ADT7301

Preliminary Technical Data

Rev. PrJ | Page 12 of 14

ADT7301 to ADSP-21xx Interface

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:

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. 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.

ADT7301*

SCLK

DOUT

DIN

ADSP-21xx*

SCK

DR

DT

RFS

*ADDITIONAL PINS OMITTED FOR CLARITY

TFS

CS

Figure 17. 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

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.

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.

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

The ADT7301 should be decoupled with a 0.1 µF ceramic

if the ADT7301 is mounted remote from the power supply.