Power Supply Related to AFT05MP075N

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Power Supply Related to AFT05MP075N

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Contributor I

Hello,

I want to know detail, when I use AFT05MPO74N design my products.

(1) I do not know  the value of VBIAS and VSUPPLY in Figure11 on page 10 of Document1?

(2)  Do I need to add cooling fan for AFT05MPO74N, if I use the reference design in Doctument2?

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NXP TechSupport

1.
Datasheet provides amplifier performance when VSUPPLY equals to either 12.5V or 13.6V as shown in Figures 12..16.

VBIAS should be tuned to set required quiescent current. Datasheet provides performance for IDQ(A+B)=500mA.
Actual bias voltage can vary from device to device and on the required quiescent current. It will be above the threshold voltage that is specified as [1.7min;2.1typ;2.5max]V.

2.
Amplifier requires cooling: heat sink and/or fan.

Power efficiency is about 70% at maximum power. The dissipation power is 75W*(1/70%-1) = 32W. To keep case temperature below 80'C, the thermal resistance of the heat sink should be less than (80'C max -30'C ambient)/32W = 1.5'C/W.

Passive heat sink can be used as well, but it's size is determined by required thermal resistance. Rough estimation is 500-800 cm^3 per 1'C/W. So, a passive heat sink volume should be at least 340-540 cm^3. For example, 10cm*10cm*5cm.Have a great day,

Pavel
TIC

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3 Replies
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Contributor I

Thanks a lot!!

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Contributor I
• I have some questions like you，can you give me your email
36 Views
NXP TechSupport

1.
Datasheet provides amplifier performance when VSUPPLY equals to either 12.5V or 13.6V as shown in Figures 12..16.

VBIAS should be tuned to set required quiescent current. Datasheet provides performance for IDQ(A+B)=500mA.
Actual bias voltage can vary from device to device and on the required quiescent current. It will be above the threshold voltage that is specified as [1.7min;2.1typ;2.5max]V.

2.
Amplifier requires cooling: heat sink and/or fan.

Power efficiency is about 70% at maximum power. The dissipation power is 75W*(1/70%-1) = 32W. To keep case temperature below 80'C, the thermal resistance of the heat sink should be less than (80'C max -30'C ambient)/32W = 1.5'C/W.

Passive heat sink can be used as well, but it's size is determined by required thermal resistance. Rough estimation is 500-800 cm^3 per 1'C/W. So, a passive heat sink volume should be at least 340-540 cm^3. For example, 10cm*10cm*5cm.Have a great day,

Pavel
TIC

-------------------------------------------------------------------------------
Note:
- If this post answers your question, please click the "Mark Correct" button. Thank you!

- We are following threads for 7 weeks after the last post, later replies are ignored
Please open a new thread and refer to the closed one, if you have a related question at a later point in time.