LM95245EB/NOPB National Semiconductor, LM95245EB/NOPB Datasheet - Page 14

• Manufacturer Part Number: LM95245EB/NOPB
• Description: BOARD EVALUATION FOR LM95245
• Manufacturer: National Semiconductor
• Series: PowerWise®, TruTherm®r

Specifications of LM95245EB/NOPB

• Sensor Type: Temperature
• Sensing Range: -40°C ~ 125°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1°C
• Voltage - Supply: 3 V ~ 3.6 V
• Embedded: No
• Utilized Ic / Part: LM95245
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM95245EB

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The data registers in the LM95245 are selected by the Com-
mand Register. At power-up the Command Register is set to
“00”, the location for the Read Local Temperature Register.
The Command Register latches the last location it was set to.
Each data register in the LM95245 falls into one of four types
of user accessibility:
1.
2.
3.
4.
A Write to the LM95245 will always include the address byte
and the command byte. A write to any register requires one
data byte.
Reading the LM95245 can take place either of two ways:
1.
2.
The data byte has the most significant bit first. At the end of
a read, the LM95245 can accept either acknowledge or No
Acknowledge from the Master (No Acknowledge is typically
used as a signal for the slave that the Master has read its last
byte). When retrieving all 11 bits from a previous remote diode
temperature measurement, the master must insure that all 11
bits are from the same temperature conversion. This may be
achieved by reading the MSB register first. The LSB will be
Read only
Write only
Write/Read same address
Write/Read different address
If the location latched in the Command Register is correct
(most of the time it is expected that the Command
Register will point to one of the Read Temperature
Registers because that will be the data most frequently
read from the LM95245), then the read can simply
consist of an address byte, followed by retrieving the data
byte.
If the Command Register needs to be set, then an
address byte, command byte, repeat start, and another
address byte will accomplish a read.
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locked after the MSB is read. The LSB will be unlocked after
being read. If the user reads MSBs consecutively, each time
the MSB is read, the LSB associated with that temperature
will be locked in and override the previous LSB value locked-
in.
1.11 SERIAL INTERFACE RESET
In the event that the SMBus Master is RESET while the
LM95245 is transmitting on the SMBDAT line, the LM95245
must be returned to a known state in the communication pro-
tocol. This may be done in one of two ways:
1.
2.
1.12 ONE-SHOT CONVERSION
The One-Shot register is used to initiate a single conversion
and comparison cycle when the device is in standby mode,
after which the device returns to standby. This is not a data
register and it is the write operation that causes the one-shot
conversion. The data written to this address is irrelevant and
is not stored. A zero will always be read from this register.
When SMBDAT is LOW, the LM95245 SMBus state
machine resets to the SMBus idle state if either SMBDAT
or SMBCLK are held low for more than 35 ms (t
Note that according to SMBus specification 2.0 all
devices are to timeout when either the SMBCLK or
SMBDAT lines are held low for 25 - 35 ms. Therefore, to
insure a timeout of all devices on the bus the SMBCLK
or SMBDAT lines must be held low for at least 35 ms.
When SMBDAT is HIGH, have the master initiate an
SMBus start. The LM95245 will respond properly to an
SMBus start condition at any point during the
communication. After the start the LM95245 will expect
an SMBus Address address byte.
TIMEOUT
).