Table 1 on page two show two IRF components: ILRML2502, ILRML6401
However, I could only find IRLML2502 and IRLML6401.
If I read the datasheets right, they show:
the RDs for IRLML2502 as 80 mOhms at 2.5V not 2.7V
and for IRLML6401 as 85 mOhms at -2.5V not 2.7V.
Jon