MAX6615AEE+ Maxim Integrated Products, MAX6615AEE+ Datasheet - Page 15

• Manufacturer Part Number: MAX6615AEE+
• Description: IC TEMP MONITOR DL-CH 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6615AEE+

• 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: 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
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

zero, the duty cycle is zero below the fan-start tempera-
ture and has this value when the fan-start temperature
is reached. A value of 240 represents 100% duty cycle.
Writing any value greater than 240 causes the fan
speed to be set to 100%. The POR state of the fan-start
duty-cycle register is 60h, 40%.
The PWM maximum duty-cycle register sets the maxi-
mum allowable PWM duty cycle between 2/240 (0.83%
duty cycle) and 240/240 (100% duty cycle). Any values
greater than 240 are recognized as 100% maximum
duty cycle. The POR state of the PWM maximum duty-
cycle register is F0h, 100%. In manual-control mode,
this register is ignored.
In automatic fan-control mode, this register contains the
present value of the target PWM duty cycle, as deter-
mined by the measured temperature and the duty-
cycle step size. The actual duty cycle requires time
before it equals the target duty cycle if the duty-cycle
rate-of-change register is set to a value other than zero.
In manual fan-control mode, write the desired value of
the PWM duty cycle directly into this register. The POR
state of the fan-target duty-cycle register is 00h.
These registers always contain the duty cycle of the
PWM signals presented at the PWM output.
The POR state of the PWM instantaneous duty-cycle
register is 00h.
These registers contain the temperatures 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 channel 1
and channel 2 fan-start temperature registers is 00h.
The fan-configuration register controls the hysteresis
level, temperature step size, and whether the remote or
local diode controls the PWM2 signal (see Table 3). 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 hys-
teresis 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. Bits
D5 to D2 select which PWM_ channel 1 or channel 2
controls (see Table 3). If both are selected for a given
PWM_, the highest PWM value is used. If neither is
selected, the fan is controlled by the value written to the
Channel 1 and Channel 2 Fan-Start Temperature
Fan-Speed Controllers with Thermistor Inputs
PWM2 Instantaneous Duty Cycle (0Dh, 0Eh)
PWMOUT Max Duty Cycle (09h and 0Ah)
PWM Target Duty Cycle (0Bh and 0Ch)
______________________________________________________________________________________
Dual-Channel Temperature Monitors and
PWM1 Instantaneous Duty Cycle,
Fan Configuration (11h)
(0Fh and 10h)
fan-target duty-cycle register. Also in this mode, the value
written to the target duty-cycle register is not limited by
the value in the maximum duty-cycle register. It is, howev-
er, clipped to 240 if a value above 240 is written. The
POR state of the fan-configuration register is 00h.
Bits D7, D6, and D5 (channel 1) and D4, D3, and D2
(channel 2) 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 5). 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, and D5 (channel 1) or D4, D3, and D2
(channel 2) = 000. The POR state of the duty-cycle rate-
of-change register is B4h (1s between increments).
Table 5. Setting the Time Between Duty-
Cycle Increments
Table 6. Setting the Duty-Cycle Step Size
D7:D4, D3:D0
D7:D5, D4:D2
0000
0001
0010
0011
0100
0101
1000
1111
000
001
010
011
100
101
110
111
…
...
CHANGE IN DUTY
INCREMENTS (s)
TEMPERATURE
TIME BETWEEN
Duty-Cycle Rate of Change (12h)
CYCLE PER
10/240
16/240
31/240
0.0625
STEP
2/240
4/240
6/240
8/240
0.125
0.25
0.5
…
...
0
0
1
2
4
RANGE FOR FAN
TIME FROM 33%
TEMPERATURE
(1°C STEP, 33%
TO 100% (s)
CONTROL
TO 100%)
160
320
80
40
27
20
16
10
10
20
40
80
...
...
0
5
0
5
15