topic Re: Not getting sine wave when TX-LDO is operating at 3V(external tvdd) in NFC

Not getting sine wave when TX-LDO is operating at 3V(external tvdd)

gokulkrishna — Mon, 09 Jul 2018 13:21:41 GMT

We are observing no change in wave-forms when the TXLDO_CONTROL_REG is changed. The TXLDO is configured as follows:

PH_REG_CLEAR_BIT(PMU_TXLDO_CONTROL_REG, TXLDO_ENABLE);
PH_REG_CLEAR_BIT(PMU_TXLDO_CONTROL_REG, TXLDO_LOW_POWER_EN);
PH_REG_CLEAR_BIT(PMU_TXLDO_CONTROL_REG,TXLDO_ENABLE_LP2);
PH_REG_SET_BIT(PMU_TXLDO_CONTROL_REG, TXLDO_LIMITER_EN);
PH_REG_SET_BIT(PMU_TXLDO_CONTROL_REG, TXLDO_OVERCURRENT_EN);
PH_REG_SET(PMU_INTERRUPT_SET_ENABLE_REG,PMU_INTERRUPT_SET_ENABLE_REG_TXLDO_OVERCURRENT_IRQ_SET_ENABLE_MASK);
PH_REG_SET_FIELD(PMU_TXLDO_CONTROL_REG, TXLDO_SELECT,E_TVDD_3M0_V);//3volt
PH_REG_SET_BIT(PMU_TXLDO_CONTROL_REG, TXLDO_ENABLE);

PH_REG_SET_FIELD(PMU_TXLDO_CONTROL_REG, TXLDO_SELECT_ANT,0x03);// TXLDO_DET_OUT range of 100mA

No NFC cards are able to detect with the current wave-form.

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Re: Not getting sine wave when TX-LDO is operating at 3V(external tvdd)

IvanRuiz — Fri, 13 Jul 2018 17:07:55 GMT

Hello,

Please let me get confirmation from internal team about your request. Will come back asap.

Regards,

Ivan.

Re: Not getting sine wave when TX-LDO is operating at 3V(external tvdd)

IvanRuiz — Fri, 03 Aug 2018 15:42:33 GMT

Hello,

Please see below answer from Apps team expert:

With the Settings on the TxLDO, you will not be able to Change the wave form. the TxLdo is only to deliver the Output power that is provided to the TVDD_Out pin, the shaping and wave-forms are set in different Registers. To Change or optimize you waveform see Antenna design guide AN11706 (Section 4.4 and following).

Regards,

Ivan.