SMSC DS – USB97CFDC

Page 10

Rev. 12/15/2000

BUFFER TYPE DESCRIPTIONS

Table 1 - USB97CFDC Buffer Type Descriptions

BUFFER

DESCRIPTION

I

Input

IS

Input with Schmitt trigger

O8

Output with 8mA drive

I/O8

Input/output with 8mA drive

OD12

Open drain….12mA sink

O24

Output with 24mA drive

OD24

Open drain….24mA sink

ICLKx

XTAL clock input

OCLKx

XTAL clock output

I/O-U

See Table 6.

BOARD TEST MODE OPERATION

By driving the nTESTEN pin low, the device will be placed into a special test mode to allow verification of attachment

of the device to the circuit board. Every pin except the TSTOUT, XTAL2, and the power and ground pins become an

input to an XNOR chain, as shown below, to allow continuity to be tested on the board. This test should individually

toggle the state of the trace connected to the pin being examined for continuity, and the TSTOUT pin monitored for

toggle of state. If no toggle occurs, either the pin under test is discontinuous, or the TSTOUT pin is not connected on

the board

Pin1

Pin2

Pin3

Pin100

TSTOUT