AD7817 AD [Analog Devices], AD7817 Datasheet - Page 14

• Manufacturer Part Number: AD7817
• Description: Single- and 4-Channel, 9 us, 10-Bit ADCs with On-Chip Temperature Sensor
• Manufacturer: AD [Analog Devices]

AD7816/AD7817/AD7818
Figure 14. Self-Heating Effect in Air, Fluid, and in Thermal
Contact with a Heat Sink
Figure 15. Self-Heating Effect in Air, Fluid, and in Thermal
Contact with a Heat Sink
–0.05
–0.01
0.25
0.20
0.15
0.10
0.05
0.00
0.8
0.7
0.6
0.5
0.4
0.2
0.0
0.3
0.1
0.0
0
2
CONVST
RD/ WR
BUSY
SCLK
D
0.5
OTI
OUT
4
D
CS
IN
6
AIR
TIME – secs
FLUID
AIR
TIME – secs
1.0
8
HEAT SINK
10
DB7 – DB0
1.5
12
FLUID
HEATSINK
14
Figure 16. Mode 1 Operation
t
17
t
2.0
3
16
t
2
t
–14–
1
OPERATING MODES
The AD7816, AD7817, and AD7818 have two possible modes
of operation depending on the state of the CONVST pulse at
the end of a conversion.
Mode 1
In this mode of operation the CONVST pulse is brought high
before the end of a conversion, i.e., before the BUSY goes low
(see Figure 16). When operating in this mode a new conversion
should not be initiated until 100 ns after the end of a serial read
operation. This quiet time is to allow the track/hold to accu-
rately acquire the input signal after a serial read.
Mode 2
When the AD7816, AD7817, and AD7818 are operated in Mode
2 (see Figure 17), they automatically power down at the end of
a conversion. The CONVST is brought low to initiate a conver-
sion and is left logic low until after the end of the conversion. At
this point, i.e., when BUSY goes low, the devices will power-
down. The devices are powered up again on the rising edge of
the CONVST signal. Superior power performance can be
achieved in this mode of operation by powering up the AD7816,
AD7817, and AD7818 only to carry out a conversion (see Power
vs. Throughput section). In Figure 17 the CS line is applicable
to the AD7817 only.
t
15
t
16
DB7(DB9) – DB0
REV. C