ADT7470ARQZ Analog Devices Inc, ADT7470ARQZ Datasheet - Page 13

• Manufacturer Part Number: ADT7470ARQZ
• Description: IC SENSOR TEMP FAN CTRLR 16QSOP
• Manufacturer: Analog Devices Inc

Specifications of ADT7470ARQZ

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Control, Register Bank
• Sensor Type: External
• Sensing Temperature: External Sensor
• Output Type: I²C™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Ic Output Type: Digital
• Sensing Accuracy Range: ± 12%
• Supply Current: 500µA
• Supply Voltage Range: 3V To 5.5V
• Sensor Case Style: QSOP
• No. Of Pins: 16
• Msl: MSL 3 - 168 Hours
• Termination Type: SMD
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Accuracy %: 12%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADT7470EBZ - BOARD EVALUATION FOR ADT7470
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

TEMPERATURE MEASUREMENT USING TMP05/TMP06
MEASURING TEMPERATURE
The ADT7470 can be connected with up to 10 daisy-chained
TMP05/TMP06 devices for temperature measurement. Each
TMP05/TMP06 performs an ambient temperature measure-
ment, and outputs a PWM signal. The ADT7470 decodes the
PWM into a temperature measurement, and stores the result
in the temperature reading registers, listed in Table 7.The
maximum temperature read back from all TMP05 temperature
readings is stored in register 0x78.
To use the ADT7470 with TMP05/TMP06, the parts should be
connected as shown in Figure 13. Pin 13 on the ADT7470
should be configured as TMP_START, by setting Configuration
Register 1 Bit 7 to Bit 1. (Register address 0x40 Bit[7] =1). The
start pulse required by the TMP05/06 will be output on the
TMP_START pin. The OUT pin on the last TMP05/06 in the
daisy-chain should be connected to Pin 12 on the ADT7470,
TMP_IN. For more information on the TMP05/06, refer to the
TMP05/TMP06 data sheet.
Reporting of 8-bit temperature values occurs only if the
TMP_IN function is used and if TMP05/TMP06s are daisy-
chained according to their data sheet and connected as shown.
The ADT7470 does not have any temperature measurement
capability when used as a standalone device without TMP05s
and TMP06s connected.
TACH3
TACH1
TACH2
PWM2
PWM3
GND
SCL
V
CC
2
3
4
5
6
7
8
1
ADT7470
Figure 13. Interfacing the ADT7470 to Multiple Daisy-Chained TMP05/TMP06 Temperature Sensors
16
15
14
13
12
11
10
9
SDA
PWM1
SMBALERT
FULL_SPEED/TMP_START
TMP_IN
ADDR
PWM4
TACH4
CONV/IN
TMP05/
TMP06
NO. 1
Rev. C | Page 13 of 40
OUT
CONV/IN
Table 7. Temperature Reading Registers
Register
0x20
0x21
0x22
0x23
0x24
0x25
0x26
0x27
0x28
0x29
0x78
TMP05/TMP06 Decoder
The ADT7470 includes a PWM processing engine to decode the
daisy-chained PWM output from multiple TMP05s and TMP06s.
It then passes each decoded temperature value to the temper-
ature value registers. This allows the ADT7470 to do high/
low limit comparisons of temperature and to automatically
control fan speed based on measured temperature. The PWM
processing engine contains all necessary logic to initiate start
conversions on the first daisy-chained TMP05/TMP06 and
to synchronize with each temperature value as it is fed back to
the device through the daisy chain. The start function is multi-
plexed onto the same pin that can be used to blast the fans
to full speed. The start conversion for TMP05/TMP06 temp-
erature measurement is fully transparent to the user and does
not require any software intervention to function.
TMP05/
TMP06
NO. 2
OUT
Reading
Temperature 1 reading
Temperature 2 reading
Temperature 3 reading
Temperature 4 reading
Temperature 5 reading
Temperature 6 reading
Temperature 7 reading
Temperature 8 reading
Temperature 9 reading
Temperature 10 reading
Max TMP05 temperature
CONV/IN
TMP05/
TMP06
NO. 3
OUT
CONV/IN
TMP05/
TMP06
NO. n
OUT
Default
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
ADT7470