DDC232 Datasheet, PDF (19/28 Pages) Burr-Brown (TI) – 32-Channel, Current-Input Analog-to-Digital Converter

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Changing Between Modes
Changing from cont to ncont mode occurs whenever
t_INT < t_MRAZ. Figure 15 shows an example of this
transition. In this figure, cont mode is entered when
the integration on side A is completed before the
m/r/az cycle on side B is complete. The DDC232
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 ncont to cont mode occurs when t_INT
DDC232
SBAS331C – AUGUST 2004 – REVISED SEPTEMBER 2006
is increased so that t_INT is always ≥ t_MRAZ as shown
in Figure 16 (see Figure 13 and Table 7, page 18).
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 < t_MRAZ. This
is allowed because there is no simultaneous m/r/az
cycle on the side B during state 3—therefore, 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
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
mbsy
Figure 15. Changing from Continuous Mode to Non-Continuous Mode
CONV
State
Integration
Status
m/r/az
Status
3
4
Int A Int B
1
2
Non−Continuous
m/r/az A
m/r/az B
3
Continuous
Integrate A
4
Integrate B
m/r/az A
mbsy
Figure 16. Changing from Non-Continuous Mode to Continuous Mode
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