Can I omit the input resistor for the LM3875?

sardonx

Member
2003-06-22 11:34 pm
Canada
Is it safe to not use a resistor at pin7 (1K) for the LM3875?

The LM datasheet show it there but even just looking at the resistor on the schematic is making me wish it wasn't there. I'm using an OTL pre-amp right before the amp.. so it would be nice to be able to go straight into the chip with no dirty resistors in between. Should I build the amp with or without the input resistor?
 
the reason for the resitor is in the datasheet and is related to reliability. apparently there is a potential condition where high current would be allowed (if possible) to flow into the inputs and destroy parts of the amplifier during turn on or turn off.

in memory no one on these forums has ever had this issue with the IC.

the resistor also appears in the DC offset due to input bias current mismatch equation.