ADT7470 Analog Devices, Inc., ADT7470 Datasheet - Page 13

• Manufacturer Part Number: ADT7470
• Description: Temperature Sensor Hub And Fan Controller
• Manufacturer: Analog Devices, Inc.

TEMPERATURE READING
The user cannot read the ADT7470’s temperature register values
if the ADT7470 is in the process of a temperature measurement.
The user must wait until the data from all the TMP05s and
TMP06s in the chain are received by the ADT7470 before
reading these values. Otherwise, the temperature registers
may store an incorrect value. It is recommended to wait at
least 200 ms for each TMP05 and TMP06 in the chain. The
recommended procedure is as follows:
TACH3
TACH1
TACH2
PWM2
PWM3
GND
SCL
V
CC
2
3
4
5
6
7
8
1
ADT7470
ADT7470
TMP_START
Figure 13. Interfacing the ADT7470 to Multiple Daisy-Chained TMP05/TMP06 Temperature Sensors
Figure 14. Typical Timing Diagram of ADT7470 with Two TMP05s Connected in Daisy-Chain Mode
TMP_IN
16
15
14
13
12
11
10
9
NOTES:
t
t
t
EACH START/STOP PULSE IS TYPICALLY 25µs.
TMP05s MUST BE IN DAISY-CHAIN MODE.
SEE THE TMP05 DATA SHEET FOR MORE INFORMATION.
SDA
PWM1
SMBALERT
FULL_SPEED/TMP_START
TMP_IN
ADDR
PWM4
TACH4
START
1 STOP
2 STOP
IS GENERATED BY THE ADT7470 AND IS THE START PULSE FOR TMP05 1.
IS GENERATED BY TMP05 2.
IS GENERATED BY TMP05 1 AND IS THE START PULSE FOR TMP05 2.
t
ADT7470
START
t
40ms
1 HIGH
CONV/IN
TMP05/
TMP06
TMP05 1
TEMP = 25°C
NO. 1
Rev. B | Page 13 of 40
t
1
OUT
76ms
t
1 LOW
t
1 STOP
CONV/IN
1.
2.
3.
4.
TMP05/
TMP06
NO. 2
t
Set Register 40<7> = 1. This starts the temperature
measurements.
Wait 200 ms for each TMP05/TMP06 in the loop.
Set Register 40<7> = 0.
Read the temperature registers.
40ms
2 HIGH
OUT
TMP05 2
TEMP = 120°C
t
CONV/IN
2
100ms
TMP05/
t
TMP06
2 LOW
NO. 3
OUT
t
2 STOP
CONV/IN
TMP05/
TMP06
NO. n
OUT
ADT7470