LTC1865 LINER [Linear Technology], LTC1865 Datasheet - Page 9

• Manufacturer Part Number: LTC1865
• Description: Ultra-Tiny, Differential, 16-Bit ADC with SPI Interface SPI Interface
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
During the data output operation the CS input pin must
be pulled low (CS = LOW). The data output process starts
with the most significant bit of the result being present
at the SDO output pin (SDO = D15) once CS goes low.
A new data bit appears at the SDO output pin after each
falling edge detected at the SCK input pin. The output
data can be reliably latched by the user using the rising
edge of SCK.
Conversion Status Monitor
For certain applications, the user may wish to monitor
the LTC2452 conversion status. This can be achieved
by holding SCK HIGH during the conversion cycle. In
this condition, whenever the CS input pin is pulled low
(CS = LOW), the SDO output pin will provide an indication
of the conversion status. SDO = HIGH is an indication of
a conversion cycle in progress while SDO = LOW is an
SDO
SCK
CS
SCK = HIGH
t
1
SDO
t
D
MSB
3
CS
15
t
KQ
D
14
D
13
t
1
t
lSCK
CONVERT
D
12
D
Figure 5. Conversion Status Monitoring Mode
11
t
D
hSCK
10
Figure 4. Data Output Timing
t
2
D
9
D
8
D
indication of a completed conversion cycle. An example
of such a sequence is shown in Figure 5.
Conversion status monitoring, while possible, is not re-
quired for LTC2452 as its conversion time is fixed and equal
at approximately 16.6ms (23ms maximum). Therefore,
external timing can be used to determine the completion of a
conversion cycle.
SERIAL INTERFACE
The LTC2452 transmits the conversion result and receives
the start of conversion command through a synchronous
3-wire interface. This interface can be used during the
CONVERT and SLEEP states to assess the conversion
status and during the DATA OUTPUT state to read the
conversion result, and to trigger a new conversion.
7
D
6
D
5
SLEEP
D
4
D
3
D
2
D
1
D
2452 F04
0
LSB
LTC2452
2452 F05
t
2
2452fc
9