NET2272 datasheet(52/102 Pages) ETC2

52 / 102 page

Specification

NET2272 USB Peripheral Controller

______________________________________________________________________________

 NetChip Technology, Inc., 2003

Patent Pending

335 Pioneer Way, Mountain View, California 94041

TEL (650) 526-1490

FAX (650) 526-1494

http://www.netchip.com

Rev 1.2, October 15, 2003

In power-sensitive applications, the local CPU can force the NET2272 to enter low-power suspend mode when

disconnected from the USB by writing a 1 to the Suspend Request Interrupt bit. The NET2272 will automatically

wake-up when the peripheral is re-connected (cable plugged in and USB Detect Enable bit set) to the USB. Do not

force suspend mode unless the peripheral is disconnected from the USB. When the NET2272 is connected to the

USB, it is a violation of the USB specification to enter the suspend state unless the upstream port has been idle for

at least 3 milliseconds.

This is the preferred method of suspending the NET2272, since a USB re-connection will automatically cause the

NET2272 to wake-up and set the Resume Interrupt bit.

7.2.2.2 Power-On Standby

The local CPU can prevent the NET2272 from starting its oscillator on power-up by driving a LOW into the CS#

pin while RESET# is asserted (LOW). In this state the NET2272 requires only a small quiescent standby current.

When the peripheral wishes to start the oscillator, it releases the CS# pin and continues to assert RESET# for a

minimum of 2 milliseconds. Note that while the oscillator is stopped, the NET2272 cannot respond to USB

requests, so the oscillator must be allowed to start when the peripheral detects a USB connection event. The local

CPU is responsible for detecting the connection, and ending the standby condition.

This standby technique is appropriate when the device’s power budget does not allow the NET2272 to be active

long enough to shut it down by setting the Suspend Request Interrupt bit.

NET2272 数据表(PDF) 52 Page - List of Unclassifed Manufacturers