Data Sheet

Use of Safety Contactor for Critical Applications

GDC3xxx Motor Controller Datasheet 5

Precautions and Optional Connections

Note 1: Backup battery to ensure motor operation with weak or discharged batteries, con-

nect a second battery to the Power Control wire/terminal via the SW1 switch.

Note 2: Use precharge 1K, 0.5W Resistor to prevent switch arcing.

Note 3: Insert a high-current diode to ensure a return path to the battery during regenera-

tion in case the fuse is blown.

Note 4: Optionally ground the VMot tabs when the controller is Off if there is any concern

that the motors could be made to spin and generate voltage in excess of 60V.

Note 5: Connect the controller’s bottom plate to a wire connected to the Earth while the

charger is plugged in the AC main, or if the controller is powered by an AC power supply.

Note 6: Beware not to create a path from the ground pins on the I/O connector and the

battery minus terminal.

Use of Safety Contactor for Critical Applications

An external safety contactor must be used in any application where damage to property or

injury to person can occur because of uncontrolled motor operation resulting from failure

in the controller’s power output stage.

PwrCtrl

SW1 Main

On/Off Switch 1A

Diode

>20A

Resistor

1K, 0.5W

I/O Connector

VMot

to +40V Max

Digital Out

Ground

Main

Battery

FIGURE 1.Contactor wiring diagram

FIGURE 3. Contactor Wiring Diagram

The contactor coil must be connected to a digital output conﬁgured to activate when

“No MOSFET Failure”. The controller will automatically deactivate the coil if the output is

expected to be off and battery current of 1A or more is measured for more than 0.5s. This

circuit will not protect against other sources of failure such as those described in the “Im-

portant Safety Disclaimer” on Page3.