L138 - dynamic voltage scaling

David Whitfield

Other Parts Discussed in Thread: OMAPL138

Hi,

Does the L138 require a power supply that implements a "dynamic voltage scaling" scheme in order to get up to the full 456MHz clock speed? I see a reference to it in the data sheet on pg 92 but it wasn't clear if that's a requirement thermally or just something that can be implemented to run at higher clock speeds and achieve lower power consumption.

Thanks

over 10 years ago

0 Titusrathinaraj Stalin over 10 years ago

TI__Guru** 116100 points

Hi David,

Does the L138 require a power supply that implements a "dynamic voltage scaling" scheme in order to get up to the full 456MHz clock speed?

What do you mean about power supply?

When you change CPU freq to 456MHZ at linux then voltage get changed accordingly(1.3V) by OPP definition.

Linux drivers ll take care the PLL settings to affect the CPU freq.

static const struct da850_opp da850_opp_456 = {
   .freq       = 456000,
   .prediv       = 1,
   .mult       = 19,
   .postdiv   = 1,
   .cvdd_min   = 1300000,
   .cvdd_max   = 1350000,
};

You can change the CPU frequency on the fly in OMAPL138 devices through "CPU Freq" linux driver support,

If ARM side(Linux)

http://processors.wiki.ti.com/index.php/OMAP-L1_Linux_Drivers_Usage#Power_Management

If DSP side,

http://processors.wiki.ti.com/index.php/Power_Module_for_C6748_and_OMAP-L138

Processors

Processors forum

L138 - dynamic voltage scaling