ADT7463 Analog Devices, ADT7463 Datasheet - Page 2

• Manufacturer Part Number: ADT7463
• Description: Dbcool Thermal Management Controller And Voltage Monitor
• Manufacturer: Analog Devices

AN-613
system. The mechanical or thermal engineer who is
tasked with the actual system evaluation should also be
involved at the beginning of the process.
AUTOMATIC FAN CONTROL OVERVIEW
Figure 1 gives a top-level overview of the automatic fan
control circuitry on the ADT7460/ADT7463. From a sys-
tems level perspective, up to three system temperatures
can be monitored and used to control three PWM out-
puts. The three PWM outputs can be used to control up
to four fans. The ADT7460/ADT7463 allow the speed of
four fans to be monitored. Each temperature channel
has a thermal calibration block. This allows the
designer to individually configure the thermal character-
istics of each temperature channel. For example, one
may decide to run the CPU fan when CPU temperature
increases above 60°C, and a chassis fan when the local
temperature increases above 45°C. Note that at this
stage, you have not assigned these thermal calibration
settings to a particular fan drive (PWM) channel. The
right side of the Block Diagram (Figure 1) shows controls
that are fan-specific. The designer has individual control
over parameters such as minimum PWM duty cycle, fan
speed failure thresholds, and even ramp control of the
PWM outputs. This ultimately allows graceful fan speed
changes that are less perceptible to the system user.
STEP 1: DETERMINING THE HARDWARE CONFIGURATION
During system design, the motherboard sensing and
control capabilities should not be an afterthought, but
AMBIENT TEMP
REMOTE 1 =
REMOTE 2 =
VRM TEMP
CPU TEMP
LOCAL =
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
MIN
MIN
MIN
T
RANGE
T
T
RANGE
RANGE
Figure 2. Hardware Configuration Example
100%
100%
0%
100%
0%
0%
MUX
PWM
MIN
PWM
–2–
MIN
PWM
MIN
TACHOMETER 1
MEASUREMENT
RAMP CONTROL
ENHANCEMENT)
RAMP CONTROL
RAMP CONTROL
ENHANCEMENT)
ENHANCEMENT)
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
(ACOUSTIC
addressed early in the design stages. Decisions about
how these capabilities are used should involve the sys-
tem thermal/mechanical engineer. Ask the following
questions:
1. What ADT7460/ADT7463 functionality will be used?
2. How many fans will be supported in system, three or
3. Is the CPU fan to be controlled using the ADT7460/
(ACOUSTIC
(ACOUSTIC
• PWM2 or SMBALERT?
• 2.5 V voltage monitoring or SMBALERT?
• 2.5 V voltage monitoring or processor power
• TACH4 fan speed measurement or over-
• 5 V voltage monitoring or overtemperature
• 12 V voltage monitoring or VID5 input?
The ADT7460/ADT7463 offers multifunctional pins that
can be reconfigured to suit different system require-
ments and physical layouts. These multifunction pins
are software programmable. Various pinout options
are discussed in a separate application note.
four? This will influence the choice of whether to use
the TACH4 pin or to reconfigure it for the THERM
function.
ADT7463 or will it run at full speed 100% of the time?
If run at 100%, it will free up a PWM output, but the
system will be louder.
AND 4
monitoring?
temperature THERM function?
THERM function?
GENERATOR
GENERATOR
GENERATOR
CONFIG
PWM
CONFIG
CONFIG
PWM
PWM
PWM
PWM
PWM
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
CPU
FAN SINK
FRONT
CHASSIS
REAR
CHASSIS
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