EV2108DQ/DK-00A Просмотр технического описания (PDF) - Monolithic Power Systems

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EV2108DQ/DK-00A

2A, 6V, 740KHz Synchronous Buck Converter

Monolithic Power Systems 

MP2108 – 2A, 6V, 740KHz SYNCHRONOUS BUCK CONVERTER

ELECTRICAL CHARACTERISTICS (continued)

VIN = 5.0V, TA = +25°C, unless otherwise noted.

Parameter

Symbol Condition

Oscillator

Switching Frequency

Maximum Duty Cycle

Minimum On Time

Error Amplifier

fSW

DMAX

TON

VFB = 0.7V

Voltage Gain

Transconductance

COMP Maximum Output Current

AVEA

GEA

FB Regulation Voltage

FB Input Bias Current

Soft-Start

VFB

IFB VFB = 0.9V

Soft-Start Current

ISS

Output Switch On-Resistance

Switch On Resistance

Synchronous Rectifier On Resistance

Switch Current Limit (Source)

VIN = 5V

VIN = 3V

VIN = 5V

VIN = 3V

Synchronous Rectifier Current Limit

(Sink)

Thermal Shutdown

Min

Typ

Max Units

620

740

920 KHz

85

%

200

ns

400

V/V

450

µA/V

±40

µA

875

895

915

mV

–100

nA

2

µA

190

mΩ

280

mΩ

160

mΩ

230

mΩ

2.5

3.5

A

350

mA

160

°C

PIN FUNCTIONS

Pin #

1

2

3

4

5

6

7

8

9

10

Name

BST

VIN

LX

PGND

SGND

SS

FB

COMP

VREF

RUN

Description

Power Switch Boost. BST powers the gate of the high-side N-Channel power MOSFET

switch. Connect a 10nF or greater capacitor between BST and LX.

Internal Power Input. VIN supplies the power to the MP2108 through the internal LDO

regulator. Bypass VIN to PGND with a 10µF or greater capacitor. Connect VIN to the input

source voltage.

Output Switching Node. LX is the source of the high-side N-Channel switch and the drain

of the low-side N-Channel switch. Connect the output LC filter between LX and the output.

Power Ground. PGND is the source of the N-Channel MOSFET synchronous rectifier.

Connect PGND to SGND as close to the MP2108 as possible.

Signal Ground.

Soft-Start Input. Place a capacitor from SS to SGND to set the soft-start period. The

MP2108 sources 2µA from SS to the soft-start capacitor at start-up. As the voltage at SS

rises, the feedback threshold voltage increases to limit inrush current at startup.

Feedback Input. FB is the inverting input of the internal error amplifier. Connect a resistive

voltage divider from the output voltage to FB to set the output voltage.

Compensation Node. COMP is the output of the error amplifier. Connect a series RC

network to compensate the regulation control loop.

Internal 2.4V Regulator Bypass. Connect a 10nF capacitor between VREF and SGND to

bypass the internal regulator. Do not apply any load to VREF.

On/Off Control Input. Drive RUN high to turn on the MP2108, drive RUN low to turn the

MP2108 off. For automatic startup, connect RUN to VIN via a 100kΩ pull-up resistor.

MP2108 Rev 1.1

www.MonolithicPower.com

3

10/2/2006

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2006 MPS. All Rights Reserved.

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