# the common mode limit of VCOp, VCOn in HMC984 datasheet

The HMC984 VCOp/n inputs have a common mode limit of VCCPD-1.4.

[1] does this limit specifies that no more than 1.4Volt can be applied across the internal 50 Ohm pull-up resistors ? otherwise the internal 50ohm could be burn out due to a constant dc power 1.4V^2/50ohm=40mW power through such resistor ?

or

[2] does the limit specifies that no more than 3.6V (=5V-1.4V) common mode should be applied for such resistors ?

in the case where 2.5V (which is smaller than 3.6V) common mode is applied for such 50 ohm, there would be a constant DC power 2.5V^2/50ohm=0.125Watt=50mA^2*50ohm through such 50 ohm pull-up resistor; a signal current 15mApp or 750mVpp (=15mApp*50Ohm) single ended should be typically applied on such common mode.

Which definition is specified in the absolute maximum table of HMC984 ?

tag
[edited by: lallison at 5:08 PM (GMT 0) on 16 Jul 2019]