ITPEC FE Morning April 2018 Question 21
ITPEC FE Morning April 2018 — Question 21 of 80
D/A Converter Resolution — calculate voltage step from DAC specifications.
An 8-bit DAC maps digital input to analog voltage linearly.
Given:
- Input 0 → 0 V
- Input 128 → 2.5 V
Step size (1 LSB change):
- Voltage per unit = 2.5 / 128
- Changing the lowest bit by 1 changes voltage by 2.5/128 V
Why not others:
- (b) 2.5/255 — would apply if max input 255 produced 2.5 V
- (c) 2.5/256 — confuses number of levels (256) with the given mapping
- (d) 2.5/512 — would require 9-bit resolution or different mapping
Key rule: Voltage step = known_voltage / known_input. Use the actual data points given, not assumed max values.
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