LPC MicrocontrollersのトピックRe: LPC55xx: Specifications internal reference voltage

LPC55xx: Specifications internal reference voltage

janpieterderuit — Sat, 18 Jul 2020 09:26:15 GMT

Hi,

from table 706 in the user manual (UM11126) I get that the ADC can measure a 1V reference voltage ("Bias_vref_1v from aux_bias module").

I would like to use it, but I can't find any specification for it in the datasheet (e.g. voltage tolerance and temperature dependency).

Wher can I find those specs?

Also from the SDK I get that bit 1 of the PDRUNCFG0 is used to disable/enable power to this bias voltage, however in table 291 of the user manual this bit is said to be reserved, and bit 19 should be used.

The SDK says that bit 19 is for LDOGPADC...

SDK says bit 15 is for GPADC, the user manual says this bit is also reserved.

All in all I'm a bit puzzled which bits I should use to get the ADC and reference voltage working.

Can someone explain how to use the reference voltage?

Thanks in advance.

Re: LPC55xx: Specifications internal reference voltage

xiangjun_rong — Mon, 20 Jul 2020 04:51:37 GMT

Hi, Jan,

what the Um said is vague, I have asked the AE team, I will answer you after I get a feedback.

Xiangjun Rong

Re: LPC55xx: Specifications internal reference voltage

janpieterderuit — Thu, 06 Aug 2020 04:13:33 GMT

Hi Xiangjun,

Do you have any update on this?

Thanks

Re: LPC55xx: Specifications internal reference voltage

ZhangJennie — Mon, 10 Aug 2020 03:37:21 GMT

Jan,

BIAS_VREF_1V is 1.5% accuracy over working voltage and temperature range.

Jun Zhang

Re: LPC55xx: Specifications internal reference voltage

xiangjun_rong — Thu, 13 Aug 2020 06:32:28 GMT

Hi, Jan,

The bit 19 in PDRUNCFG0 for LPC55S69 can control the BIAS_VREF_1V. For accuracy of testing the 1V voltage reference, user have to choose the two options for the ADC converter:

g_LpadcCommandConfigStruct.sampleTimeMode = kLPADC_SampleTimeADCK131;
g_LpadcCommandConfigStruct.hardwareAverageMode = kLPADC_HardwareAverageCount128;

As my colleague Jennie said that the voltage reference can reach up to 1.5% accuracy with above options

over working voltage and temperature range.

Hope it can help

XiangJun Rong

Re: LPC55xx: Specifications internal reference voltage

janpieterderuit — Mon, 17 Aug 2020 13:24:25 GMT

Hi Jennie, XiangJun,

thanks for your response.

Will the datasheet/User Manual be updated with this info?

Jan Pieter

Re: LPC55xx: Specifications internal reference voltage

xiangjun_rong — Tue, 18 Aug 2020 07:15:49 GMT

Hi, Jan,

I have notified the AE team of updating the BIAS_VREF_1V part in the UM for LPC55xx family.

Xiangjun Rong

Re: LPC55xx: Specifications internal reference voltage

janpieterderuit — Tue, 18 Aug 2020 20:14:20 GMT

OK, thanks

Re: LPC55xx: Specifications internal reference voltage

mse_videotec — Fri, 26 Nov 2021 16:18:42 GMT

Hi!

Is it exactly 1.0V?

Many thanks

Mirco