ADT7517ARQ Analog Devices Inc, ADT7517ARQ Datasheet - Page 19

• Manufacturer Part Number: ADT7517ARQ
• Description: IC TEMP SNSR QUAD DAC 16-QSOP
• Manufacturer: Analog Devices Inc

Specifications of ADT7517ARQ

• Rohs Status: RoHS non-compliant
• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 120°C, External Sensor
• Output Type: I²C™, MICROWIRE™, QSPI™, SPI™
• Output Alarm: No
• Output Fan: No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 120°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP

THEORY OF OPERATION
Directly after the power-up calibration routine, the ADT7516/
ADT7517/ADT7519 go into idle mode. In this mode, the
devices are not performing any measurements and are fully
powered up. All four DAC outputs are at 0 V.
To begin monitoring, write to the Control Configuration 1
register (Address 0x18) and set Bit C0 = 1. The ADT7516/
ADT7517/ADT7519 go into the power-up default measurement
mode (round robin). The devices proceed to take measurements
on the V
external temperature sensor channel (AIN1 and AIN2), AIN3,
and finally AIN4. After they finish taking measurements on the
AIN4 channel, the devices immediately loop back to start
taking measurements on the V
cycle as before. This loop continues until the monitoring is
stopped by resetting Bit C0 of the Control Configuration 1
register to 0.
It is also possible to continue monitoring as well as switching to
single-channel mode by writing to the Control Configuration 2
register (Address 0x19) and setting Bit C4 = 1. Further explana-
tion of the single-channel and round robin measurement modes
is given in later sections. All measurement channels have
averaging enabled on them at power-up. Averaging forces the
devices to take an average of 16 readings before giving a final
measured result. To disable averaging and consequently
decrease the conversion time by a factor of 16, set Bit C5 = 1 in
the Control Configuration 2 register.
There are four single-ended analog input channels on the
ADT7516/ADT7517/ADT7519, AIN1 to AIN4. AIN1 and
AIN2 are multiplexed with the external temperature sensor
terminals (D+ and D−). Bit C1 and Bit C2 of the Control
Configuration 1 register (Address 0x18) are used to select
between AIN1/AIN2 and the external temperature sensor.
The input range on the analog input channels is dependent on
whether the ADC reference used is the internal V
meet linearity specifications, it is recommended that the maximum
V
be used to select between the internal reference and V
ADC reference of the analog inputs.
Controlling the DAC outputs can be done by writing to the MSB
and LSB registers of the DAC (Address 0x10 to Address 0x17).
The power-up default setting is to have a low going pulse on the
LDAC pin (Pin 9) controlling the updating of the DAC outputs
from the DAC registers. Alternatively, one can configure the
updating of the DAC outputs to be controlled by means other
than the LDAC pin by setting Bit C3 = 1 of the Control
Configuration 3 register (Address 0x1A). The DAC configura-
tion register (Address 0x1B) and the LDAC configuration
register (Address 0x1C) can now be used to control the DAC
updating. These two registers also control the output range of
the DACs and select between the internal or external reference.
DD
value is 5 V. Bit C4 of the Control Configuration 3 register
DD
channel, internal temperature sensor channel,
DD
channel and repeat the same
REF
or V
DD
as the
DD
. To
Rev. B | Page 19 of 44
DAC A and DAC B outputs can be configured to give a voltage
output proportional to the temperature of the internal and
external temperature sensors, respectively.
The dual serial interface defaults to the I
up. To select and lock in the SPI protocol, follow the selection
process as described in the Serial Interface Selection section.
The I
is automatically locked in on selection. The interface can be
switched back to be I
off and on. When using I
V
There are a number of different operating modes on the
ADT7516/ADT7517/ADT7519 devices and all of them can be
controlled by the configuration registers. These features consist
of enabling and disabling interrupts, polarity of the INT/ INT
pin, enabling and disabling the averaging on the measurement
channels SMBus timeout, and software reset.
POWER-UP CALIBRATION
It is recommended that no communication to the part be
initiated until approximately 5 ms after V
within 10% of its final value. It is generally accepted that most
systems take a maximum of 50 ms to power up. Power-up time
is directly related to the amount of decoupling on the voltage
supply line.
During the 5 ms after V
calibration routine. Any communication to the device during
calibration interrupts this routine, and can cause erroneous
temperature measurements. If it is not possible to have V
nominal value by the time 50 ms has elapsed or if communication
to the device has started prior to V
that a measurement be taken on the V
temperature measurement is taken. The V
used to calibrate out any temperature measurement error due to
different supply voltage values.
CONVERSION SPEED
The internal oscillator circuit used by the ADC has the capability
to output two different clock frequencies. This means that the
ADC is capable of running at two different speeds when doing a
conversion on a measurement channel. Thus, the time taken to
perform a conversion on a channel can be reduced by setting
Bit C0 of the Control Configuration 3 register (Address 0x1A).
This increases the ADC clock speed from 1.4 kHz to 22 kHz. At
the higher clock speed, the analog filters on the D+ and D–
input pins (external temperature sensors) are switched off. This
is why the power-up default setting is to have the ADC working
at the slow speed. The typical times for fast and slow ADC
speeds are given in the Specifications section.
DD
or GND.
2
C protocol cannot be locked in, though the SPI protocol
ADT7516/ADT7517/ADT7519
2
C on selection when the device is powered
DD
2
C, the CS pin should be tied to either
has settled, the part is performing a
DD
settling, it is recommended
DD
2
channel before a
C protocol on power-
DD
DD
has settled to
measurement is
DD
at its