AD7417 AD [Analog Devices], AD7417 Datasheet - Page 16

• Manufacturer Part Number: AD7417
• Description: 10-Bit Digital Temperature Sensor (AD7416) and Single/Four-Channel ADC (AD7417/AD7418)
• Manufacturer: AD [Analog Devices]

AD7416/AD7417/AD7418
FAN CONTROLLER
Figure 14 shows a simple fan controller that will switch ON a
cooling fan when the temperature exceeds 80°C and switch it
OFF again when the temperature falls below 75°C. The AD7416
can be used standalone in this application or with a serial bus
interface if different trip temperatures are required. If the AD7416
is used with a bus interface, the sense of OTI can be set to active
high, Q1 and R1 can be omitted, and OTI can be connected
directly to the gate of Q2 with R2 as the pull-up resistor.
3V TO 5.5V
Figure 17. CONVST When Temperature Channel Selected
V
DD
Figure 14. AD7416 Used as a Fan Controller
3V TO 5.5V
CONVST
AD7416
V
DD
R1
10k
100ns
R1
10k
40 s
R2
10k
Q1
2N3904
OR SIMILAR
Figure 16. Multiple Connection of AD7416s to a Single Serial Bus
12V
Q2
LOGIC LEVEL
MOSFET RATED
TO SUIT FAN
CURRENT
–16–
THERMOSTAT
Figure 15 shows the AD7416 used as a thermostat. The heater
will be switched ON when the temperature falls below T
and switched OFF again when the temperature rises above
T
output should be programmed active low.
SYSTEM WITH MULTIPLE AD7416S
The three LSBs of the AD7416’s serial address can be set by the
user, allowing eight different addresses from 1001000 to 1001111.
Figure 16 shows a system in which eight AD7416s are connected
to a single serial bus, with their OTI outputs wire-ANDed
together to form a common interrupt line. This arrangement
does mean that each device must be read to determine which
one has generated the interrupt, and if a unique interrupt is
required for each device, the OTI outputs can be connected
separately to the I/O chip.
OTI
. For this application and for comparator mode, the OTI
Figure 18. CONVST When V
AD7416
Figure 15. AD7416 Used as a Thermostat
3V TO
CONVST
5.5V
V
DD
100ns
R1
10k
RELAY
15 s
Q1
2N3904
OR SIMILAR
IN
Channel(s) Selected
D1
1N4001
HEATER
RLA1
HEATER
SUPPLY
REV. G
HYST