On 27 abr, 00:53, Rich Webb wrote:
Yes, slowly rising supplies can be a killer.

Holding /OE of the LCX244 might do the trick. The old standby RC setup
would probably work, although one of the many supervisory chips would be
more robust.

--
Rich Webb * * Norfolk, VA

After trying many solutions this is the simplest working one:

VCC
+
|
.-.
| |
100K| |
'-'
|
+-- /OE
|
___ |/
/RST --|___|-+----| BC548
560K | |
|+ |
4.7uF === |
/-\ |
|______|
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

The 100K pull-up resistor keeps all outputs in tri-state during power
up ramp as per LCX244 datasheet and it actually works. When /RST goes
high it will start to charge the capacitor slowly and some hundred
milliseconds later will polarize the transistor that will ground /OE
and enable communication with a perfect transition. I have tested this
in a proto board with wires soldered to the unit and works great, have
been turning on and off the unit repeatedly now and then and no more
reboots!

Initially I targeted to remove the slow ramp only and it did not fix
the issue. Apparently the ramp does not cause the reboots or is not
the only reason for them. So I increased the delay to also remove two
or three bursts received from the main unit that look like ACK of some
sort as they are all very short and appear to carry no useful
information at all (I can't say they cause the reboots because they
are present and are identical when it starts fine). I adjusted the
delay so that communication will be enabled around 100ms before the
first useful burst and that appears to do the trick.

Thank you so much for all your help!

By the way this is a Kaon KVR-1000TS+