Dragonfly/Butterfly Installation Guide
Chapter 4: Servo Control Operation
4.1Current Command Input
The Dragonfly and Butterfly have a single differential input. The input operating voltage range is ± 3.75 V, meaning that a 3.75 V signal will result in a fully rated peak current. The current limit circuits will override this signal if the peak duration exceeds 2.7 seconds and/or the required current exceeds the values set by the ECLC and ECLP signals. If the input command voltage exceeds 3.75 V, input scaling must be implemented by adding a pair of external resistors, according to the following formula:
Rin (kΩ) = (5.33 * Vin) - 20
Be careful not to apply input voltage above the maximum allowed input voltage as this will cause the input operational amplifier to operate beyond its limits (±20 V) and in extreme cases, may even damage it.
4.2External Current Limit - Continuous (ECLC)
The continuous current limit of the Dragonfly and Butterfly amplifiers can be scaled down by an external voltage or by an external resistor connected from pin J1/9 (ECLC) to pin J1/8 (ECLRET).
4.2.1External Voltage
IC(new) = | VECLC | * Ic(nom) | |
3.75V | |||
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An external positive voltage (0 to 3.75 V) to terminal J1/9 (ECLC) in reference to terminal J1/8 (ECLRET) will control the continuous current limit from zero to Ic (nom).
The voltage is internally clamped to 3.75 V whenever the external VECLC is greater than 3.75V.
The external voltage source must be able to source/ sink at least ±0.2 mA.
The maximum absolute VECLC allowed to be connected is 5 V.
