Datasheet ADT7302 (Analog Devices) - 10

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ADT7302 01, 0010, 1100, 0000 75°C 00, 1001, 0110, 0000 DIGITAL OUTPUT 00, 0000, 0000, 0001 –0.03125°C 11, 1111, 1111, 1111 TEMPERATURE (°C) –40°C 150°C –30°C 11, 1100, 0100, 0000 11, 1011, 0000, 0000
04662-013 Figure 13. Temperature to Digital Transfer Function
CS t1 t t 2 7 SCLK 1 2 3 4 15 16 t3 t8 t4 DOUT LEADING ZEROS DB13 DB12 DB0 DB1 DB0 t6 t5 POWER-
-014
DIN DOWN
04662 Figure 14. Serial Interface Timing Diagram
SERIAL INTERFACE
The serial interface on the ADT7302 consists of four wires: CS, A read operation from the ADT7302 accesses data from the SCLK, DIN, and DOUT. The interface can be operated in temperature value register while a write operation to the part 3-wire mode with DIN tied to ground, in which case the inter- writes data to the control register. face has read-only capability, with data being read from the data
Read Operation
register via the DOUT line. It is advisable to always use CS to Figure 14 shows the timing diagram for a serial read from the create a communications window, as shown in Figure 13, ADT7302. The CS line enables the SCLK input. Thirteen bits of because this improves synchronization between the ADT7302 and the master device. The DIN line is used to write the part data plus a sign bit are transferred during a read operation. Read operations occur during streams of 16 clock pulses. The into standby mode, if required. The CS line is used to select the first two bits out are leading zeros and the next 14 bits contain device when more than one device is connected to the serial the temperature data. If CS remains low and 16 more SCLK clock and data lines. cycles are applied, the ADT7302 loops around and outputs the The part operates in slave mode and requires an external y two leading zeros plus the 14 bits of data that are in the temper- applied serial clock to the SCLK input to access data from the ature value register. When CS returns high, the DOUT line goes data register. The serial interface on the ADT7302 allows the into three-state. Data is clocked out onto the DOUT line on the part to be interfaced to systems that provide a serial clock falling edge of SCLK. synchronized to the serial data, such as the 80C51, 87C51, 68HC11, 68HC05, and PIC16Cxx microcontrollers as well as DSP processors. Rev. B | Page 10 of 16 Document Outline Features Applications Functional Block Diagram General Description Product Highlights Revision History Specifications Timing Characteristics Absolute Maximum Ratings ESD Caution Pin Configurations and Function Descriptions Typical Performance Characteristics Theory of Operation Converter Details Temperature Value Register Temperature Conversion Equations Serial Interface Read Operation Write Operation Applications Information Microprocessor Interfacing ADT7302 to MC68HC11 Interface ADT7302 to 8051 Interface ADT7302 to PIC16C6x/7x and PIC16F873 Interface ADT7302 to ADSP-21xx Interface Mounting the ADT7302 Supply Decoupling Outline Dimensions Ordering Guide