MAX1669 Datasheet, PDF (7/20 Pages) Maxim Integrated Products – Fan Controller and Remote Temperature Sensor with SMBus Serial Interface

Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
V_CC
DXP
DXN
MUX
ADC
GND
COMMAND-BYTE
(INDEX) REGISTER
8
REMOTE-TEMPERATURE
DATA REGISTER
8
HIGH-TEMPERATURE
THRESHOLD
LOW-TEMPERATURE
THRESHOLD
8
DIGITAL COMPARATOR
TEMPERATURE SENSOR
I/O1
GENERAL-PURPOSE
I/O CONTROLLER
I/O2
-5°C
TEMPERATURE
T_CRIT
CONTROL
LOGIC
ADDRESS
ADD0
ADD1
DECODER
ADD2
SMB
READ WRITE
8
8
SMBDATA
SMBCLK
CONFIGURATION
BYTE REGISTER
STATUS BYTE REGISTER
MAX1669
ALERT RESPONSE
ADDRESS REGISTER
R
S
Q
CONTROL
LOGIC
ALERT
R
Q ^CONTROL
S
LOGIC
OVERT
Figure 1. MAX1669 Temperature Sensor Functional Diagram
_______________Detailed Description
The MAX1669 temperature sensor is designed to work
with an external microcontroller (µC) or other intelligent
devices in computer fan-control applications. The µC is
typically a power-management or keyboard controller,
generating SMBus serial commands by “bit-banging’’
general-purpose input/output (GPIO) pins or through a
dedicated SMBus interface block.
Essentially an 8-bit serial analog-to-digital converter
(ADC) with a sophisticated front end, the temperature
measurement channel contains a switched-current
source, a multiplexer, and an integrating ADC.
Temperature data from the ADC is loaded into a data
register, where it is automatically compared with data
previously stored in over/undertemperature alarm regis-
ters and the critical register (Figure 1).
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