Datasheet > USB2227_0503

USB2227_0503

更新时间： 2024-09-26 03:56:43

品牌	Logo	应用领域
SMSC		闪存
页数	文件大小	规格书
5页	166K
描述
Flash Card Reader Media Power Considerations

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USB2227_0503 数据手册

WP 1.5

USB2227 and USB2228 USB2.0 Flash Card

Reader Media Power Considerations

Introduction

Bus-powered USB2.0 Flash Media Card Readers are enjoying an explosive growth due to the

increasing popularity of digital photography and portable music players. The basic card formats now

stand at four types, but all of these require the careful implementation of their power control. Historically,

this is provided via discrete power FETs which are external to the card reader controller (e.g. SMSC’s

USB2223 and USB2224 devices), and requires careful design and component selection to avoid

several possible system issues. This paper addresses some of those issues.

In addition, fourth generation controllers, such as SMSC’s USB2227 and USB2228 devices, integrate

some of the power FETs internally to the controller itself, to further save system cost. The design of

these integrated FETs must account for these issues also in order to obtain successful operation.

Design Considerations

Figure 1 illustrates a typical card reader implementation and the card power supply circuit.

I_m1

3.3V

Regulator

Cin

Cout

V_m1

VDD

Ccard

Card

VBUS

USB2.0

Power

Control

Flash Card

Reader

USB

Card Detect

Figure 1 Card Reader Implementation/Card Power Supply Circuit

In operation, when the user inserts the card into its socket, the card insertion is signaled to the Reader

Controller which then applies power, by driving the power FET, M1, on. In many cases, the turn on time

of the FET is managed via Rg/Cg.

SMSC WP 1.5

WHITE PAPER

Revision 1.1 (03-31-05)

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与USB2227_0503相关器件

型号	品牌	获取价格	描述	数据表
USB2227_06	SMSC	获取价格	4th Generation USB2.0 Flash Media Controller with Integrated Card Power FETs
USB2227-AHZS-XX	SMSC	获取价格	4th Generation USB2.0 Flash Media Controller with Integrated Card Power FETs
USB2227-NE-04	SMSC	获取价格	Bus Controller, PQFP128
USB2227-NE-XX	SMSC	获取价格	4TH GENERATION USB2.0 FLASH MEDIA CONTROLLER WITH INTEGRATED CARD POWER FETS
USB2227-NU-03	SMSC	获取价格	Bus Controller, PQFP128
USB2227-NU-05	SMSC	获取价格	4th Generation USB2.0 Flash Media Controller with Integrated Card Power FETs
USB2227-NU-11	MICROCHIP	获取价格	IDE COMPATIBLE, FLASH MEMORY DRIVE CONTROLLER, PQFP128, 14 X 14 MM, 1 MM HEIGHT, ROHS COMP
USB2227-NU-11	SMSC	获取价格	Flash Memory Drive, IDE Compatible, CMOS, PQFP128, 14 X 14 MM, 1 MM HEIGHT, ROHS COMPLIANT
USB2227-NU-XX	SMSC	获取价格	4TH GENERATION USB2.0 FLASH MEDIA CONTROLLER WITH INTEGRATED CARD POWER FETS
USB2228	SMSC	获取价格	4TH GENERATION USB2.0 FLASH MEDIA CONTROLLER WITH INTEGRATED CARD POWER FETS