ADJ Pin Voltage

Hello Koji,

Both values are correct.

You correctly understand that AVL2 and AVCC2 are adjustment pins for the internal LDO's supplying the associated outputs.  In particular, this means that they are the feedback inputs for the LDO's error amplifier.  The LDO's error amplifier's reference level is 0.6V.  Using standard design practice, the feedback network gain (voltage divider ratio) is set to produce a 0.6V feedback input to the amplifier when the output is at the desired voltage (zero error).  Hence the design equations on page 17 use 0.6V.

The values in the electrical characteristics table on page 4 provide a measured range of possible values for this voltage over different loading and operating conditions and part variations. The typical value of 0.58V reflects the LDO's output voltage droop from a loading current of 100mA.  Note that this feedback voltage would correspond to an output voltage of approximately 4.83V which is within the LDO's 5% output regulation specification listed in the LTM2887's data sheet (4.75-5.25V).

Eric

Hi Eric,
Thank you for quick response.

I thought that the output voltage was 5V even when ADJ=0.58V.
I now understand that when it is 0.58V, the output voltage is approximately 4.83V.

Best Regards,
Koji