TMP512 datasheet(16/62 Pages) TI2

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TMP512

TMP513

SBOS491A

– JUNE 2010 – REVISED MAY 2011

www.ti.com

Data transfer is then initiated and eight bits of data

WRITING TO/READING FROM THE

are sent, followed by an Acknowledge bit. During

TMP512/13

data transfer, SDA must remain stable while SCL is

Accessing a particular register on the TMP512/13 is

HIGH. Any change in SDA while SCL is HIGH is

accomplished by writing the appropriate value to the

interpreted as a START or STOP condition.

Once all data have been transferred, the master

registers and corresponding addresses. The value for

generates a STOP condition, indicated by pulling

the register pointer as shown in Figure 26 is the first

SDA from LOW to HIGH while SCL is HIGH. The

byte transferred after the slave address byte with the

TMP512/13 includes a 28ms timeout on its interface

R/W

bit

LOW.

Every

write

operation

the

to prevent locking up an SMBus.

TMP512/13 requires a value for the register pointer.

Writing to a register begins with the first byte

SERIAL BUS ADDRESS

transmitted by the master. This byte is the slave

address, with the R/W bit LOW. The TMP512/13 then

To communicate with the TMP512/13, the master

acknowledge receipt of a valid address. The next

must first address slave devices via a slave address

byte transmitted by the master is the address of the

byte. The slave address byte consists of seven

address bits, and a direction bit indicating the intent

address value updates the register pointer to the

of executing a read or write operation.

desired register. The next two bytes are written to the

The TMP512/13 feature an address pin to allow up to

four devices to be addressed on a single bus. Table 1

TMP512/13 acknowledge receipt of each data byte.

describes the pin logic levels used to properly

The

master

may

terminate

data

transfer

connect up to four devices. The state of the A0 pin is

generating a START or STOP condition.

sampled on every bus communication and should be

When reading from the TMP512/13, the last value

set before any activity on the interface occurs. The

stored in the register pointer by a write operation

address

read

the

start

each

determines which register is read during a read

communication event.

operation. To change the register pointer for a read

operation, a new value must be written to the register

Table 1. TMP512/13 Address Pins and

Slave Addresses

pointer. This write is accomplished by issuing a slave

address byte with the R/W bit LOW, followed by the

DEVICE TWO-WIRE

ADDRESS

A0 PIN CONNECTION

The master then generates a START condition and

1011100

Ground

sends the slave address byte with the R/W bit HIGH

1011101

V+

to initiate the read command. The next byte is

1011110

SDA

transmitted by the slave and is the most significant

byte of the register indicated by the register pointer.

1011111

SCL

This byte is followed by an Acknowledge from the

master; then the slave transmits the least significant

SERIAL INTERFACE

byte. The master acknowledges receipt of the data

The TMP512/13 operate only as slave devices on the

byte. The master may terminate data transfer by

two-wire bus and SMBus. SCL is an input only, and

generating a Not-Acknowledge after receiving any

TMP512/13 cannot drive it. Connections to the bus

data byte, or generating a START or STOP condition.

are made via the open-drain I/O lines SDA and SCL.

If repeated reads from the same register are desired,

The SDA and SCL pins feature integrated spike

it is not necessary to continually send the register

suppression filters and Schmitt triggers to minimize

pointer bytes; the TMP512/13 retain the register

the effects of input spikes and bus noise. The

pointer value until it is changed by the next write

TMP512/13 support the transmission protocol for fast

operation.

(1kHz to 400kHz) and high-speed (1kHz to 3.4MHz)

Figure 24 and Figure 25 show read and write

modes. All data bytes are transmitted MSB first.

operation timing diagrams, respectively. Note that

followed by the least significant byte. See Figure 27

for

illustration

typical

pointer

configuration.

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