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dac8800FPZ glitch


I am using the old DAC8800 8 Channel DAC on a project, its pretty basic where I pass an 8 bit value to channel 1 of the DAC8800

The problem I have discovered is the ladder inside the chip appears to be incorrectly built.


V1RH, V2RH, VDD set to 12v

V1RL, V2RL,/CLK, VSS set to 0V

/CLR set to +5v

SDI Data in

Clk Data In

Load on completion

Address 000 = Channel 1

Data 255     =     10.86v

Data 254     =     10.67v

Data 253     =     10.73v     - Voltage goes up
Data 252     =     10.46v

Data 251     =     10.61v     - Voltage goes up

Data 250     =     9.90v

Data 249     =     10.14v    - Voltage goes up

This appears to continue until we are less than decimal 64

To verify that my software is correct, I setup a breadboard with switches to manually verify this and the results were the same.

Any ideas??


The chips is labelled