Author Topic: SPD3303X-E Ripple Voltage  (Read 206 times)

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Offline syTopic starter

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SPD3303X-E Ripple Voltage
« on: January 02, 2025, 09:51:41 am »
Hi, I've just been playing around with building some circuits when I noticed the ripple voltage of my power supply seemed to be quite high.
I've tried testing it with a 18Ohm 10W resistor (that's the largest power resistor I have), and with no decoupling capacitors, the maximum ripple voltage at 9V 0.5A is about 220mVpk-pk.
I've looked online and they've said around 1% tolerance is generally acceptable, however, the ripple is around 2.4%.
I'm not sure how concerned I should be, however, when I add a 10uF capacitor it drops to around 50mVpk-pk which gives 0.5% ripple.
I guess my question is what is an acceptable variation in the regulated voltage from a switching power supply and should I be concerned?
 

Offline syTopic starter

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Re: SPD3303X-E Ripple Voltage
« Reply #1 on: January 02, 2025, 11:19:11 am »
Just adding on to this, the datasheet specifies the accuracy to be "Voltage: ± (0.5% of reading + 2 digits)".
If I've set it at 9V, then I should be seeing: Vpk-pk = (9*0.005 + 2 digits) * 2 = 0.130Vpk-pk ripple -- however, I am seeing almost twice this value?
 

Offline PGPG

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Re: SPD3303X-E Ripple Voltage
« Reply #2 on: January 02, 2025, 12:27:01 pm »
Try to be more precise in what you are writing.

when I noticed the ripple voltage of my power supply seemed to be quite high.

I understand you sow ripple at oscilloscope.

I've looked online and they've said around 1% tolerance is generally acceptable, however, the ripple is around 2.4%.

What tolerance?
Supply average output voltage tolerance? It has nothing to ripple.
Supplied by you device tolerance to supply voltage change? Ripple is peak to peak so it is +1.2% and -1.2%.

I'm not sure how concerned I should be,

You said absolutely nothing about device you are supplying.
If that device is just blinking LED generator than even 1V ripple at 9V supply will be OK.

Just adding on to this, the datasheet specifies the accuracy to be "Voltage: ± (0.5% of reading + 2 digits)".

At that place I don't know how you measure your ripple. Do you use some digital multimeter?

Edit later:
After posting I noticed that there is SPD3303X-E in title. May be searching a net for it will give me some guess what your posts are about.
« Last Edit: January 02, 2025, 12:30:01 pm by PGPG »
 


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