AMC1210 Datasheet, PDF (23/47 Pages) Burr-Brown (TI) – Quad Digital Filter for 2nd-Order Delta-Sigma Modulator

AMC1210
www.ti.com
SBAS372A – APRIL 2006 – REVISED OCTOBER 2006
Mode 1 (TM = 1)
In Mode 1, the time measure unit updates the Time Register with the elapsed amount of incoming modulator
clock cycles between two rising edges of the selected sample-and-hold signal (selected by the SHS bit of the
Control Parameter Register). This mode can be used to measure the speed of the modulator clock or determine
the number of input bits that have been clocked into the filter module. Each time a positive edge of the selected
sample-and-hold is detected, the Time Register will be updated with the time counter value, and the time
counter will be reset. Figure 18 shows an example of a typical functional timer sequences in Mode 1.
MODE 1 (TM = 1)
SH1
or
SH2
CLKx
TIMER
TIME
REGISTER
123
61 62 63 64 65 66 67
125 126 127 128 1 2 3
61 62 63 64 65 66 67 68 69 70 71
Previous Value
128
Figure 18. Typical Functional Timer Sequence, Mode 1 (TM = 1)
Mode 2 (TM = 0)
In Mode 2, the time measure unit updates the Time Register with the elapsed amount of system clock cycles
from the last available data to the next rising edge of the selected sample-and-hold signal. Each time data is
available, that is, when the sinc filter or the integrator has new data, the timer will reset. The timer continuously
counts when a rising edge of the selected sample-and-hold signal occurs. At this point, the Time Register is
updated with the time counter value, and the time counter will be reset. Figure 19 shows an example of a typical
functional timer sequence in Mode 2.
Since the Time Register is a 16-bit register, the maximum time measured is 65,536 clock cycles. The bit TOx in
the Status Register is set to high when the time counter receives an overflow (that is, when the counter changes
from 0xFFFF to 0x0000). This status bit is reset when the Status Register is read.
MODE 2 (TM = 0)
DATA
REGISTER
SH1
or
SH2
ACK
CLKx
Data Valid
TIMER
TIME
REGISTER
12 3
1 2 3 ^{... ... ... ...}
125 126 127 128 129
12 3
63 64 65 66 67 68 69 70 71
Previous Value
128
67
Figure 19. Typical Functional Timer Sequence, Mode 2 (TM = 0)
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