Datasheet

LTC2433-1
14
24331fa
The serial data output pin (SDO) is Hi-Z as long as CS is
HIGH. At any time during the conversion cycle, CS may be
pulled LOW in order to monitor the state of the converter.
While CS is pulled LOW, EOC is output to the SDO pin.
EOC␣ =␣ 1 while a conversion is in progress and EOC = 0 if
the device is in the sleep state. With CS high, the device
automatically enters the low power sleep state once the
conversion is complete.
When the device is in the sleep state (EOC = 0), its
conversion result is held in an internal static shift regis-
ter. Data is shifted out the SDO pin on each falling edge of
SCK. This enables external circuitry to latch the output on
the rising edge of SCK. EOC can be latched on the first
rising edge of SCK and the last bit of the conversion result
can be latched on the 19th rising edge of SCK. On the 19th
falling edge of SCK, the device begins a new conversion.
SDO goes HIGH (EOC = 1) indicating a conversion is in
progress.
At the conclusion of the data cycle, CS may remain LOW
and EOC monitored as an end-of-conversion interrupt.
Alternatively, CS may be driven HIGH setting SDO to Hi-Z.
As described above, CS may be pulled LOW at any time in
order to monitor the conversion status.
Typically, CS remains LOW during the data output state.
However, the data output state may be aborted by pulling
CS HIGH anytime between the first rising edge and the
19th falling edge of SCK, see Figure 7. On the rising edge
of CS, the device aborts the data output state and imme-
diately initiates a new conversion. This is useful for abort-
ing an invalid conversion cycle or synchronizing the start
of a conversion.
Figure 7. External Serial Clock, Reduced Data Output Length
SDO
SCK
(EXTERNAL)
CS
DATA
OUTPUT
CONVERSION
SLEEP
SLEEP
TEST EOC (OPTIONAL)
TEST EOC
DATA OUTPUT
Hi-Z Hi-ZHi-Z
CONVERSION
24331 F07
MSBSIG“O”
BIT 4BIT 14 BIT 5BIT 15BIT 16BIT 17
EOC
BIT 18BIT 0
EOC
Hi-Z
TEST EOC
SLEEP
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/SIMULTANEOUS
50Hz/60Hz REJECTION
V
CC
F
O
REF
+
REF
–
SCK
IN
+
IN
–
SDO
GND
CS
110
2
3
9
4
5
8
6
7
REFERENCE
VOLTAGE
0.1V TO V
CC
ANALOG INPUT RANGE
–0.5V
REF
TO 0.5V
REF
1µF
2.7V TO 5.5V
LTC2433-1
3-WIRE
SPI INTERFACE
APPLICATIO S I FOR ATIO
WUUU