Servo control operation, Current command input, Chapter 4: servo control operation – ElmoMC SimplIQ Analog Servo Amplifiers-Violin Installation User Manual

Page 17: 1 current command input, 2 cfm

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Violin Installation Guide

MAN-VIOIG (Ver. 2.3)

4-1

Chapter 4: Servo Control Operation

4.1

Current Command Input

The Violin has 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:

R

in (KΩ)

= (5.33 * V

in

) - 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.

4.2 CFM

The amplifier is equipped with a current feedback multiplier (CFM). Connecting pin
J1/10 to J1/8 multiplies the signal of the current feedback by 2 and consequently causes
the following changes to occur:

Current gains are divided by 2
Current monitor is multiplied by 2
Current limits are divided by 2

This function should be activated whenever the rated current and the peak current of the
motor are less than 50% of the amplifier rated continuous and peak limits, respectively.


Continuous
Current limit


Peak Current
Limit


Current
Gain(A/V)

Current
Monitor
(V/A)

Differential
Input
Impedance

Without CFM Ic

Ip

Ip/3.75

3.9/Ip

40 kΩ

With CFM

Ic/2

Ip/2

Ip/7.5

7.8/Ip

40 kΩ

Table 4-1: CFM Effects

The default (pin J1/10 left open) is the low current feedback.
For permanent selection, a simple short is recommended.
For remote selection, the scheme in

Figure

4-1

should be used.

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