DDC112 Datasheet, PDF (17/24 Pages) Burr-Brown (TI) – Dual Current Input 20-Bit ANALOG-TO-DIGITAL CONVERTER

Changing Between Modes
Changing from the cont to ncont mode occurs whenever
T_INT < t₆. Figure 18 shows an example of this transition.
In this figure, the cont mode is entered when the integration
on side A is completed before the m/r/az cycle on side B is
complete. The DDC112 completes the measurement on sides
B and A during states 8 and 7 with the input signal shorted
to ground. Ncont integration begins with state 6.
Changing from the ncont to cont mode occurs when T_INT is
increased so that T_INT is always ≥ t₆ (see Figure 14). With a
longer T_INT, the m/r/az cycle has enough time to finish
before the next integration begins and continuous integra-
tion of the input signal is possible. For the special case of the
very first integration when changing to the cont mode, T_INT
can be < t₆. This is allowed because there is no simultaneous
m/r/az cycle on the side B during state 3—there is no need
to wait for it to finish before ending the integration on side A.
CONV
State
5
Integration
Status
Integrate A
m/r/az
Status
m/r/az B
mbsy
4
5
Continuous
Integrate B
Int A
8
Non-Continuous
76
5
Int B Int A
m/r/az A
m/r/az B
m/r/az A
m/r/az B
FIGURE 18. Changing from Continuous Mode to Non-Continuous Mode.
CONV
State
3
4
Integration
Status
Int A Int B
1
2
Non-Continuous
m/r/az
Status
m/r/az A
m/r/az B
3
Continuous
Integrate A
mbsy
4
Integrate B
m/r/az A
FIGURE 19. Changing from Non-Continuous Mode to Continuous Mode.
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DDC112