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  • TI Thinks Resolved

ONET4291PA: Issues with Programming and Allowable Max Signal Input

Part Number: ONET4291PA

I am using a TI EvalPCBA supplied by our TI rep.

1) I am unable to program the device.  

I have read the datasheet thoroughly and it seems simple enough (e.g. pg5). I suspect the datasheet is incorrectly written...

-By default SDA/SCK are HI
-START initiated by going LO while SCK remains HI, followed by SCK going low
-Data is clocked in when SCK is clocked.
-Clock in 11 bits (MSB First): First 3 are address for register 4 or 5, next 8 are data bits.
-END initiated by SCK going HI, followed by SDA going HI.

I am trying to increase the output swing from 400mVpp (Default 00 in registers A1 A0) to 1Vpp (11 in A1 A0). The bitcommand for this is 10111000000. (RegAddress5 = 101, A1A0 = 11, rest 0's since I'm using external pot for threshold).

See waveform below and please explain why my bitstream instruction is not working... I am pretty confident I am following the protocal and I suspect the datasheet is incorrectly written...

2) Page 9 lists the "Vdin_diff_Max as +/-1.25V", and Page10 lists the "VIN_max_Overload = 2Vpp". Are we sure this isn't off by a factor of 2x?
I am driving this part differentially (50-ohm source) and have seen proper operation with ~4Vpp (note this is double what the spec is written as) with no increase in power supply current draw nor issues in signal fidelity (common signs of proper overload). I'm suspecting an error of 2x in the datasheet due to differential drive? Or perhaps this swing is rated for ~1GHz? My application is only 13MHz and I see no issues with larger signal... Would like to confirm that's okay based on chip internal design.

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