cat34ts02 ON Semiconductor, cat34ts02 Datasheet - Page 4

• Manufacturer Part Number: cat34ts02
• Description: Digital Output Temperature Sensor With On-board Spd Eeprom
• Manufacturer: ON Semiconductor

CAT34TS02
PIN DESCRIPTION
SCL: The Serial Clock input pin accepts the Serial
Clock generated by the Master (Host).
SDA: The Serial Data I/O pin receives input data
and transmits data stored in the internal registers. In
transmit mode, this pin is open drain. Data is
acquired on the positive edge, and is delivered on
the negative edge of SCL.
A0, A1 and A2: The Address pins set the device
address. These pins have on-chip pull-down
resistors and will default to an address of 000 if left
unconnected.
¯¯¯¯¯¯ : The open-drain EVENT
EVENT
programmed to signal over/under temperature limit
conditions.
POWER-ON RESET (POR)
The CAT34TS02 incorporates Power-On Reset
(POR) circuitry which monitors the supply voltage,
and then resets (initializes) the internal state
machines below (above) a POR trigger level of
approximately 1.2 V, i.e. well below the minimum
recommended V
The TS component will power-up into conversion
mode, while the SPD EEPROM component will
power-up into Standby mode.
The internal state machines will operate properly
above the POR trigger level, but valid temperature
readings can be expected only after the first
conversion cycle under nominal bias conditions.
DEVICE INTERFACE
The CAT34TS02 supports the Inter-Integrated
Circuit (I
(SMBus)
protocols describe serial communication between
transmitters and receivers sharing a 2-wire data bus.
Data flow is controlled by a Master device, which
generates the serial clock and the START and
STOP conditions. The CAT34TS02 acts as a Slave
device. Master and Slave alternate as transmitter
and receiver. Up to 8 CAT34TS02 devices may be
present on the bus simultaneously, and can be
individually addressed by matching the logic state of
the address inputs A0, A1, and A2.
Doc. No. MD-1129 Rev. C
2
C) and the System Management Bus
data
CC
transmission
value.
¯¯¯¯¯¯ pin can be
protocols.
These
4
I
The I
and one for data (SDA). The two wires are
connected to the V
Master and Slave devices connect to the bus via
their respective SCL and SDA pins. The transmitting
device pulls down the SDA line to ‘transmit’ a ‘0’ and
releases it to ‘transmit’ a ‘1’.
Data transfer may be initiated only when the bus is
not busy (see A.C. Characteristics).
During data transfer, the SDA line must remain
stable while the SCL line is HIGH. An SDA transition
while SCL is HIGH will be interpreted as a START or
STOP condition (Figure 1).
START
The START condition precedes all commands. It
consists of a HIGH to LOW transition on SDA while
SCL is HIGH. The START acts as a ‘wake-up’ call to
all Slaves. Absent a START, a Slave will not
respond to commands.
STOP
The STOP condition completes all commands. It
consists of a LOW to HIGH transition on SDA while
SCL is HIGH. The STOP tells the Slave that no more
data will be written to or read from the Slave.
DEVICE ADDRESSING
The Master initiates data transfer by creating a START
condition on the bus. The Master then broadcasts an
8-bit serial Slave address. The first 4 bits of the Slave
address (the preamble) select either the Temperature
Sensor (TS) registers (0011) or the EEPROM memory
contents (1010), as shown in Figure 2. The next 3 bits,
A2, A1 and A0, select one of 8 possible Slave devices.
The last bit, R/W ¯ ¯ , specifies whether a Read (1) or
Write (0) operation is being performed
ACKNOWLEDGE
A matching Slave address is acknowledged (ACK)
by the Slave by pulling down the SDA line during the
9
acknowledge all data bytes sent to the bus by the
Master. When the Slave is the transmitter, the
Master will in turn acknowledge data bytes in the 9
clock cycle. The Slave will stop transmitting after the
Master
(NoACK) and then issues a STOP. Bus timing is
illustrated in Figure 4.
2
th
C/SMBUS PROTOCOL
clock cycle (Figure 3). After that, the Slave will
2
C/SMBus uses two ‘wires’, one for clock (SCL)
does
not
CC
respond
supply via pull-up resistors.
Characteristics subject to change without notice
© 2008 SCILLC. All rights reserved.
with
acknowledge
th