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When transmitter is disabled, on LT1785, there is current source pulling the -DATA pin to VCC through a 100Ω resistor to ground. I replaced the 1785 with a ST4E1240DT and the 100Ω pulled the -DATA pin to ~300mV. Changing back to the 1785 my problem ret

Category: Hardware
Product Number: LT1785

When transmitter is disabled, on LT1785, there is current source pulling the -DATA pin to VCC through a 100Ω resistor to ground. I replaced the 1785 with a ST4E1240DT and the 100Ω pulled the     -DATA pin to ~300mV. Changing back to the 1785 my problem returned.  What should I expect the leakage current to be? Cause right now it appears to be around 50mA.

Here is the transmission of 0x03. 1st 3 bits shown,

Bottom trace is Tx enable, top is -D.

In my application I have 100Ω pull up on +D and on -D.

I invert TX data from UART as the enable.

The 100Ω resistor was suppose to keep -D low until enable occurs.

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