Synrad Novanta OEM ti Series, User Manual

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48 VDC FAN SPEED CONTROL PAGE | 67
Internal fan speed control
The side-mounted DB-9 connector on SA model lasers has internal circuitry that controls fan speed
based on the laser’s output power and chassis temperature. At tickle, or very low PWM duty cycles,
cooling fans run at reduced speed to minimize noise; at higher PWM duty cycles, fan speed increases to
match the cooling rate to power output. Fan speed is controlled by pulse width modulation (PWM) of
the Fan Power Return lines (Pin 5/Pin 9) as shown in the figure below.
The following figure illustrates the connections for internal fan speed control when using customer-
supplied 48 VDC cooling fans. Connect the positive (+) fan leads to Pin 4 and Pin 8, +48 VDC Fan Power
Output, and connect the negative (–) fan leads to Pin 5 and Pin 9, Fan Power Return.
Some types of cooling fans are not designed for PWM control and will stall at low speeds. NOVANTA has
tested Delta EFB1248SHE cooling fans with good results.
Figure 4-19 Internal fan speed control circuitry.
Important Note: The combined current draw of both (or any two) fans must not exceed 1.0 A to
prevent tripping the internal 1.1 A self-resetting fuse.