AM4378: Maximum power consumption in RTC-only mode

Hiroyasu Tazawa1

Part Number: AM4378
Other Parts Discussed in Thread: TPS65218

Hi,

Let me talk about Power Consumption of RTC only mode for AM437x.

My customer need to know about Maximum Power Consumption of RTC only mode.
Because They need to estimate life time of battery.

But We can not get this information from AM437x Datasheet.
Because Datasheet provide Power Consumption when AM437x is Active mode.
We need to know Maximum Power Consumption of RTC only mode

This Wiki page mention that RTC-only mode is < 30uW.

processors.wiki.ti.com/.../Processor_SDK_Linux_Kernel_Performance_Guide

I think we can estimate life time of battery.
My understanding is correct ??

My customer use Processor SDK Linux for AM437x.

Best Regards
Hiroyasu

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Hi,

The wiki page you refer provides actual data measured on the AM437x GP EVM. Table 5-4 in the AM437x Datasheet Rev. D gives the maximum current rating for the RTC domain, which is what you ask for.

0 Hiroyasu Tazawa1 over 6 years ago in reply to Biser Gatchev-XID

Guru 12350 points

Hi, Biser

Thank you for your reply.

No, I need to know RTC only mode.
CAP_VDD_RTC and VDDS_RTC on Table 5-4 Datasheet mentions that
maximum possible current consumption. CAP_VDD_RTC is 2mA and VDDS_RTC is 5mA.
It is too high.It means TPS65218 can handle the maximums when main power is active.

e2e.ti.com/.../625486

I need to know Power consumption in RTC only mode.

Best Regards
Hiroyasu

0 Biser Gatchev-XID over 6 years ago in reply to Hiroyasu Tazawa1

TI__Guru**** 393215 points

Please refer to the wiki page you mentioned.

0 kshin over 6 years ago

TI__Genius 16690 points

The parameters are not defined in the datasheet as the device is not screened for power in the RTC-only mode during manufacturing. On bench power characterization, this was the RTC-only power at different temp and device process variation. The power was measured at AM437x power supply input at VDDS_RTC and CAP_VDD_RTC. When coin cell battery lifetime is estimated, power loss by TPS65218 needs to be considered based on the power efficiency parameters in the TPS65218 datasheet.
RTC-only power
Typical: 8.6 uW at 25 C, 21.4 uW at 60 C
Max: 10.9 uW at 25 C, 25 uW at 90 C

0 Hiroyasu Tazawa1 over 6 years ago in reply to kshin

Guru 12350 points

Hi, kshin

Thank you for your reply.
I got it.

Best Regards
Hiroyasu

0 Hiroyasu Tazawa1 over 6 years ago

Guru 12350 points

Part Number: AM4378

Hi,

Let me talk about RTC only mode for AM437x.

I got Power Consumption value like this from this thread.

e2e.ti.com/.../632226

Max: 10.9 uW at 25 C, 25 uW at 90 C

I understand this cnsumption using VDDS_RTC＝1.8V only.
Because Power mode of RTC-only is described in Table 6-13 of TRM.

This understanding is correct??

Best Regards
Hiroyasu

0 Hiroyasu Tazawa1 over 6 years ago in reply to Hiroyasu Tazawa1

Guru 12350 points

Hi,

I'm sorry. It had my misstake.
I made new thread about this new question.

Thank you.

Best regards
Hiroyasu

0 kshin over 6 years ago in reply to Hiroyasu Tazawa1

TI__Genius 16690 points

The RTC-only configuration in the table 6-13 is when internal RTC LDO is enabled for 1.0 V core voltage. The bench measurement was done in the configuration described in Figure 2 in the TPS65218 user guide (www.ti.com/.../slvuaa9a.pdf). Both VDD_RTC and CAP_VDD_RTC are sourced by TPS65218. Those power numbers include power consumption on both VDD_RTC and CAP_VDD_RTC rails. Please note that the bench power numbers with limited samples are reference only and not screened or guaranteed for production devices.

0 Hiroyasu Tazawa1 over 6 years ago in reply to kshin

Guru 12350 points

Hi, Kshin

Thank you for your reply.

I understand you gave me these parameter does not include TPS65218 power loss.

Typical: 8.6 uW at 25 C, 21.4 uW at 60 C
Max: 10.9 uW at 25 C, 25 uW at 90 C

This understanding is correct ??

If It does not include, We need to know current of VDDS_RTC and CAP_VDD_RTC
for system power loss estimation.

Can you tell me Max current of VDD_RTC and CAP_VDD_RTC on RTC mode ?

Best Regards
Hiroyasu

0 kshin over 6 years ago in reply to Hiroyasu Tazawa1

TI__Genius 16690 points

Yes, that's correct.
Here is the power breakdown between 1.8V VDD_RTC and 1.0V CAP_VDD_RTC.
Again, this is not the spec value but bench measurement data based on limited samples.
Max:
10.9 uW (3.1uW@1V, 7.8uW@1.8V) at 25 C
25 uW (16.4uW@1V, 8.6uW@1.8V) at 90 C

0 Hiroyasu Tazawa1 over 6 years ago in reply to kshin

Guru 12350 points

Hi, kshin

Thank you !
I got it.

Best Regards
Hiroyasu

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AM4378: Maximum power consumption in RTC-only mode