DB839 Datasheet, PDF (17/20 Pages) CML Microcircuits – Two Variable Attenuators

Digitally Controlled Analog I/O Processor
17
MX839 PRELIMINARY INFORMATION
Operating Characteristics Notes:
1. Measured over a 0 to 30kHz Band.
2. The extremes of the DAC output range (when resistively loaded) is affected by the output impedance of the DAC
buffer. Under these conditions, the output impedance can approach 200:. However; when the output is operating
well within the supply; the output impedance will be significantly lower, thereby improving the loaded performance.
3. R_LOAD = 5k: AV_DD = 5.0V.
4. Loads less than 1k: will produce output distortion.
5. Small signal impedance, at AV_DD = 5V and T_AMB = 25°C.
6. Differential non-linearity is defined as the difference in width between adjacent code midpoints and the width of an
ideal LSB, divided by the width of an ideal LSB. See Figure 3.
7. Integral non-linearity is defined as the width difference between an actual code midpoint and the line of best fit
through all code midpoints, divided by the width of an ideal LSB. See Figure 4.
8. 6MHz operation at V_DD = 5.0V only. The ‘C-BUS’ clock must be at lest 4 times slower than the XTAL/CLOCK
frequency.
Analog
Output
To
AV_DD
Ideal
Response
Code Width=2LSBs
Differential Non-Linearity=1LSB
0V
000$
Actual Response
To $2FF
Digital
Input
Figure 3: Differential Non-Linearity of a D/A Converter
Analog
Output
768/768
704/768
640/768
576/768
512/768
448/768
384/768
320/768
256/768
192/768
128/768
64/768
0/768
Actual Response
Ideal
Response
5 LSBs
000 040 080 0C0 100 140 180 1C0 200 240 280 2FF
Digital
Input
Figure 4: Integral Non-Linearity of a D/A Converter
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