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How to check a L298/L297 circuit ?

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Newbie level 2
Feb 23, 2006
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I just finished making the L298/L297 Circuit for a Bipolar 2-Phase stepper motor... But before hooking it up with my microcontroller circuit i want to check n make sure the circuit is working fine... How do i check it and what should be the voltages on the output of the L298 and what should be the voltages on the Clock,Enable,CW/CCW and Reset pins of the L297...

I connected the chips to 5V and the Vdd of L298 to 30V and I am getting around 6V on the above mentioned pins of the L297 (It would be safe to connect it to a uC?) and on two outputs of L298 I am getting 0V and 17V on the other two...
Why 17V? Should it be this way...?
Secondly i wanted to know which wires of the stepper motor would go into the four outputs? Does the order matter... as when i change the configuration the voltages on the output change....


Added after 5 hours 32 minutes:

Here's the circuit.. Is something wrong or missing?
What should be the output on the four outputs of the L298?

l298 circuit

Everything looks fine but you should put least
470uF 63V and 100nf 63V capacitors between +30V and gnd..
298 has pwm output so you cant see 30V at output
Connect all control pins to uContoller over 100 ohm resistor
PS: 297/298pair are for 4 leads bipolar stepper motors..


l298 l297


i'm designing the same schematic,

I read in the datasheet that the CONTROL pin of the L297 should be connected to VCC if we need to activate A,B,C,D outputs and GND for /INH1 and /INH2, does this mean that :

if we have an unipolar stepper motor----> connect CONTROL to GND
if we have an bi-polar stepper motor----> connect CONTROL to VCC

I have another question, how should we choose the RC values that we connect to the OSC pin (L297) , same thing for Resistor of Vref ?? (are them necessary ?? :|)

thanks in advance.

l297 schematic

Hi, i have used L298 in simulation and in real. i have posted the config i used. and it worked perfect. and i just used 4 diodes. not more.

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