TMC236 Datasheet, PDF (10/25 Pages) List of Unclassifed Manufacturers – High Current Microstep Stepper Motor Driver with protection / diagnosis and SPI Interface

TMC236/A DATA SHEET (V2.04 / Nov. 6th, 2006)
10
Typical winding current values
Current setting Percentage of
CA3..0 / CB3..0 ^current
0000
0%
0001
6.7%
0010
13.3%
...
...
1110
93.3%
1111
100%
Typical trip voltage of the current sense comparator
(internal reference or analog input voltage of 2V is used)
0 V (bridge continuously in slow decay condition)
23 mV
45 mV
317 mV
340 mV
The current values correspond to a standard 4 Bit DAC, where 100%=15/16. The contents of all
registers is cleared to “0” on power-on reset or disable via the ENN pin, bringing the chip to a low
power standby mode. All SPI inputs have Schmitt-Trigger function.
Base current control via INA and INB in SPI mode
In SPI mode, the IC can use an external reference voltage for each DAC. This allows the adaptation to
different motors. This mode is enabled by tying pin ANN to GND. A 2.0V input voltage gives full scale
current of 100%. In this case, the typical trip voltage of the current sense comparator is determined by
the input voltage and the DAC current setting (see table above) as follows:
V_TRIP,A = 0.17 V_INA × “percentage SPI current setting A”
V_TRIP,B = 0.17 V_INB × “percentage SPI current setting B”
A maximum of 3.0V V_IN is possible. Multiply the percentage of base current setting and the DAC table
to get the overall coil current. It is advised to operate at a high base current setting, to reduce the
effects of noise voltages. This feature allows a high resolution setting of the required motor current
using an external DAC or PWM-DAC (see schematic for examples).
INA
INB
AGND
ANN
using PWM signal
µC-
PWM
47K
100nF
8 level via R2R-DAC
100K
µC-
Port .2
10nF
100K
µC-
Port .1
100K
µC-
Port .0
2 level control
R1
µC-
Port
Controlling the power down mode via the SPI interface
Bit
Standard
function
Control
word
function
11 10 9 8 7 6 5 4 3 2 1 0
MxA CA3 CA2 CA1 CA0 PhA MxB CB3 CB2 CB1 CB0 PhB
- 0000 - - 0000 -
Enable standby mode and
clear error flags
Programming current value “0000” for both coils at a time clears the overcurrent flags and switches
the TMC236 into a low current standby mode with coils switched off.
Copyright © 2004, TRINAMIC Motion Control GmbH & Co KG