MAX6641AUB92+T Maxim Integrated Products, MAX6641AUB92+T Datasheet - Page 11

• Manufacturer Part Number: MAX6641AUB92+T
• Description: IC TEMP MONITOR SMBUS 10UMAX
• Manufacturer: Maxim Integrated Products

Specifications of MAX6641AUB92+T

• Function: Fan Control, Temp Monitor
• Topology: ADC, PWM Generator, Tach Counter
• 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: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Full Temp Accuracy: +/- 4 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 8 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Read the fan instantaneous duty-cycle register to deter-
mine the duty cycle at PWMOUT at any time. The POR
state of the fan instantaneous duty-cycle register is 00h.
These registers contain the temperature threshold val-
ues at which fan control begins in automatic mode. See
the Automatic PWM Duty-Cycle Control section for
details on setting the fan-start thresholds. The POR
state of the remote- and local-diode fan-start tempera-
ture registers is 00h.
The fan-configuration register controls the hysteresis
level, temperature step size, and whether the remote or
local diode controls the PWMOUT signal; see Table 1.
Set bit D7 of the fan-configuration register to zero to set
the hysteresis value to 5 C. Set bit D7 to 1 to set the
hysteresis value to 10 C. Set bit D6 to zero to set the
fan-control temperature step size to 1 C. Set bit D6 to 1
to set the fan-control temperature step size to 2 C. Set
bit D5 to 1 to control the fan with the remote-diode’s
temperature reading. Set bit D4 to 1 to control the fan
with the local-diode’s temperature reading. If both bits
D5 and D4 are high, the device uses the highest PWM
value. If both bits D5 and D4 are zero, the MAX6641
runs in manual fan-control mode where only the value
written to the fan-target duty-cycle register (09h) con-
trols the PWMOUT duty cycle. In manual fan-control
mode, the value written to the fan-target duty-cycle reg-
ister is not limited by the value in the maximum duty-
cycle register. It is, however, clipped to 240 if a value
above 240 is written. The POR state of the fan-configu-
ration register is 00h.
Bits D7, D6, and D5 of the duty-cycle rate-of-change
register set the time between increments of the duty
cycle. Each increment is 2/240 of the duty cycle; see
Table 3. This allows the time from 33% to 100% duty
cycle to be adjusted from 5s to 320s. The rate-of-
change control is always active in manual mode. To
make instant changes, set bits D7, D6, D5 = 000. The
POR state of the duty-cycle rate-of-change register is
A0h (1s time between increments).
Bits D7–D4 of the duty-cycle step-size register change
the size of the duty-cycle change for each temperature
step. The POR state of the duty-cycle step-size register
is 50h; see Table 4.
SMBus-Compatible Temperature Monitor with
Fan Instantaneous Duty Cycle (0Ah)
______________________________________________________________________________________
Fan-Start Temperature (0Bh, 0Ch)
Duty-Cycle Rate of Change (0Eh)
Automatic PWM Fan-Speed Controller
Duty-Cycle Step Size (0Fh)
Remote- and Local-Diode
Fan Configuration (0Dh)
Set bits D7, D6, and D5 (select A, select B, and select
C) in the PWM frequency-select register to control the
PWMOUT frequency; see Table 5. The POR state of the
PWM frequency select register is 40h, 33Hz. The lower
frequencies are usually used when driving the fan’s
power-supply pin as in the Typical Application Circuit,
with 33Hz being the most common choice. The 35kHz
Table 3. Duty-Cycle Rate-of-Change
Register (0Eh)
Table 4. Duty-Cycle Step-Size
Register (0Fh)
D7–D4
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
D7, D6, D5
000
001
010
011
100
101
110
111
TEMPERATURE STEP
CHANGE IN DUTY
CYCLE PER
10/240
12/240
14/240
16/240
18/240
20/240
22/240
24/240
26/240
28/240
30/240
0/240
2/240
4/240
6/240
8/240
INCREMENTS (s)
TIME BETWEEN
0.0625
0.1250
0.2500
0.5000
1.0000
2.0000
4.0000
PWM Frequency Select (10h)
0
(1 C STEP, 33% TO 100%)
TEMPERATURE RANGE
FOR FAN CONTROL
TIME FROM 33%
TO 100% (s)
80.00
40.00
26.67
20.00
16.00
13.33
11.43
10.00
8.89
8.00
7.27
6.67
6.15
5.71
5.33
N/A
160
320
10
20
40
80
0
5
11