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Maxim Integrated - Integration Nation
Mark Fortunato

Tell Me Why My Smartphone Requires 30 Voltage Rails

Mark Fortunato
amrutah
amrutah
3/1/2013 9:15:08 AM
User Rank
Master
Re: The battery pack is 3.7V???
Mark,

   My mistake, I completely misread it.

I have worked on PM chips which has somewhere around 10-11 LDO's, 3-4 switchers for supply rails and around 8-10 grounds (reference ground planes), which in itself is very complex considering: handling amps of current, the chip temperatures (hot regions), the associated clocking scheme, digital for powerup sequencing and so on...

  Integrating 30+ voltage rails is a stupendous jobs which will invite a lot of accolades!!!

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Mark Fortunato
Mark Fortunato
2/21/2013 12:02:17 PM
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Newbie
Re: The battery pack is 3.7V???
Amrutah,  I think you misread the title.  I was not talking about a 30 volt rail (a supply of 30 volts).  I was talking about the phone having 30+ rails requiring 30+ regulators.

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amrutah
amrutah
2/21/2013 5:47:47 AM
User Rank
Master
The battery pack is 3.7V???
Mark,

   The battery pack is usually 3.7V, atleast the one that I have (Google Nexus One).  I dont understand the place where we need 30V so that we boost the 3.7V volts to 30V.  The micro SD card, SIM card, GPS and WiFi work at near to 5V.

I thought that there might be places like the EEPROM inside a chip that might need some high voltage (a charge-pump like module might be suffcient to raise a momentary high voltage).  

I really dont understand where the Voltage rails are 30V inside my smartphone?

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RedDerek
RedDerek
2/20/2013 11:22:39 AM
User Rank
Master
Re: Tell Me Why My Smartphone Requires 30 Voltage Rails
Multiple rails are for different systems. When I was marketing manager and working with digital camera folks, look at the supply count: + and - for the LCD, plus a bias for contrast, uP gets a supply, on-board memory another, flash memory insert gets another, two more for the CCD, and so-forth. Early products start with assembling different technologies into one device. As technology improves, newer voltage supplied products come out so that similar voltages can be used and thus reduce power rail count.

And, as said earlier... power supplies are more of an after-thought. Making power supply design fit the left-over space is the joys of designing.

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SunitaT0
SunitaT0
2/20/2013 4:01:11 AM
User Rank
Master
Tell Me Why My Smartphone Requires 30 Voltage Rails
Mark,

Multiple voltage rails are required to drive a variety of device loads spread across the IC. The digital electronic components and circuits such as motherboard, adapter cards, and disk drive logic boards typically use the power supply of 3.3V or 5V whereas motors like disk drive motors, high-output voltage regulators use the 12V power.

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Mark Fortunato
Mark Fortunato
2/19/2013 5:37:39 PM
User Rank
Newbie
Re: Because Power Managment gets no respect!
Doug, yes, I remember those days well.  5V and +/-15 was all we needed.  But then didn't we have to hand-crack our cars to get them started back then?

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Doug Grant
Doug Grant
2/19/2013 5:23:36 PM
User Rank
Blogger
Because Power Managment gets no respect!
The problem is that the digital stuff drives everything else. Powr is always an afterhought..."oh, we'll just add another regulator if we need one - they're cheap and small, either integrated or discrete". Those 30 rails probably include 10 different voltages for the various processor cores, each separately enabled to save power when that particular core isn't needed. Then separate rails for the I/O drivers and memories. Then additional rails for the mixed-signal and RF sections, each with a different voltage and a low-noise LDO fo rthe VCOs. Ah...for the good old days of a single digital rail...and one or two for the analog stuff.

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