CS5510/11/12/13
16 DS337F4
2.5.1 Reading Conversions -
CS5510/12
After power-up, the CS5510/12 will begin convert-
ing once a clock source is applied to the SCLK pin.
When a conversion has completed, and there is
new data in the output register, the SDO line will
fall to a logic-low level if CS
is also at a logic-low
state (SDO will always be high-impedance when
CS
is high). If CS is low at the end of the conver-
sion cycle, SDO will fall on the rising edge of an
SCLK. After SCLK falls, the next SCLK cycle (high,
then low) will begin clocking out the data. The first
data bit therefore, is 1-
½ SCLK cycles wide. Twen-
ty-four SCLK cycles (after the initial high-low tran-
sition) are needed to retrieve the conversion word
from the device (see Figures 16 and 17). The data
bits can be read on the rising edge of SCLK, and
the next data bit is output to SDO on the falling
edge of SCLK. Once the entire data word has been
read, SDO will return to a logic-high state until
there is a new conversion word available. If CS
is
at a logic-high at the end of the conversion cycle,
the data will not be shifted out of the part until CS
is brought to a logic-low state during the next con-
version cycle. If a new conversion becomes avail-
able while the current data is being read, the data
register will not be updated, and the new conver-
sion word will be lost. The user need not read every
conversion. If the user chooses not to read a con-
version, CS
should remain at a logic-high state for
the duration of the conversion cycle. Note that if
CS
goes to a logic-high state during a read, the
current conversion data will be lost and replaced
by a new conversion word when the new conver-
sion data is available.
2.5.2 Reading Conversions -
CS5511/13
After power-up, the CS5511/13 begins converting
and updating the output register. When there is
new data in the output register (at the end of a con-
version cycle) the SDO line will fall to a logic-low
level if CS
is also at a logic-low state (SDO will al-
ways be high-impedance when CS
is high). Twen-
ty-four SCLK cycles are needed to retrieve the
conversion word from the device (see Figures 18
and 19). The data bits can be read on the rising
edge of SCLK, and the next data bit is output to
SDO on the falling edge of SCLK. Once the entire
data word has been read, SDO will return to a log-
ic-high state until there is a new conversion word
available. If new conversions become available
while the current data is being read, the data regis-
ter will not be updated, and the new conversions
will be lost. The user need not read every conver-
sion. If the user chooses not to read a conversion
after SDO falls, SDO will rise seventeen oscillator
clock cycles (of the internal oscillator) before the
next conversion word is available and then fall
again to signal that the conversion is complete.
Note that if a conversion word is not read before
the next conversion word is ready, or if CS
goes to
a logic-high state during a read, the current conver-
sion data will be lost and replaced by a new con-
version word when the new conversion data is
available.
SDO
SCLK
Data Time
24 SCLKs
MSB
LSB
CS
0OF OD 000 0 0
0
0
Figure 16. Data Word Timing for the CS5510.
