Maximum clock frequency For MPU PLL

Keldy

Hi,

I'm using AM335x with VDD_MPU = 1.1V and VDD_CORE = 1.1V, with this setting, the datasheet mention that the ARM frequency is 500Mhz.

But from TRM (8.1.1.6.8.1 Configuring the MPU PLL), there is a way to configure the MPU PLL by changing the multipier and divider in CM_CLKSEL_DPLL_MPU register.

What is the Maximum clock frequency i can configure for MPU ?

Thanks and Regards

Keldy

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Keldy,

VDD_MPU and VDD_CORE voltages do not configure the frequency, the MPU PLL does. In your case (VDD_MPU = 1.1V and VDD_CORE = 1.1V) MPU PLL should be configured for ARM frequency of 500Mhz. These are called operating performance points (OPP) - AM335X datasheet tables 3-5 and 3-6 list the supported OPP's.

The maximum MPU clock frequency depends on the frequency rating of the processor you have. See page 215 of the AM335X datasheet for speed grades.

Best Regards

Biser

0 Peng Liu50174 over 12 years ago in reply to Biser Gatchev-XID

Expert 1510 points

Hi, Biser,

I'm using one D27 (275MHz) grade chip on one board (OPP 100 supply provided). I found the S/W has onfigured the MPU clock to 500MHz, but the board are working well w/o any issue at present. So I'm wondering what is the risk when configuing the MPU clock to higher frequency than speed grade listed in page 215 of the datasheet?

Thanks,

Peng

0 Biser Gatchev-XID over 12 years ago in reply to Peng Liu50174

TI__Guru**** 393215 points

All AM335X devices are initialized at 500MHz by ROM code. However 275MHz devices should be reconfigured to run at 275MHz (at OPP100 voltages) early in user software.

0 Peng Liu50174 over 12 years ago in reply to Biser Gatchev-XID

Expert 1510 points

Hi, Biser,

If I keep this overclocking, will the chip be damaged? Or just the power consumption will be increased?

0 Biser Gatchev-XID over 12 years ago in reply to Peng Liu50174

TI__Guru**** 393215 points

Processors should be used according to their specifications. Out of that it's your risk and responsibility.

0 Peng Liu50174 over 12 years ago in reply to Biser Gatchev-XID

Expert 1510 points

Hi, Biser,

Then using this D27 or 30 speed grade chips, can I change the VDD_MPU to turbo mode or Nitro mode level, then configure the MPU to work at 720MHz.

I didn't find introduction of Turbo mode and Nitro mode in the AM335X datasheet and TRM.

Peng

0 Biser Gatchev-XID over 12 years ago in reply to Peng Liu50174

TI__Guru**** 393215 points

Operating conditions are described in section 3.2 of the AM335X Datasheet, Rev.F:

275MHz devices can only operate up to OPP100 and 275MHz (Table 3-3 and Note 3 below the table).

300MHz devices can only operate up to OPP100 and 300MHz (Table 3-7 and Note 3 below the table).

0 Peng Liu50174 over 12 years ago in reply to Biser Gatchev-XID

Expert 1510 points

Hi, Biser,

I saw note 3 in the table 3-3. It tells OPP100 Applies to all orderable AM335_ZCZ_27 (275-MHz speed grade) devices. But it does not say 275MHz devices can only operate up to OPP100 and 275MHz.

And the the datasheet, doesn't see what speed grade chip can work under Turbo mode.

0 Biser Gatchev-XID over 12 years ago in reply to Peng Liu50174

TI__Guru**** 393215 points

Look at this table: http://www.ti.com/lsds/ti/arm/sitara_arm_cortex_a_processor/sitara_arm_cortex_a8/am335x_arm_cortex_a8/products.page

0 Peng Liu50174 over 12 years ago in reply to Biser Gatchev-XID

Expert 1510 points

Turbo OPP is for 80/100 speed grade chip, and Nitro OPP is for 100 speed grade chip. Right?

0 peaves over 12 years ago in reply to Biser Gatchev-XID

TI__Guru 63145 points

Figure 6-1 in the AM335x data sheet defines the device speed grade and valid OPP definitions can be found in Section 3.2.

Regards,
Paul

0 Biser Gatchev-XID over 12 years ago in reply to Peng Liu50174

TI__Guru**** 393215 points

Yes, this is correct.

0 peaves over 12 years ago in reply to Biser Gatchev-XID

TI__Guru 63145 points

Turbo for silicon revision 1.0 has a max operating frequency of 720 MHz and Turbo for silicon revision 2.x has a max operating frequency of 800 MHz . See Table 3-3 and Table 3-7 respectivly.

Nitro is only valid for Silicon revision 2.x and it has a max operating frequency of 1000 MHz. See Table 3-7.

Regards,
Paul

0 peaves over 12 years ago in reply to peaves

TI__Guru 63145 points

The maximum OPP supported by an AM335x device is defined by the speed grade marking on the top of the device.

For example, a device with speed grade of 27 will be a silicon revision 1.0 device that can be used in OPP100 and a device with speed grade of 30 will be a silicon revision 2.x device that can be used in OPP50 or OPP100.

Regards,
Paul

0 Peng Liu50174 over 12 years ago in reply to peaves

Expert 1510 points

I see. Biser and Paul, thanks.

Regards,

Peng

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Maximum clock frequency For MPU PLL