Control Systems
OBR Control Systems Inc
OBR Control Systems Inc
Telephone : +1 (248) 672-3339
32233 West 8 Mile Road
www.obrcontrolsystems.com
Livonia, Michigan 48152
USA
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9.3 Low Power PWM Outputs
This section gives access to:
Naming of output
Set inrush current threshold
Set time interval for inrush current
Set the normal fused threshold
Set the number of retries once a fault is detected before switching off
Set the time interval for fault resetting
Select the type of PWM applied
Define duty cycle or frequency map
4 low power outputs are available with PWM capability applying frequencies from 30 Hz up to 25
kHz and of supplying a maximum, recommended continuous current of 13..25 A each channel.
Please observe that our default maximum current level for each channel is set in accordance with
Deutsch’s current limit for the size AWG20 contacts in the Autosport 20-39 connector.
The driver stages can deliver significantly more current, but it is important to avoid overloading the
wiring and contacts in the connector.
WARNING: Do NOT connect any PWM output in parallel with any other output!
9.3.1 Half Bridge – Full Bridge
These PWM outputs are true half bridge drivers, having a top and bottom transistor.
Contrary to conventional outputs the PWM outputs are connected to ground when switched off.
By combining 2 PWM outputs you can create a full bridge which for example could be used to drive
a DC motor, turning it clockwise or anti clockwise. In this example you connect one PWM output to
one of the DC motor terminals, a second PWM output to the other DC motor terminal. Depending
on which output you activate you can make the DC motor rotate.
You can configure the PWM drivers as either digital outputs or as frequency, duty cycle controlled
outputs. In this configuration you will be able to control the speed at which the motor rotates.
The control can be extended to included position control via an analogue or digital input or by the
current draw.
9.3.2 Current Draws
Current draws can be measured on all outputs and displays the maximum current draw, neglecting
the OFF periods.
Outputs are protected by three current thresholds and three timers:
- OCH is the high current threshold of typical 75 A.
- OCL is the user defined continuous current threshold, selectable between 7.5 A to 25 A.
- OCS is the software selected current threshold.
