ADT7301

Rev. B | 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

*ADDITIONAL PINS OMITTED FOR CLARITY

TFS

CS

Figure 18. ADT7301-to-ADSP-21xx 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

if the ADT7301 mount is remote from the power supply.