ADT73±1
Preliminary Technical Data
ADT7301 to ADSP-21xx Interface
MOUNTING THE ADT7301
Figure 17 shows an interface between the ADT7301 and the
ADSP-21xx DSP processor. To ensure correct operation of the
interface, the SPORT control register should be set up as
follows:
The ADT7301 can be used for surface- or air-temperature
sensing applications. If the device is cemented to a surface with
thermally conductive adhesive, the die temperature will be
within about 0.1°C of the surface temperature, thanks to the
ADT7301’s low power consumption. Care should be taken to
insulate the back and leads of the device from the air if the
ambient air temperature is different from the surface tempera-
ture being measured.
TFSW = RFSW = 1, alternate framing
INVRFS = INVTFS = 1, active low framing signal
DTYPE = 00, right justify data
SLEN = 1111, 16-bit data-words
ISCLK = 1, internal serial clock
The ground pin provides the best thermal path to the die, so the
temperature of the die will be close to that of the printed circuit
ground track. Care should be taken to ensure that this is in
good thermal contact with the surface being measured.
TFSR = RFS = 1, frame every word
IRFS = 0, RFS configured as input
ITFS = 1, TFS configured as output
The interface requires an inverter between the SCLK line of the
ADSP-21xx and the SCLK input of the ADT7301. The ADSP-
21xx has the TFS and RFS of the SPORT tied together, with TFS
set as an output and RFS set as an input. The DSP operates in
alternate framing mode, and the SPORT control register is set
up as described previously.
As with any IC, the ADT7301 and its associated wiring and
circuits must be kept free from moisture to prevent leakage and
corrosion, particularly in cold conditions where condensation is
more likely to occur. Water-resistant varnishes and conformal
coatings can be used for protection. The small size of the
ADT7301 allows it to be mounted inside sealed metal probes,
which provide a safe environment for the device.
SUPPLY DECOUPLING
ADSP-21xx*
SCK
ADT7301*
SCLK
The ADT7301 should be decoupled with a 0.1 µF ceramic
capacitor between VDD and GND. This is particularly important
if the ADT7301 is mounted remote from the power supply.
DR
DOUT
DIN
DT
CS
RFS
TFS
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 17. ADT7301 to ADSP-21 Interface
Rev. PrJ | Page 12 of 14