VRH pin and VDDX pin details

[pratimavishwaka]

Hi,

I came across two findings so want to discuss those points related to S12 MagniV microcontroller. The document, I referred is MC9S12ZVC-Family Reference Manual and Datasheet (MC9S12ZVC_RMV1)  .

First thing, as we know that there is one inbuilt ADC and has the supply of VDDA, VSSA. The reference voltage as specified in the Pin diagram is VRH but in the signal description of pins, the datasheet shows VRH_0 and VRH_1 as the two signals, details on Page No. 38 of 795. So, could you please provide clarification about the no. of VRH pins available for ADC in the S12ZVC microcontroller for ADC setting?  And can we externally provide VRH voltage?

Secondly, for the VDDX supply, Load current supplied by VDDX pin as in Page No. 725 of 795, shows same description Sr. No. 4 and 5, of Table E-1. The values are different but the description is same. So, could you please tell the maximum load current value supplied by VDDX without PNP transistor?

[RadekS]

Hi Pratima,

Please see chapter 1.9.3.1 ADC Reference Voltages

ADC reference Voltage signal VRH_1 is mapped to VDDA and VRH_0 is mapped to PAD3. VRL_1 is mapped to VSSA and VRL_0 is mapped to VSSA.

So, if you will configure ADC command for VRH_1/VRL_1 use, the ADC will take PAD3 pin voltage as the reference.

About VDDX parameters)

The descriptions are different in the temperature range.

So, internal VDDX regulator could provide 70mA only in the case when junction temperature is below 150°C. The lower limit (55mA) is valid for full range up to 175°C.

“Table E-1. Voltage Regulator Electrical Characteristics (Junction Temperature From –40°C To +175°C)”

I hope it helps you.

Have a great day,
Radek

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[pratimavishwaka]

Hi Radek,

Thanks for sharing the reply soon. The doubt for the VDDx is cleared.

But for VRH pin, the description that you had suggesed, I have already gone through that.

The concern is that, when I see the 64 pin IC, the pin no. 20 is VRH, which shows that there is only one VRH pin, not VRH_0 and VRH_1?

So, if I dont want to give external supply to pin no. 20 (VRH), I have to configure the VRH_SEL bit as 1 which will configure the VRH pin to VRH_1. Then, the ADC will use the VDDA supply as reference.

And if I want to give external supply to the pin 20 (VRH), the configuration for VRH_SEL bit will be 0 which will configure the same VRH pin to VRH_0. So, the ADC will use PAD3 voltage where the external supply is given.

Kindly correct me for the above statements. And provide your suggestion for the same.

[RadekS · Accepted solution]

Hi Pratima,

It seems that you just use some older version of RM. The latest version of RM (version 1.5) has signal VRH_0 at pin 20 of 64pin LQFP package.

In fact, the Revision History shows that this was already fixed in version 1.4.

Please download the latest version of RM:

http://www.nxp.com/files/microcontrollers/doc/ref_manual/MC9S12ZVCRMV1.pdf

Yes, you understanding about VRH_SEL bit is correct.

The PAD3 VRH reference might be used for example in the case when we want to use 4.192V voltage reference (The LSBs could be easily translated to mV, this reference might be more precise,…).

I hope it helps you.

Have a great day,
Radek

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[pratimavishwaka]

Thanks Radek for providing the details.

Best Regards

Pratima