACTERISTICS

Typical values are at T_A=25°C, unless otherwise specified.

Efficiency vs. I_OUT

3. I_Qvs. V_IN

4. V_OUTvs. I_OUT

5. V_OUTvs. V_IN

6. V_OUTvs. Temperature

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 4 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

Start-up Waveform with EN

V_IN=12V,V_OUT=5V,I_OUT=0A

Frequency vs. Temperature

Start-up Waveform with EN=V_IN

V_IN=12V,V_OUT=5V,I_OUT=0A

10. Shutdown Waveform with EN

V_IN=30V,V_OUT=5V,I_OUT=0.5A

11. Switching Waveform

V_IN=12V,V_OUT=5V,I_OUT=0.1A

12. Switching Waveform

V_IN=12V,V_OUT=5V,I_OUT=0.3A

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 5 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

13. Load Transient Response

14. Load Transient Response

V_IN=12V,V_OUT=5V,I_OUT=0 to 0.5A

V_IN=12V,V_OUT=3.3V,I_OUT=0 to 0.5A

15. Short-Circuit Response

16. Short-Circuit Recovery

V_IN=24V,V_OUT=5V,I_OUT=0 to Short

V_IN=24V,V_OUT=5V,I_OUT= Short to 0A

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 6 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

BLOCK DIAGRAM

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 7 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

DETAILED INFORMATION

Functional Descriptions

Loop Operation

The A7407 is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of

delivering up to 0.7A of output current, integrated with a 400mΩ high side MOSFET. It uses a PWM

current-mode control scheme. An error amplifier integrates error between the FB signal and the internal

reference voltage. The output of the integrator is then compared to the sum of a current-sense signal and the

slope compensation ramp. This operation generates a PWM signal that modulates the duty cycle of the power

MOSFETs to achieve regulation for output voltage.

Light Load Operation

Traditionally, a fixed constant frequency PWM DC-DC regulator always switches even when the output load is

small. When energy is shuffling back and forth through the power MOSFETs, power is lost due to the finite

RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss is prominent and efficiency is

therefore very low. A7407 employs a proprietary control scheme that improves efficiency in this situation by

enabling the device into a power save mode during light load, thereby extending the range of high efficiency

operation.

Application Information

Setting Output Voltages

Output voltages are set by external resistors. The FB threshold is 0.8V.

_TOP= R_BOTTOMx [(V_OUT/ 0.8) - 1]

Inductor Selection

The peak-to-peak ripple is limited to 30% of the maximum output current. This places the peak current far

enough from the minimum over current trip level to ensure reliable operation while providing enough current

ripples for the current mode converter to operate stably. In this case, for 0.7A maximum output current, the

maximum inductor ripple current is 300mA. The inductor size is estimated as following equation:

LIDEAL= (V_IN(MAX)-V_OUT)/I_RIPPLE*DMIN*(1/F_OSC

)

Therefore, for V_OUT=5V, the inductor values is calculated to be L=13μH. Chose 10μH or 15Μh

For V_OUT=3.3V, the inductor values is calculated to be L=9.2μH. Chose 10μH

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 8 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

Output Capacitor Selection

For most applications a nominal 22μF or larger capacitor is suitable. The A7407 internal compensation is

designed for a fixed corner frequency that is equal to FC= 8.7KHz

For example, for V_OUT=5V, L=15μH, C_OUT=22μF.

The output capacitor keeps output ripple small and ensures control-loop stability. The output capacitor must

also have low impedance at the switching frequency. Ceramic, polymer, and tantalum capacitors are suitable,

with ceramic exhibiting the lowest ESR and high-frequency impedance. Output ripple with a ceramic output

capacitor is approximately as follows:

_RIPPLE= I_L(PEAK)[1 / (2π x f_OSCx C_OUT)]

If the capacitor has significant ESR, the output ripple component due to capacitor ESR is as follows:

_RIPPLE(ESR) = I_L(PEAK)x ESR

Input Capacitor Selection

The input capacitor in a DC-to-DC converter reduces current peaks drawn from the battery or other input

power source and reduces switching noise in the controller. The impedance of the input capacitor at the

switching frequency should be less than that of the input source so high-frequency switching currents do not

pass through the input source. The output capacitor keeps output ripple small and ensures control-loop

stability.

Components Selection

V_OUT(V)

8.0

_OUT(μF)

L (μH)

15 to 22

10 to 15

6.8 to 10

5.0

3.3

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 9 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

PACKAGE INFORMATION

Dimension in SOT-26 Package (Unit: mm)

SYMBOL

MIN

MAX

1.250

0.100

1.150

0.500

0.200

3.020

1.700

2.950

1.050

0.000

1.050

0.300

0.100

2.820

1.500

2.650

0.950(BSC)

1.800

0.300

0°

2.000

0.600

8°

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 10 -

A7407

DC-DC CONVERTER/ BUCK (STEP-DOWN)

AiT Semiconductor Inc.

www.ait-ic.com

42V INPUT STANDOFF VOLTAGE, 0.7A STEP-DOWN CONVERTER

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.

REV1.1

- MAY 2013 RELEASED, NOV 2014 UPDATED -

- 11 -

A7407E6R [AITSEMI]

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