User's Manual

Table Of Contents

GC864 Hardware User Guide

1vv0300733 Rev.12 – 2009-06-04

TIP:

This logic IC for the level translator and 2.8V pull-ups (not the 5V one) can be

powered directly from VAUX line of the GC864-QUAD / PY. Note that the TC7SZ07AE

has open drain output; therefore the resistor R2 is mandatory.

NOTE:

The UART input line TXD (rx_uart) of the GC864-QUAD / PY is NOT internally pulled

up with a resistor, so there may be the need to place an external 47K pull-up

resistor, either the DTR (dtr_uart) and RTS (rts_uart) input lines are not pulled up

internally, so an external pull-up resistor of 47K may be required.

A power source of the internal interface voltage corresponding to the 2.8VCMOS high

level is available at the VAUX pin on the connector,

A maximum of 9 resistors of 47 K pull-up can be connected to the VAUX pin,

provided no other devices are connected to it and the pulled-up lines are GC864-

QUAD / PY input lines connected to open collector outputs in order to avoid latch-up

problems on the GC864-QUAD / PY.

Care must be taken to avoid latch-up on the GC864-QUAD / PY and the use of this

output line to power electronic devices shall be avoided, especially for devices that

generate spikes and noise such as switching level translators, micro controllers,

failure in any of these condition can severely compromise the GC864-QUAD / PY

functionality.

NOTE:

The input lines working at 2.8VCMOS can be pulled-up with 47K resistors that can

be connected directly to the VAUX line provided they are connected as in this

example.

In case of reprogramming of the module has to be considered the use of the RESET

line to start correctly the activity.

The preferable configuration is having an external supply for the buffer.