ADT7475 View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
ADT7475 Datasheet PDF : 68 Pages
| |||
TEMPERATURE MEASUREMENT METHOD
Local Temperature Measurement
The ADT7475 contains an on-chip band gap temperature sensor
whose output is digitized by the on-chip, 10-bit ADC. The 8-bit
MSB temperature data is stored in the temperature registers
(0x25, 0x26, and 0x27). Because both positive and negative
temperatures can be measured, the temperature data is stored in
Offset 64 format or twos complement format, as shown in Table 6
and Table 7.
Theoretically, the temperature sensor and ADC can measure
temperatures from −63°C to +127°C (or −61°C to +191°C in
the extended temperature range) with a resolution of 0.25°C.
However, this exceeds the operating temperature range of
the device, so local temperature measurements outside the
ADT7475 operating temperature range are not possible.
ADT7475
Remote Temperature Measurement
The ADT7475 can measure the temperature of two remote diode
sensors or diode-connected transistors connected to Pin 10 and
Pin 11, or Pin 12 and Pin 13.
The forward voltage of a diode or diode-connected transistor
operated at a constant current exhibits a negative temperature
coefficient of about –2 mV/°C. Unfortunately, the absolute value
of VBE varies from device to device and individual calibration is
required to null this out, so the technique is unsuitable for mass
production.
CPU
VDD
I
N × I IBIAS
REMOTE
SENSING
TRANSISTOR
THERMDA D+
THERMDC D–
BIAS
DIODE
LOW-PASS FILTER
fC = 65kHz
VOUT+
VOUT–
TO ADC
Figure 21. Signal Conditioning for Remote Diode Temperature Sensors
Rev. A | Page 15 of 68
Share Link: 