9.2.2.9.1 Minimum Output Voltage
Due to the internal design of the TPS50301-HT, there is a minimum output voltage limit for any given input voltage. The output voltage can never be lower than the internal voltage reference of 0.8 V. Above 0.8 V, the output voltage may be limited by the minimum controllable on time. The minimum output voltage in this case is given by Equation 32.
Equation 32. V
OUTmin = Ontimemin × ƒsmax (V
INmax + I
OUTmin (R
DS2min - R
DS1min)) – I
OUTmin (R
L + R
DS2min)
where
- VOUTmin = Minimum achievable output voltage
- Ontimemin = Minimum controllable on-time (175 ns maximum)
- ƒsmax = Maximum switching frequency including tolerance
- VINmax = Maximum input voltage
- IOUTmin = Minimum load current
- RDS1min = Minimum high-side MOSFET on-resistance (36-32 mΩ typical)
- RDS2min = Minimum low-side MOSFET on-resistance (19 mΩ typical)
- RL = Series resistance of output inductor