MM912J637 - Operation at 3.3Volts

[igw]

Hello all,

The MM912J637 (and MM912I637) data sheet states that operating conditions for VDDRX can range from 3.13 to 5.5 volts.  This seems clear enough.

Can I run the device from an external 3.3V regulator rather than looping VDDX to VDDRX?

Will there be a problem due to the Clamp5V supply during STOP mode?

The data sheets says for the VDDRX pin "This pin must be connected to VDDX.".  This suggests I can't do what I want to do. Also the low voltage interrupt and reset conditions mentioned in Section 3.5.2 (table 24) suggest it is pretty marginal.  So which data is correct.

(I was going to use the VDDX output to shutoff the external 3.3V regulator during sleep/stop modes.)

A couple of related things:

Section 3.3 Operating Conditions of the data sheet mentions that the range of operation for VDDRX is 3.13 to 5.5V.  Yet the 5V regulator output, VDDX, can range from 3.15 to 5.9V.  So the VDDX can possibly generate a voltage beyond the stated operating limits of the VDDRX input.  The data sheet says these can (maybe even normally are) connected together.  So why is the regulator output able to generate a voltage beyond the operating conditions?

The stated output voltage range of the VDDX regulator is enormous - 3.13 to 5.9V.  Why so large?

Thanks,

Ian

[iggi]

Hello Ian,

It will be possible to set VDDRX through an external regulator. The drawback is that you will have to handle the power supply and synchronization constraint by your own.

The power management scheme (while connecting VDDX to VDDRX, and VDDH to VDDD2D, and RESET to RESETA) is insuring that at power up/down and after wake-up and entering into low power mode the device supplies are well set. This will require to be handled by the system of the user.

Also you need to take into account the Absolute Maximum Ratings and Operating Conditions of VDDRX as described in the datasheet.

Regards,

iggi