Datasheet

ADT7301
Rev. 0 | Page 14 of 16
ADT7301-to-ADSP-21xx Interface
Figure 18 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:
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
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. On the
ADSP-21xx interface, the TFS and RFS of the SPORT are tied
together; TFS is set as an output, and RFS is set as an input. The
DSP operates in alternate framing mode and the SPORT control
register is set up as described in this section.
ADT7301*
SCLK
DOUT
DIN
ADSP-21xx*
SCK
DR
DT
RFS
02884-0-011
*ADDITIONAL PINS OMITTED FOR CLARITY
TFS
CS
Figure 18. ADT7301-to-ADSP-21 Interface
MOUNTING THE ADT7301
The ADT7301 can be used for surface or air temperature
sensing applications. If the device is cemented to a surface with
a thermally conductive adhesive, the die temperature will be
within about 0.1°C of the surface temperature because of the
ADT7301’s low power consumption. Care should be taken to
insulate the back and leads of the device if the ambient air
temperature is different from the surface temperature being
measured.
The ground pin provides the best thermal path to the die;
therefore the temperature of the die is close to that of the
printed circuit ground track. Care should be taken to ensure
that this is in good thermal contact with the measured surface.
As in 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
The ADT7301 should be decoupled with a 0.1 μF ceramic
capacitor between V
DD
and GND. This is particularly important
if the ADT7301 mount is remote from the power supply.