PMinMo L297-8 bipolar driver resistance watt

[KC Chin]

Hi all,
First time posting message. I have few questions and hope someone can help out.

The BOM for the L297-8 for the Bi-Polar Driver.
1. All the resistors are stated for 1/8W. Can I replace it with 1/4W
2. As for the capacitor, as stated as 10uf 6VDC. The Mouser's part list of 140-L35V10-RC stated as 35VDC. Which is correct value? Can I use 16VDC or 25VDC?

TIA
Regards,
KC Chin. CNC 1st timer

[irving2008]

Originally Posted by KC Chin Hi all, First time posting message. I have few questions and hope someone can help out. The BOM for the L297-8 for the Bi-Polar Driver. 1. All the resistors are stated for 1/8W. Can I replace it with 1/4W 2. As for the capacitor, as stated as 10uf 6VDC. The Mouser's part list of 140-L35V10-RC stated as 35VDC. Which is correct value? Can I use 16VDC or 25VDC? TIA Regards, KC Chin. CNC 1st timer

You can use 1/4w, but some locations are a little tight where the resistor is lying down.

My parts list shows C2 as a 25v capacitor. Its on the 5v rail so anything over 10v is OK, the main thing is to ensure 0.1" lead spacing else it wont fit the board.

If your DC supply is greater than 24v you will need a heatsink on the voltage regulator.

Here are a couple of pictures of one of my boards...



Here is a picture of mine

[KC Chin]

Excellence.

I noticed there is a zener diode at D9 next to L297. The board L297-8 layout don't have any zener diode! The layout, schematic and bom was date 18/1/2009.

Thank for the help.
Cheers,
KC Chin

[irving2008]

Mine is the earlier BOM etc dated 18 July 2007.

There are two versions of the LM317. If you use the AHV version the zener isnt needed as its ok to 60v. However, I found the regulator gets hotter than I like so I have fitted D9 and D10, to drop 5.1v each, as my supply is 36v, that makes the regulator input 26v. That also means I can use the lower spec LM317.

You can also use a resistor in place of the diodes, the current consumption of the L297/298 is around 80mA so a 270ohm 2W resistor (spanning the locations for D9 and D10) would do for a 36v supply but its bigger than the zener and wont fit under the heatsink so easily.

[KC Chin]

Now, I can get my L297-8 bipolar driver done. Hopely within a week or so.
Thank you again.
Cheers,
KC Chin