DS75U Datasheet, PDF (10/14 Pages) Maxim Integrated Products – Digital Thermometer and Thermostat

DS75
Table 6. Fault Tolerance Configuration
F1 F0 CONSECUTIVE OUT-OF-LIMITS
CONVERSIONS TO TRIGGER O.S.
00
1
01
2
10
4
11
6
REGISTER POINTER
The four DS75 registers each have a unique two-bit pointer designation, which is defined in Table 7.
When reading from or writing to the DS75, the user must “point” the DS75 to the register that is to be
accessed. When reading from the DS75, once the pointer is set, it will remain pointed at the same register
until it is changed. For example, if the user desires to perform consecutive reads from the temperature
register, then the pointer only has to be set to the temperature register one time, after which all reads will
automatically be from the temperature register until the pointer value is changed. On the other hand,
when writing to the DS75, the pointer value must be refreshed each time a write is performed even if the
same register is being written to twice in a row.
At power-up, the default pointer value is the temperature register so the temperature register can be read
immediately without resetting the pointer.
Changes to the pointer setting are accomplished as described in the 2-WIRE SERIAL DATA BUS section
of this datasheet.
Table 7. POINTER DEFINITION
REGISTER P1 P0
Temperature
00
Configuration
01
T_HYST
10
T_OS
11
2-WIRE SERIAL DATA BUS
The DS75 communicates over a standard bi-directional 2-wire serial data bus that consists of a serial
clock (SCL) signal and serial data (SDA) signal. The DS75 interfaces to the bus via the SCL input pin
and open-drain SDA I/O pin. All communication is MSb first.
The following terminology is used to describe 2-wire communication:
Master Device: Microprocessor/microcontroller that controls the slave devices on the bus. The master
device generates the SCL signal and START and STOP conditions.
Slave: All devices on the bus other than the master. The DS75 always functions as a slave.
Bus Idle or Not Busy: Both SDA and SCL remain high. SDA is held high by a pullup resistor when the
bus is idle, and SCL must either be forced high by the master (if the SCL output is push-pull) or pulled
high by a pullup resistor (if the SCL output is open-drain).
Transmitter: A device (master or slave) that is sending data on the bus.
Receiver: A device (master or slave) that is receiving data from the bus.
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