MAX6653AEE+ Maxim Integrated Products, MAX6653AEE+ Datasheet - Page 6

• Manufacturer Part Number: MAX6653AEE+
• Description: IC TEMP MON FAN CNTRL 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6653AEE+

• Function: Fan Control, Temp Monitor
• Topology: ADC, Multiplexer, Register Bank, Tachometer
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: I²C™/SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Full Temp Accuracy: +/- 1 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 11 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX6653/MAX6663/MAX6664 are local/remote
temperature monitors and fan controllers for micro-
processor-based systems. These devices communi-
cate with the system through a serial SMBus interface.
The serial bus controller features a hard-wired address
pin for device selection, an input line for a serial clock,
and a serial line for reading and writing addresses and
data (see Functional Diagram).
The MAX6653/MAX6663/MAX6664 fan control section
can operate in three modes. In the automatic fan-control
mode, the fan’s power-supply voltage is automatically
adjusted based on temperature. The control algorithm
parameters are programmable to allow optimization to
the characteristics of the fan and the system. RPM select
mode forces the fan speed to a programmed tachome-
ter value. PWM duty cycle select mode allows user
selection of the PWM duty cycle. PWM rise and fall times
are limited to maximize fan reliability.
To ensure overall system reliability, the MAX6653/
MAX6663/MAX6664 feature an SMBus timeout so that
the MAX6653/MAX6663/MAX6664 can never “lock” the
SMBus. Furthermore, the availability of hard-wired
default values for critical temperature set points
ensures the MAX6653 controls critical temperature
events properly even if the SMBus is “locked” by some
other device on the bus.
From a software perspective, the MAX6653/MAX6663/
MAX6664 appear as a set of byte-wide registers. These
devices use a standard SMBus 2-wire/I
serial interface to access the internal registers. The
MAX6653/MAX6663/MAX6664 slave address can be
set to three different values by the input pin ADD
Temperature Monitors and
PWM Fan Controllers
Table 1. MAX6653 Power-Up Set-Point Decoding
6
_______________________________________________________________________________________
CRIT1
Open
Open
Open
GND
GND
GND
V
V
V
CC
CC
CC
Detailed Description
SMBus Digital Interface
CRIT0
Open
Open
Open
GND
GND
GND
V
V
V
CC
CC
CC
2
C-compatible
REMOTE
100
105
110
115
120
125
THERM SET POINT (°C)
85
90
95
(Table 2) and, therefore, a maximum of three MAX6653/
MAX6663/MAX6664 devices can share the same bus.
The MAX6653/MAX6663/MAX6664 employ four stan-
dard SMBus protocols: Write Byte, Read Byte, Send
Byte, and Receive Byte (Figures 1, 2, and 3). The short-
er Receive Byte protocol allows quicker transfers, pro-
vided that the correct data register 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 with-
out informing the first master.
The MAX6653/MAX6663/MAX6664 respond to the
SMBus alert response address, an event which typical-
ly occurs after an SMBus host master detects an INT
interrupt signal going active (referred to as ALERT in
SMBus nomenclature). When the host master puts the
alert response address (0001 1001) on the bus, all
devices with an active INT output respond by putting
their own address onto the bus. The alert response can
activate several different slave devices simultaneously,
similar to the I
attempts to respond, bus arbitration rules apply, and
the device with the lowest address code wins. The
master then services the devices from the lowest
address up.
Table 2. MAX6653/MAX6663/MAX6664
Slave Address Decoding
LOCAL
55
60
65
70
75
80
85
90
95
No connect
ADD PIN
GND
V
CC
2
C general call. If more than one slave
REMOTE
SHUTDOWN SET POINT (°C)
Alert Response Address
120
110
115
125
125
125
125
125
125
ADDRESS
0101 100
0101 110
0101 101
LOCAL
80
85
90
95
95
95
95
95
95