Datasheet

TMC2300 DATASHEET (Rev. 1.02 / 2019-NOV-06) 59
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16 External Reset
The chip is loaded with default values during power on via its internal power-on reset. In order to
reset the chip to power on defaults, any of the supply voltages monitored by internal reset circuitry
(VS or VCC_IO) must be cycled. It is easiest and safest to cycle VCC_IO in order to completely reset the
chip. Also, current consumed from VCC_IO is low and therefore it has simple driving requirements.
Due to the input protection diodes not allowing the digital inputs to rise above VCC_IO level, all
inputs must be driven low during this reset operation. When this is not possible, an input protection
resistor may be used to limit current flowing into the related inputs.
17 Clock Oscillator
The clock is the timing reference for all functions: the chopper frequency, the blank time, the standstill
power down timing, and the internal step pulse generator etc. The on-chip clock oscillator is not
calibrated, but relatively temperature-stable. The internal clock frequency is roughly 12MHz. When the
internal pulse generator is used, and increased precision is desired, measure the internal frequency by
doing a test-motion (with motor disabled) and adapt the pulse frequency to the actual value of the
frequency. Store the calibration value into the microcontroller’s EEPROM for the application.