SmartFan^®Vortex

Operation

Remote Sensor Selection (J7)
When configured to operate with a remote external temperature sensor, choose a compatible SmartFan Sensor shown in the SmartFan Catalog at www.controlres.com/sensors.php. Control temperature is set through the I2C Bus.

Board-Mounted Temperature Sensor
In this application, fan voltage is proportional to the temperature at the sensor that is soldered to the Vortex. Control temperature is set through the I2C Bus

Fan Tachometer Setting
Since fan tachometer circuits are designed with one, two or even more pulse outputs per revolution, settings are listed in pulses per minute (PPM) rather than revolutions per minute (RPM). Given the fan’s speed under load (W) and the number of pulses per revolution (N), use the following formula to select the trigger speed (W_A):

W_A = W x N x 0.3

For example, a 3300-RPM fan with two pulses per revolution would have a trigger speed of

W_A = 3300 RPM x 2PPR x 0.3 = 1980 PPM.

Since the 2000 PPM trigger is closest, set tachometer speed to 2000 PPM.
The alarm trigger accuracy is +/- 20%.
The Vortex default factory setting is 2000 PPM.

On-Board Isolated Power Setting (J6)
The Vortex provides 3.3 or 5.0 VDC power for the I2C Bus interface. Use header J6 to select the power required. Move the shunt to 3.3 if 3.3 VDC power is required. Move the shunt to 5.0 if 5.0 VDC power is required.

Led Output Status Operation (J8)
Both normally on (green) and normally off (red) LED outputs are provided. Two leaded and three leaded (common Cathode) Bi-colored LEDs can also be used.

Alarm Logic (J7 – Pin A)
A single Alarm output is provided on J7. The output is set to VCC when there is no alarm and Ground during any alarm condition. The output is current limited by a 600 Ohm drive impedance.

Fan Voltage in any Alarm Condition
During the presence of any alarm condition, the full supply voltage is applied to the fans.

Speed Override Input (J7 – Pin S)
A non-isolated input is located at J7 that allows the user to command the fans to full speed when a ground level is applied. If this input is set to VCC or open then the speed is set by its normal operating mode. Refer to Figure 1 (in the Installation page) for wiring details.

I2C BUS PROTOCOL

The I2C Bus is configured as a slave device that can transmit and receive data. When the Vortex is configured for I2C based speed control, the user can write speed commands to the Vortex and read all alarm status bits. When configured for temperature based control the user can read all alarm status bits from the Vortex. Writing an I2C speed command changes the control mode from temperature based to I2C based.

Specifications

• The bus supports seven-bit addressing and only acts as a slave device.
• The address for the fan controller is 0x0C (‘0001100’) when the ID pin is pulled low. The address for the fan controller is 0x0D (‘0001101’) when the ID pin is pulled high or floating.
• General call support is not provided.
• The fan controller will stretch the clock further if needed. The I2C master must observe clock stretching.
• The hardware register will support Standard Mode I2C with speeds up to 100 KHz, however, lower clock speeds are recommended for increased noise immunity.
• If temperature control mode is disabled and I2C speed mode is used, then I2C communication must occur within ~2 minutes of the last communication, or there will be an I2C communication timeout error. When an I2C timeout occurs, full supply voltage will be applied to the fans, and fan speed must be reset with a new speed command. Performing any valid I2C operation on a bus will clear the timeout condition and restart the watchdog timer.
• Fan failure based on 2000 minimum PPM of fan in slow (default) mode or 4000 minimum PPM in fast mode. Fan failure is not updated when the output is set to 0 VDC.
• It is possible for noise to cause the I2C hardware to miss an address or data. In this case an Ack will not be generated. The production tester allows 3 errors to occur before marking the board as failing. Also during the EEPROM write cycle the I2C will not generate ACK signals as no more data can be accepted until the write cycle is complete. Typical write cycle is 8ms.

Table 3.0 defines the bits used in the serial bus protocol.

Write sequence

S A6 A5 A4 A3 A2 A1 A0 W Ack L7 L6 L5 L4 L3 L2 L1 L0 Ack D7 D6 D5 D4 D3 D2 D1 D0 Ack P

Read sequence

S A6 A5 A4 A3 A2 A1 A0 W Ack L7 L6 L5 L4 L3 L2 L1 L0 Ack P S A6 A5 A4 A3 A2 A1 A0 R Ack D7 D6 D5 D4 D3 D2 D1 D0 Ack P

Register Locations: L7-L0 Label (R/W) [initial condition]

Register 0x00 – 0xEF: Generic EEPROM storage (Read/Write) [undetermined]

Register 0xF0: Firmware Revision (Read only) [00:current rev]

Register 0xF4: Current Target Speed (Read only) [0000 1100]
D0-7: 0x0C = 12 VDC, 0x06 = 6VDC
(Commanded speed with alarm status override included)
(In temperature mode this register will read 0x0C)

Register 0xF5: Current Speed (Read only) [0000 1100]
D0-7: 0x0C = 12 VDC, 0x06 = 6VDC
(What the actual current voltage is)
(In temperature mode this register will read 0x0C)

Register 0xF6: Commanded Speed (Read/Write) [1111 1111]

D0-3: 0x0C = 12 VDC, 0x06 = 6VDC
(0x00 = off, all others = approximate DC voltage applied)
If set to 0xFF then temperature mode is enabled and I2C speed control disabled

Register 0xF7: Off Temperature (Read/Write) [1111 1111]
D0-7: Temperature from 0 - 70 in degrees C in 0.5 deg steps
Temperature below which the controller turns off the fan output (0 VDC)
If set to 0xFF then function disabled

Register 0xF8: Control Temperature (Read/Write) [0101 0000]
D0-7: Temperature from 0 - 70 in degrees C in 0.5 deg steps
Full speed temperature, only used if Commanded Speed set to 0xFF.

Register 0xF9: Alarm Temperature (Read/Write) [1111 1111]
D0-7: Temperature from 0 - 70 in degrees C in 0.5 deg steps
Temperature above which the controller alarms
If set to 0xFF then function disabled

Register 0xFB-0xFF: CRI Test Register (Reserved) [xxxx xxxx]
D0-7: Do not use

Note: If a fan failure occurs the Current Speed will be updated to 12V but the Commanded Speed will remain at its previous value. Once the failure clears the Current Speed will return to the Commanded Speed value. An I2C timeout changes BOTH the Current Speed and Commanded Speed to 12V. The Commanded Speed must be reset after a timeout. During the speed ramp the Current Speed will not match the Commanded Speed until the ramp completes.