Telit Wireless Solutions manual UC864-E Hardware User Guide

UC864-E Hardware User Guide

1vv0300766a Rev.1 - 31/01/08

NOTE: The UART input line TXD (rx_uart) of UC864-E is NOT internally pulled up with a resistor, so there may be the need to place an external 47KΩ 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 47KΩ may be required.

A power source of the internal interface voltage corresponding to the 2.6V CMOS high level is available at the PWRMON pin on the connector, whose absolute maximum output current is 1mA.

A maximum of 9 resistors of 47 KΩ pull-up can be connected to the PWRMON pin, provided no other devices are connected to it and the pulled-up lines are UC864-E input lines connected to open collector outputs in order to avoid latch-up problems on UC864-E.

Care must be taken to avoid latch-up on UC864-E 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 UC864-E functionality.

NOTE: The input lines working at 2.6VCMOS can be pulled-up with 47KΩ resistors that can be connected directly to the PWRMON line provided they are connected as in this example.

NO OTHER devices than those suggested should be powered with the PWRMON line; otherwise the module functionality may be compromised.

It is important to consider that the added circuit must have consumption lower than 1mA.

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.

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