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Input Power: The Vortex accepts a 12 VDC (+/-20%) power
source and can supply up to 5.0 Amps to the fan load with
natural convection at 12 VDC.
Fan Speed Control: The speed of all fans is varied by adjusting
the fan voltage. Voltage adjustment is accomplished with a
current mode buck-only control circuit. The fan voltage range is
0-12 VDC for 12 VDC fans.
Input Power Fuse: A 7.5 Amp re-settable input power fuse is
provided to protect the Vortex from over-current conditions.
Soft Start: The voltage applied to the fans at start-up ramps
from 0 to 12 VDC for 12 VDC fans. After this period, the fan
voltage moves to the commanded voltage. This “soft start”
feature limits the current spike common to DC fans at start-up.
Number of Fans: The Vortex can be configured to power and
monitor 1 to 4 fans.
Fan Control Methods: Two methods of controlling the speed of
the fans are settable via the I2C Bus: Temperature Sensor
(thermistor) input or I2C Bus input. Following is a description
of each control method:
1) Temperature Based Fan Control: The speed of all fans is
proportional to the temperature sensor connected to header J7, or
the temperature of the board mounted sensor. Chart 1.0 shows
fan voltage as a function of sensed temperature. I2C Bus
register 0xF8 is used to set the control temperature, TC (The
control temperature is the temperature at which full supply
voltage is applied to the fans.). Temperature sensor status and
temperature readings are available on the I2C Bus.
2) I2C Bus Based Fan Control: When an I2C speed command
is given, the Vortex automatically switches to I2C control mode
for fan control via the I2C Bus. The speed of all fans is mapped
to the command sent through the I2C on header J7. See the
Operation Section for a full definition of the I2C protocol.
Chart 1: Fan voltage vs sensor temperature examples (5 deg slope)
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Number of Temperature Sensors: When temperature sensor
based fan control is specified, the user can choose to control
based on the remotely mounted sensor or the board mounted
sensor.
Selectable Control Temperature and Slope: When
temperature sensor based fan control is specified, the user can
set the control temperature and choose a 5°C or 10°C slope via
the I2C Bus.
Selectable Off Temperature: When temperature sensor based
fan control is specified, the user can select an off temperature
which will set the fan voltage to 0 VDC when the temperature
drops below the set point.
Selectable Alarm Temperature: When temperature sensor
based fan control is specified, the user can set the alarm
temperature. When the temperature exceeds the alarm
temperature, an alarm is triggered and full supply voltage is
applied to the fans.
On Board Power Supply: 3.3 or 5.0 VDC power to run the I2C
Bus can be selected by the jumper setting on J6. The Vortex
uses a common negative ground for all power and signal
connections.
Standard Configuration of the Vortex
The Vortex is intended to be configured via an I2C Bus. If no
I2C Bus is connected the Vortex will default to temperature
based speed control as follows.
- Assumes four fans are connected
- Temperature is monitored by the remote sensor
- Control (full speed) temperature is 40ºC
- Temperature slope is 5ºC
- Idle speed (temperature below 35ºC) is ~13 VDC
- Fan alarm is set at 2000 PPM with 4 fans connected
- Over temperature alarm is disabled
- LED and Cmos outputs are active for fan alarms and
external sensor failure (open)
If your system does not utilize an I2C Bus and the temperature
control parameters above do not meet your needs, the Vortex can
be configured at the factory for special temperature control
parameters. Contact Control Resources’ application engineering
for assistance.
Specialized Configurations of the Vortex
The following parameters can be specialized through software
modification:
- Relationship between sensed temperature and fan
voltage
- Fan speed control based on differential temperature
- Fan speed alarm trigger point
- I2C Bus status register
Customized Configuration of the Vortex
Contact Control Resources’ application engineering with special
or custom requirements.
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