MAX6581TG9A+ Maxim Integrated Products, MAX6581TG9A+ Datasheet - Page 10

• Manufacturer Part Number: MAX6581TG9A+
• Description: Board Mount Temperature Sensors 1 C ACCUR 8-CH TEMP SENSR
• Manufacturer: Maxim Integrated Products

Specifications of MAX6581TG9A+

• Full Temp Accuracy: +/- 1 C
• Package / Case: TQFN-24
• Digital Output - Bus Interface: I2C
• Digital Output - Number Of Bits: 11 bit
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 3 V
• Description/function: Multichannel Temperature Sensor
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Supply Current: 4 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

±1°C Accurate 8-Channel Temperature Sensor
From a software perspective, the MAX6581 appears
as a series of 8-bit registers that contain temperature-
measurement data, alarm threshold values, and control
bits. A standard SMBus-compatible, 2-wire serial inter-
face is used to read temperature data and write control
bits and alarm threshold data. The same SMBus slave
address also provides access to all functions.
The MAX6581 employs four standard SMBus proto-
cols: write byte, read byte, send byte, and receive byte
(Figure 2). The shorter receive-byte protocol allows
quicker transfers, provided that the correct data regis-
ter was previously selected by a read-byte instruction.
Use caution with the shorter protocols in multimaster
systems, since a second master could overwrite the
command byte without informing the first master. Figure
Figure 2. SMBus Protocols
10
_____________________________________________________________________________________
WRITE-BYTE FORMAT
READ-BYTE FORMAT
SEND-BYTE FORMAT
S
S
S = START CONDITION
P = STOP CONDITION
S
SLAVE ADDRESS: EQUIVALENT
TO CHIP SELECT LINE
ADDRESS
ADDRESS
7 BITS
7 BITS
SLAVE ADDRESS: EQUIVALENT
TO CHIP-SELECT LINE OF
A 3-WIRE INTERFACE
ADDRESS
7 BITS
WR
WR
SHADED = SLAVE TRANSMISSION
/// = NOT ACKNOWLEDGED
SMBus Digital Interface
ACK
ACK
WR
COMMAND BYTE: SENDS COMMAND
WITH NO DATA, USUALLY
USED FOR ONE-SHOT COMMAND
COMMAND BYTE: SELECTS
WHICH REGISTER YOU ARE
READING FROM
COMMAND
COMMAND
8 BITS
8 BITS
ACK
ACK
ACK
P
COMMAND
8 BITS
S
3 is the SMBus write timing diagram and Figure 4 is the
SMBus read timing diagram.
The remote-diode-measurement channels provide
11 bits of data (1 LSB = 0.125NC). The eight most
significant bits (MSBs) can be read from the local tem-
perature and remote temperature registers. The remain-
ing 3 bits for remote can be read from the extended
temperature register. If extended resolution is desired,
the extended-resolution register should be read first.
This prevents the MSBs from being overwritten by new
conversion results until they have been read. If the MSBs
have not been read within a SMBus timeout period (nom-
inally 37ms), normal updating continues. Table 1 shows
the main temperature register (high-byte) data format
and Table 2 shows the extended-resolution register (low-
byte) data format.
RECEIVE-BYTE FORMAT
SLAVE ADDRESS: REPEATED
DUE TO CHANGE IN DATA-
FLOW DIRECTION
S
ADDRESS
7 BITS
ADDRESS
7 BITS
ACK
RD
DATA BYTE: DATA GOES INTO THE REGISTER
SET BY THE COMMAND BYTE (TO SET
THRESHOLDS, CONFIGURATION MASKS, AND
SAMPLING RATE)
RD
DATA
8 BITS
ACK
ACK
DATA BYTE: READS FROM
THE REGISTER SET BY THE
COMMAND BYTE
DATA BYTE: READS DATA FROM
THE REGISTER COMMANDED
BY THE LAST READ-BYTE OR
WRITE-BYTE TRANSMISSION;
ALSO USED FOR SMBus ALERT
RESPONSE RETURN ADDRESS
DATA
8 BITS
DATA
8 BITS
ACK
///
///
P
1
P
P