Supply Voltage Discrepancy

[RoyAaron]

I am looking to buy a "LM1875 Power Amplifier Board Mono 30W Single Channel Power Supply DC 12-32V" from:
https://www.ebay.com/itm/4043921736...I77mj/p|tkp:Bk9SR7S4hoakZQ&LH_ItemCondition=3
As you can see, it is advertised as requiring 12-32 VDC. But the spec sheet on the LM1875 reads: "Wide Supply Range 16V-60V."
How can they change what the IC requires?

 

[Mooly]

The IC will probably function at 12 volts but also likely not meet its specs in one or more areas. You are correct though, they are specifying a non valid lower voltage.

Also although the LM1875 can deliver 'up to 30 watts' you need to consider the supply voltage used and the load impedance. At 32 volts DC it might manage -/+13 volts output which is just 10 wrms into 8 ohms and 20 wrms into 4 ohm.

 

[RoyAaron]

thank you.
i would be supplying the module with 15VDC, just a tad under the stated requirement.
I was mainly concerned that there's no diode in the IC that cuts out the circuit if it doesn't see 16V.
But a lower output wattage doesn't bother me too much.

 

[Mooly]

There won't be an issue at 15 volts. All that happens as you reduce the supply is that the performance will deviate from the data sheet values, bias current may drop, distortion increase and so on. Eventually it would reach a point where it becomes unusable if you kept reducing the supply.

Output wattage is totally dependent on supply voltage and the load impedance.

 

[RoyAaron]

got it, thank you

 

[Mark Tillotson]

As you can see, it is advertised as requiring 12-32 VDC. But the spec sheet on the LM1875 reads: "Wide Supply Range 16V-60V."

Well you actually see the capacitors are 35V rated from that photo, so the 32V limit is clearly designed in.

 

[RoyAaron]

thank you. i was actually concerned over the lower value. i'll be able to use my 15VDC supply, just with lower output.