User's Manual

HC864-AUTO Hardware User Guide
1vv0300946 Rev.4 – 2012-12-27
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Reserved. Page 48 of 77
TIP:
This logic IC for the level translator and 2.6V pull-ups (not the 5V one) can be powered
directly from VAUX1 line of HC864-AUTO. Note that the TC7SZ07AE has open drain
output; therefore the resistor R2 is mandatory.
A power source of the internal interface voltage corresponding to the 2.6V CMOS high level
is available at the VAUX1 pin on the connector.
A maximum of 9 resistors of 47 K pull-up can be connected to the VAUX1 pin, provided no
other devices are connected to it and the pulled-up lines are HC864-AUTO input lines
connected to open collector outputs in order to avoid latch-up problems on HC864-AUTO.
Careful approach is needed to avoid latch-up on HC864-AUTO and the use of this output line
to power electronic devices must 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 HC864-AUTO functionality.
TIP:
The input lines working at 2.6VCMOS can be pulled-up with 47K resistors that can be
connected directly to the VAUX1 line. It is a must that they are connected as in this example.
The preferable configuration is having external supply for the buffer.