Datasheet

TMC236/A/B DATA SHEET (V2.10 / 2016-Jun-06) 19

Slope Control Resistor

The output-voltage slope of the full bridge outputs can be controlled to reduce noise on the power

supply and on the motor lines and thus electromagnetic emission of the circuit. It is controlled by an

external resistor at the SLP pin.

Operational range:

0k  R

SLP

 100k

The SLP-pin can directly be connected to AGND for the fastest output-voltage slope (respectively

maximum output current). In most applications a minimum external resistance of 10 K is

recommended to avoid unnecessary high switching spikes.

Only for non-A-types the slope on the lower transistors is fixed (corresponding to a 5K to 10K slope

control resistor). For applications where electromagnetic emission is very critical, it might be necessary

to add additional LC (or capacitor only) filtering on the motor connections.

For these applications emission is lower, if only slow decay operation is used.

Please remark, that there is a tradeoff between reduced electromagnetic emissions (slow slope) and

high efficiency because of low dynamic losses (fast slope).

The following table and graph depict typical behavior measured from 15% of output voltage to 85% of

output voltage. However, the actual values measured in an application depend on multiple parameters

and may stray in a user application.

Example for slope settings

SLP

typ.

SLP

30ns

2.2K

60ns

10K

110ns

22K

245ns

51K

460ns

100K

100

SLP

[ns] @ 10V

SLP

in KOhm

10520 20 50 100

SLP

[ns] @ 24V

200

500