Question to MC34708 Silicon revision 2.4

[Mr_Pothill]

We have made an design and prototypes for a i.MX53 with Power Management IC MC34708VM with following information at the BGA packaged top ”DBTBTW1203J”. It is produced in March 2012 and I think It is a Silicon Revision P2.4?

When I read out the IC and Version Identification register 0x07 I get HEX value 14 and it match the Datasheet MC34708 Rev. 8 from the 8/1012 in table 102. (IC Revision Bit Assignment) and this is translate to Silicon Revision P2.4.

If it is true the silicon revision is 2.4, will this silicon revision continues with the same functionality as it do today or will there come a new silicon revision 2.x there match the new updated datasheet from the august 2012.

The reason to I am a little confused, is in the new updated datasheet Rev 8. The Coulomb counter is not longer supported as the charger.
And the pin named BATTISNSCCP and BATTISNSCCN have to be No Connect!

But at our prototype board have we done some test at the Coulomb counter and looks to work okay, so the question is what is the exactly problem with the Coulomb counter? And will it continue as now in the future silicon revision?

In the next prototype have we updated our design with an external Battery charger, but still like to use the input battery monitoring for voltage and current measurement and also the Coulomb counter if possible.

How to configure the MC34708 correct with use external Battery charger?

• BATT and CHRGFB have to be connected together, but it is a connection to battery or Battery charger output (VCC_BP)?
• ITRIC can be floating (No Connect)
• GBAT connect to GND
• BP and BPSNS is connected to Battery charger output (VCC_BP)

Hope somebody have a good answer to my questions

Thanks  

[Mr_Pothill]

Hi Jorge

Thanks for your nice answers. We will continue with the MC34708 device because of two reasons, our tight schedule to finish product and we like to continue design with a 0.8 pitch BGA.
But it is possible we will choose the MC34709 for a future design, with more time to finish product and option for implement this PMIC in the first prototype.

My question is about this configuration of the PMIC is correct?

The VCC_BP is generated from the output of the external battery charger and connected to BATT, CHRGFB, BP and PBSNS at the PMIC. The battery current flows only through the Coulomb counter (Not supported) pins BATTISNSCCN via resistor R434 to BATTISNSCCP and through the BATTISNSN (Battery Voltage measurement via ADC input channel 0) again via resistor R433 to the BATTISNSP (Battery Current measurement via ADC input channel 1 “BATTISNSN- BATTISNSP”).

It's correct the PMIC will continue works okay in this configuration, and we still can monitor the battery voltage and current measurement?

/Thanks

[JorgeRama_rezRi]

Hi Benjamin,

Ok. Yes, the only thing left in your schematic above is to connect BP and BATT to BATTISNSCCN. Besides that it looks fine.

I've just got the news that there's an app note on how to configure the MC34708 for external charger operation under development. I'll let you know as soon as it's ready.

Best regards.

Jorge.

[JorgeRama_rezRi]

Hi Benjamin,

I think I understand what you need now. I believe the only thing left in your diagram above is to connect BP to BATT. Let me analyze it deeper and I'll send you my comments asap.

Best regards.

Jorge.

[JorgeRama_rezRi · Accepted solution]

Hi Benjamin,

The battery charger and coulomb counter are still there in all versions of silicon, but these blocks won't be supported in any of them anymore, that's why they were removed from the datasheet. The coulomb counter has an errata (please see errata file in the web page), so we are recommending to use a SW workaround using the ADC, unfortunately, there's no example code for this workaround yet. For new designs as your next prototype that has an external battery charger, we recommend the MC34709, which is a smaller version of the 34708, and its cost is lower too. The specs are already in the web site.

Hope this helps!

Best regards.

Jorge.