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ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsLM73CIMK-1/NOPB
11121314151617181920
D7 D6 D5 D4 D3 D2 D1 D0
1 9 1 9
Ack
by
LM73
Start by
Master
NoAck
by
Master
SMBCLK
SMBDAT
Stop
by
Master
R/W
0 1 A2 A0
1 0
A1
1 9
D15 D14 D13 D12 D11 D10 D9 D8
Ack
by
Master
Frame 1
Serial Bus Address Byte
Frame 2
Data Byte from LM73
Frame 3
Data Byte from LM73
LM73
SNIS141D –OCTOBER 2005–REVISED MAY 2009
www.ti.com
COMMUNICATING WITH THE LM73
The data registers in the LM73 are selected by the Pointer Register. At power-up the Pointer Register is set to
“00h”, the location for the Temperature Register. The Pointer Register latches the last location it was set to. Note
that all Pointer Register bits are decoded; any incorrect pointer values will not be acknowledged and will not be
stored in the Pointer Register.
NOTE
A write to an invalid pointer address is not allowed. If the master writes an invalid address
to the Pointer Register,
1. the LM73 will not acknowledge the address and
2. the Pointer Register will continue to contain the last value stored in it.
A Write to the LM73 will always include the address byte and the pointer byte.
A Read from the LM73 can take place either of two ways:
1. If the location latched in the Pointer Register is correct (that is, the Pointer Register is pre-set prior to the
read), then the read can simply consist of an address byte, followed by retrieving the data byte. Most of the
time it is expected that the Pointer Register will point to Temperature Registers because that will be the data
most frequently read from the LM73.
2. If the Pointer Register needs to be set, then an address byte, pointer byte, repeat start, and another address
byte will accomplish a read.
The data byte is read out of the LM73 by the most significant bit first. At the end of a read, the LM73 can accept
either an Acknowledge or No Acknowledge bit from the Master. No Acknowledge is typically used as a signal to
the slave that the Master has read its last byte.
(a) Typical Read from a 2-Byte Register with Preset Pointer
(b) Typical Pointer Set Followed by Immediate Read of a 2-Byte Register
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