PC87591E Datasheet, PDF (191/437 Pages) National Semiconductor (TI) – LPC Mobile Embedded Controllers

Embedded Controller Modules (Continued)
Voltage Ratio to AV_CC
1
255/256
254/256
3/256
2/256
1/256
0
Level Data
01 23
....
254 255 (256) [LSBits]
Figure 66. Channel Data to Output Voltage Ratio Conversion
When the value of DACDATA7-0 is 00₁₆, the respective output has an output signal of 0V (AGND). When the value of
DACDATn register is FF₁₆, the respective output has an output signal of (255/256) _* AV_CC. For other values, as shown in
Figure 66:
V_OUT = (DACDATAn) _* (AV_CC / 256)
Reference Voltage
The analog output voltages are converted relative to a reference voltage. The reference voltage of the converters is the an-
alog power supply. To assure good signal quality at the output, a low-noise analog power supply should be used.
Conversion Time
When a DAC channel is enabled, the conversion is started by writing to DACDATn registers. The output settling time is de-
fined as the time the DAC requires to get to within 1/2 LSB of the final value; see “Output Settling Time” on page 195.
Revision 1.07
191
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