Datasheet

""#
SBAS255C − JUNE 2004 − REVISED APRIL 2009
www.ti.com
24
RETRIEVAL AFTER CONV TOGGLES
(CONTINUOUS MODE)
For shorter integration times, more time is available if data
retrieval begins after CONV toggles and ends before the
new data is ready. Data retrieval must wait t
29
after CONV
toggles before beginning. See Figure 24 for an example of
this. The maximum time available for retrieval is
t
27
−t
29
– t
26
(344.875µs – 10µs – 1.75µs for
CLK = 4MHz), regardless of T
INT
. The maximum number
of DDC114s that can be daisy-chained together (FORMAT
= high) is calculated by Equation 3:
333.125ms
80t
DCLK
NOTE: 64τ
DCLK
is used for FORMAT = low.
For DCLK = 10MHz, the maximum number of DDC114s is
41 (or 52 for FORMAT = low).
SYMBOL
DESCRIPTION
CLK = 4MHz, CLK_4X = 0 CLK = 4.8MHz, CLK_4X = 0
UNITS
SYMBOL
DESCRIPTION
MIN TYP MAX MIN TYP MAX
UNITS
t
26
Hold Time that DOUT is Valid Before Falling Edge of DVALID 1.75 1.458 µs
t
27
Cont Mode Data Ready 345.00 ± 0.125 287.5 ± 0.104 µs
t
29
Data Retrieval Start-Up After Edge of CONV 10 10 µs
Figure 24. Readback After CONV Toggles
(3)
T
INT
t
27
t
29
t
26
T
INT
T
INT
………
………
Side A
Data
Side B
Data
Side A
Data
CONV
DVALID
DCLK
DOUT