MAX6664AEE+ Maxim Integrated Products, MAX6664AEE+ Datasheet - Page 11

• Manufacturer Part Number: MAX6664AEE+
• Description: IC TEMP MON FAN CNTRL 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6664AEE+

• 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

Table 9. Setting PWM Duty Cycle
Automatic fan-speed control is selected by setting bits
[7:5] of configuration register 1 (00h) to 100 (to control
speed based on the remote temperature) or 101 (to
control speed based on both remote and local temper-
ature). Program a threshold, or starting temperature
TMIN, and the desired temperature range, T
the local temp T
temperature and into the remote temp T
register (25h) for remote temperature (Tables 10 and
11). If the fan control responds to both local and remote
temperatures, the higher PWM duty cycle has priority.
Table 10. T
Range Bits [2:0] T
(24h and 25h)—POR = 001
BIT 3
BIT 2
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
CONFIGURATION REGISTER (22h)
0
0
0
0
1
BITS [3:0] OF FAN-SPEED
BIT 2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
RANGE
BIT 1
0
0
1
1
0
MIN
______________________________________________________________________________________
BIT 1
/T
MIN
Fan-Control Temperature
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
RANGE
Automatic Fan-Control Mode
BIT 0
/T
0
1
0
1
0
RANGE
register (24h) for local
BIT 0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
TEMPERATURE
Registers
RANGE (°C)
MIN
CYCLE (%)
10
20
40
80
RANGE
5
% DUTY
/T
100
14
20
27
33
40
47
53
60
67
73
80
87
93
0
7
RANGE
, into
Temperature Monitors and
When the temperature exceeds T
enabled at a minimum duty cycle programmed in bits
[3:0] of the fan-speed configuration register (22h). The
duty cycle increases in proportion to the temperature
difference and reaches 100% at a temperature equal to
(T
T
ping when the temperature is at the set point.
To ensure proper fan startup, the MAX6653/MAX6663/
MAX6664 can be set to drive the fan to 100% duty
cycle for a short period on startup, and then revert to
the correct duty cycle. The spin-up time is programmed
by bits [2:0] in the fan characteristics register (20h).
The spin-up feature can be disabled by setting bit 7 of
the fan-filter register (23h) to 1; POR value is zero.
Table 12 shows programming of the spin-up time.
When the MAX6653/MAX6663/MAX6664 are used for
automatic fan-speed control, the fan-filter mode helps
minimize the audible effects of varying fan speeds. The
fan-filter mode limits the rate at which fan speed can
change. Each time a new temperature measurement is
made, the fan-filter mode allows the PWM duty cycle to
increment by a selectable amount. The duty cycle can
change by 1/240, 2/240, 4/240, or 8/240 (0.416%,
0.833%, 1.667%, or 3.333%) of the PWM period after
each temperature-monitoring cycle. This prevents sud-
den changes in fan speed, even when temperature
changes suddenly.
The filter mode is set by bit 0 of the fan-filter register
(23h). To enable the fan-filter mode, write a 1 to this bit.
Bits [6:5] of the same register control the size of the
PWM steps.
Note that the rate of change depends on both the value
selected by the fan-filter bits and on the temperature
Table 11.T
Temperature; Bits [7:3] T
Registers (24h—POR = 01000 and
25h—POR = 01100
MSB = +64°C
MIN
MIN
BIT 7
PWM Fan Controllers
set point to prevent the fan from starting and stop-
+ T
RANGE
MIN
BIT 6
). A hysteresis of 5°C is built into the
Max threshold = +127°C
POR = +48°C or 01100b
LSB/step size = +4°C
Min threshold = 0°C
Fan-Control Start
BIT5
MIN
BIT 4
Fan-Filter Mode
/T
MIN
RANGE
, the fan is
LSB = +4°C
Spin-Up
BIT3
11