The low dropout of dual supply TCR5AM series LDO (in the green lines) is shown on this slide. It can be seen that the line is close to being an ideal voltage regulator. The higher the VBAT is, the more ideally the LDO behaves. Compare this with a standard single-supply P-channel LDO, the TCR3DM. In particular, the lower the output voltage becomes, the bigger the dropout and wasted power is.