LAN8720 power consumption

[lpcware]

Content originally posted in LPCWare by madid87 on Fri May 17 07:37:33 MST 2013
Hello.
I'm having trouble with the LAN8720 which is used on lpcxpresso board.

Datasheet states that power consumption should be around 45mA with 100Mbit traffic.

These are my results (ampermeter in series with LAN820 power supply, tested on custom board)
After reset, no cable connected - 42mA
Power Down - 2.5mA
100Mbit operation - 80mA.

It's almost 2x the specified and I noticed that the IC is a little hot.

Is this maybe a mistake in the datasheet and 80mA is normal?

The communication is working properly.

Thank you.

[lpcware]

Content originally posted in LPCWare by R2D2 on Sat May 18 03:01:49 MST 2013

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Quote: madid87
... I must be absolutely sure...

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Then ask SMSC: https://www2.smsc.com/mkt/intforms.nsf/faemail

[lpcware]

Content originally posted in LPCWare by madid87 on Sat May 18 00:00:34 MST 2013

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Quote: R2D2
That's not unusual (and may vary with LED power consumption). At least for my LAN8720 board (with powerful LEDs and a very hot LAN8720).

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Hi.
Thank you for the reply.

The problem is that the current consumption is outside one specified in the datasheets and I must be absolutely sure that the design is correct since I'm working on a commercial product.

Best regards.

[lpcware]

Content originally posted in LPCWare by R2D2 on Fri May 17 18:11:34 MST 2013

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Quote: madid87
After reset, no cable connected - 42mA
Power Down - 2.5mA
100Mbit operation - 80mA.

It's almost 2x the specified and I noticed that the IC is a little hot.

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That's not unusual (and may vary with LED power consumption). At least for my LAN8720 board (with powerful LEDs and a very hot LAN8720).