Datasheet

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DATA READ OPERATION
CS
t
quiet1
t
su2
t
quiet3
SDO
D17
MSB
1
16 17 18 19
SCLK
D1 D0
LSB
D17 Repeated
BUSY
D15D16
Conversion N
D14 D3 D2
Conversion N+1
t
su5
t
h5
t
cyc
t
d14
t
quiet2
t
w2
t
d13
t
d12
t
h2
No CS
Fall
Zone
CS Fall After This
Point Reads Data
From Conversion
N
CS Fall Before This
Point Reads Data
From Conversion
N−1
CONVST
If There is 19th SCLK
2 3
4
ADS8382
SLAS416B – JUNE 2004 – REVISED NOVEMBER 2004
Data read control is independent of conversion control. Data can be read either during conversion or during
sampling. Data that is read during a conversion involves latency of one sample. The start of a new data frame
around the fall of BUSY is constrained by t
su2
, t
su3
, t
h2
, and t
h8
.
1. SPI interface:
A data read operation in SPI interface mode is shown in Figure 47 . FS must be tied high for operating in this
mode. The MSB of the output data is available at the falling edge of CS. MSB – 1 is shifted out at the first
rising edge after the first falling edge of SCLK after CS falling edge. Subsequent bits are shifted at the
subsequent rising edges of SCLK. If another data frame is attempted (by pulling CS high and subsequently
low) during an active data frame, then the ongoing frame is aborted and a new frame is started.
Figure 47. Read Frame Controlled via CS (FS = 1)
If another data frame is attempted (by pulling CS high and then low) during an active data frame, then the
ongoing frame is aborted and a new frame is started.
2. Serial interface using FS:
A data read operation in this mode is shown in Figure 48 and Figure 49 . The MSB of the output data is
available at the rising edge of FS. MSB – 1 is shifted out at the first rising edge after the first falling edge of
SCLK after the FS falling edge. Subsequent bits are shifted at the subsequent rising edges of SCLK.
19