TPS62162: Vout accuracy of TPS62162

Yokota-san,

1. The line and load regulation accuracy specifications are given in the datasheet Electrical Characteristics Table in the OUTPUT section on page 6.  In your case, you are inquiring about low headroom drop out operation.  This is discussed in section 8.4.4 100% Duty Cycle Operation.  In that case:

Vout = Vin - Iout * (RDSon + Ldcr)

Where Ldcr is the output inductor DCR.

2. I do not have data for figure 19 at Vin <4V.

Yokota-san,

Vout accuracy is not applicable after duty cycle reaches 100%.  In that case the output voltage will be as high as possible.  You can calculate this drop out voltage for example, 3.3 V output with an inductor of 60 ohm DCR, the minimum input voltage for regulation at 1 A is:

3.3 + 1 * (0.430 + 0.060) = 3.79 V

So for Vin = 3.3 V, Vout = 2.81 V typical.

You may also want to factor in the worst case tolerance of the inductor DCR and high side FET RDSon.

Yokota,

It depends upon the inductor DCR and the output current.  For most cases, Vin > Vout + 1 is enough to be in less than 100% duty cycle.