ATMEL ATM90E26 shunt value selection

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Hi,

 

We have designed a custom board for ATM90E26 energy ic based on the reference design as mention in the below link

http://www.atmel.com/Images/Atmel-46102-SE-M90E26-ApplicationNote.pdf

 

We are using shunt based configuration with value as 0.002Ohm, but the problem is, when we apply power source to 

the circuit, as mention (designator in reference design 330nF) C6 and C8 are shorted and burnt. Can you please suggest

me, which component we have to replace to proper operation of the circuit ?

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Last Edited: Tue. Feb 9, 2016 - 09:38 AM
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I think you've wired up the board seriously wrong! C6 and C8 are only low voltage capacitors and don't expect to have much voltage across them. Realise that the earth symbol on the schematic is tied to active, so it is not really earth! If you tied that to real earth, then that would explain the capacitors failling.

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Hi Kartman,

 

Thanks for your response.

 

I am new to the energy metering, can you please explain the above scenario. Actually I am confused with the Ground and Earth on the the board.

I am attaching the schematic design of my circuit, can you please explain with reference to circuit ?

 

Last Edited: Fri. Jan 8, 2016 - 11:35 AM
This reply has been marked as the solution. 
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On the Atmel board, your mgnd is tied to active. Thus the voltage across your c9 and c11 is low. You havent tied mgnd to anything, so the voltages will be high. If you're not understanding basic electrical principles, then you're dealing with dangerous circuitry. The design, layout and component choice is critical to safety. So stop, analyse and understand what you're dealing with before you injure yourself or others.

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I Have the similar circuit, But, when I am trying to read data ( using UART  ) I am getting frequency only. remaining values are zeros.

 

My Configuration is as follows.

Shunt 0.3mOhm, LLine Configuration

 

Software Configuration

REG_CALBR_START written 0x5678

REG_CHECKSUM1 ( 0x2C )- read and written back to same Register

REG_PL_CONST_HIGH (0x21) written  0x00DA

REG_PL_CONST_LOW (0x22) written  0x2E8B

REG_MODE_CONFIGURATION (0x2B) written 0x7422

REG_SMALL_POW_MODE ( 0x04 ) written  0xA987

 

After this LLINE_MEAN_ACTIVE_POWER ( 0x4A ) Register Value Read 5 times

and then METER_CMD_LLINE_MEAN_REACTIVE_POWER ( 0x4B ) Register Value Read 5 Times And accumulated values separately and find the compliment values for the same and written those offset values to METER_CMD_LLINE_ACTIVE_POWER_OFFSET (0x37) and METER_CMD_LLINE_REACTIVE_POWER_OFFSET ( 0x38 ) respectively.

 

REG_LLINE_CALBR_GAIN (0x23)  written 0x1475

REG_LLINE_CALBR_ANGLE (0x24) written 0x0024

REG_ACTIVE_START_POWER_THRES (0x27) written 0x08BD

REG_ACTIVE_NOLOAD_POWER_THRES (0x28) written 0x08BD

REG_REACTIVE_START_POWER_THRES (0x29) written 0x08BD

REG_REACTIVE_NOLOAD_POWER_THRES (0x2A) written 0x08BD

REG_VOLTAGE_RMS_GAIN (0x31) written 0x5C3B

REG_LLINE_CURRENT_RMS_GAIN ( 0x32) written 0x5AA7

REG_SMALL_POW_MODE (0x04) written 0x0110 // to exit from Small Power Mode

REG_CALBR_START (  0x20)  written 0x8765 // to exit from Calibration mode

 

 

After that I have check the Register Values as below

  
0x42 :0x0000
0x43 :0x0000
0x44 :0x0AE1
0x45 :0x0AE1
0x46 :0xF801
0x48 :0x0000
0x49 :0x0000
0x4A :0x0000
0x4B :0x0000
0x4C :0x1405
0x4D :0x0000
0x4E :0x8588
0x4F :0x0000
0x68 :0x0000
0x6A :0x0000
0x6B :0x0000  
0x6D :0x0000
0x6E :0x8176
0x6F :0x0000

 

From the above reading I understand that only frequency Register (0x4C) is giving the proper values.

Am I missing anything in the configuration flow. If yes, please suggest me the flow.

 

 

 

Kisstrnonics

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May I ask a question? What's the test point(CFX) used for,and how?

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The CF1,2 outputs give a pulse per unit of energy methinks.