TMC246_06 Datasheet, PDF(11/26 Page) List of Unclassifed Manufacturers – High Current Microstep Stepper Motor Driver with sensorless stall detection, protection / diagnosis and SPI Interface

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TMC246_06 Datasheet, PDF (11/26 Pages) List of Unclassifed Manufacturers – High Current Microstep Stepper Motor Driver with sensorless stall detection, protection / diagnosis and SPI Interface

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TMC246 / TMC246A DATA SHEET (V2.03 / Nov. 6th, 2006)

Open load detection

Open load is signaled, whenever there are more than 14 oscillator cycles without PWM switch off.

Note that open load detection is not possible while coil current is set to â0000â, because the chopper is

off in this condition. The open load flag will then always be read as inactive (â0â). During overcurrent

and undervoltage or overtemperature conditions, the open load flags also become active!

Due to their principle, the open load flags not only signal an open load condition, but also a torque loss

of the motor, especially at high motor velocities. To detect only an interruption of the connection to the

motor, it is advised to evaluate the flags during stand still or during low velocities only (e.g. for the first

or last steps of a movement).

Standby and shutdown mode

The circuit can be put into a low power standby mode by the user, or, automatically goes to standby

on Vcc undervoltage conditions. Before entering standby mode, the TMC246 switches off all power

driver outputs. In standby mode the oscillator becomes disabled and the oscillator pin is held at a low

state. The standby mode is available via the interface in SPI-mode and via the ENN pin in non-SPI

mode.

The shutdown mode even reduces supply current further. It can only be entered in SPI-mode by

pulling the ENN pin high. In shutdown additionally all internal reference voltages become switched off

and the SPI circuit is held in reset.

Power saving

The possibility to control the output current can dramatically save energy, reduce heat generation and

increase precision by reducing thermal stress on the motor and attached mechanical components.

Just reduce motor current during stand still: Even a slight reduction of the coil currents to 70% of the

current of the last step of the movement, halves power consumption! In typical applications a 50%

current reduction during stand still is reasonable.

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