SK-AM62A-LP: Why are two 32.768KHz crystals required for AM62A MCU and PMIC

Wells Zhu

Part Number: SK-AM62A-LP

Tool/software:

Dear TI experts,

On the schematics of SK-AM62A-LP, a 32.768KHz crystal(Y3) is connected to PMIC TPS65931211RWER, and a 32.768KHz crystal(Y2) is connected to AM62Ax MCU. For a conventional design, only a 32.768KHz crystal is required to MCU or PMIC. Then the RTC clock can be shared between MCU and PMIC. Why are two 32.768KHz crystals required for AM62Ax platform? Please help explain the reason.

Best regards,

Wells

4 months ago

0 Swargam Anil 4 months ago

TI__Mastermind 46976 points

Hello Wells,

I am routing your query to Hw expert .

Regards,

Anil.

0 Kallikuppa Sreenivasa 4 months ago in reply to Swargam Anil

TI__Guru**** 192939 points

Hello Welles,

PMIC use case

www.ti.com/.../tps6593-q1.pdf

9.2.1.2.3 Crystal Oscillator A crystal oscillator can be used for application requiring a high accuracy real-time clock module. The OSC32KCAP pin is bypassed with a 100-nF bypass capacitor for noise rejection. For the OSC32KIN and OSC32KOUT pins, a simplified oscillator schematic is shown in Figure 9-2 to determine what external load capacitors are needed for the crystal.

WKUP_LFOSC0_XI, WKUP_LFOSC0_XO

WKUP oscillator has limited use case including clocking internal RTC module accurately.

We have been recommending customer to provide provision to ground Xi when not used.

Refer SOC data sheet for more information.

(+) [FAQ] AM62A7 / AM62A7-Q1 Custom board hardware design – Collaterals to Get started - Processors forum - Processors - TI E2E support forums

Regards,

Sreenivasa

0 Wells Zhu 3 months ago in reply to Kallikuppa Sreenivasa

Prodigy 90 points

Hello Sreenivasa,

Thank you for your reply.

If PMIC oscillator is used and WKUP oscillator is not used, is there any disadvantage that any function can't be realized?

Regards,

Wells

+1 Kallikuppa Sreenivasa 3 months ago in reply to Wells Zhu

TI__Guru**** 192939 points

Hello Wells,

Thank you.

The WKUP_LFOSC0 has limited use case (used as accurate RTC clock ).

There are connection requirements for the WKUP_LFOSC0 described in the data sheet that needs to be followed.

There is no WKUP_LFOSC0 clock and PMIC clock dependencies.

Regards,

Sreenivasa