DDC112_15 Datasheet, PDF (19/34 Pages) Texas Instruments – 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 integration 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.
DDC112
19
SBAS085B
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