---
title: "PWM-controlled mode"
slug: "pwm-controlled-mode"
updated: 2024-07-04T11:10:29Z
published: 2024-07-04T11:10:30Z
canonical: "docs-linescan.alliedvision.com/pwm-controlled-mode"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs-linescan.alliedvision.com/llms.txt
> Use this file to discover all available pages before exploring further.

# PWM-controlled mode

In the PWM-controlled mode the output currents of the XLC4 control unit are set and adjusted by two external opto-isolated input signals, ON and PWC.

| Parameter | Value |
| --- | --- |
| cuPar.WorkingMode | 2 |

The LEDs are switched on with a high level at input ON and are switched off with a low level.

The current for the 4 channels are controlled by the duty cycle of the PWC input.

## Resulting output current

PWC is a pulse-width-modulated signal. The duty cycle of PWC defines a current factor F. F is multiplied with the default channel current of each individual channel to set the resulting output current:

I(channel) = Idefault(channel) × F

### Duty cycle D

The duty cycle D ist defined as D = tP/T

![](https://cdn.document360.io/eca58697-9c2f-461e-9f0a-e6205b74b693/Images/Documentation/image(12).png)Duty cycle D

### Current factor F

The current factor F is defined:

| F(PWC) = D(PWC)/0.8 | for 0.1 ≤ D(PWC) ≤ 0.8 |
| --- | --- |
| F(PWC) = 1 | for D(PWC) > 0.8 |

![](https://cdn.document360.io/eca58697-9c2f-461e-9f0a-e6205b74b693/Images/Documentation/image(13).png)

### Pulse width tP and pulse period T

The base currents Idefault(channel) are read from cuPar.DefaultCurrent[0..3].

The following limits are valid for tP and T:

| Item | Description | Min | Nominal | Max | Unit |
| --- | --- | --- | --- | --- | --- |
| tP | pulse width (high) | 10 |  | 100 | µs |
| T | pulse period | 20 |  | 250 | µs |

Additional condition: tP ≥ 0.1 × T