Book Analog Interfacing to Embedded Microprocessors
another 4-bit flash to produce the LS 4 bits of the result.
Figure 2.7
Half-flash converter.
Digital-to-Analog Converters 25
If the converter shown in Figure 2.7 were a 0–5v converter, converting a
3.1v input, then the conversion would look like this:
Upper flash converter output = 9
DAC output = 2.8125 v (9 ¥ 16 ¥ 19.53 mv )
Subtracter output = 3.1v - 2.8125v = .2875v
Lower flash converter output = E(hex)
Final result = 9E (hex), 158 (decimal)
Half-flash converters can also use three stages instead of two; a 12-bit
converter might have three stages of 4 bits each. The result of the MS 4 bits
would be subtracted from the input voltage and applied to the middle 4-bit
state. The result of the middle stage would be subtracted from its input and
applied to the least significant 4-bit stage
annaabi.ee 
