LDO Minimum Output

Vout_min = Vin − Vdrop

Quick answer

This calculator solves Vout_min = Vin − Vdrop for Min Output Voltage. With Input Voltage 26.4 V, Dropout Voltage 0.6 V, the result is 25.8 V. It solves in 3 directions, so you can enter the values you have and get the one you need.

Calculator

Min Output Voltage (V)
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Formula

Vout_min = Vin − Vdrop

Description

A low-dropout regulator (LDO) requires a minimum voltage difference between input and output to maintain regulation. The dropout voltage is the minimum Vin - Vout at which the regulator can still maintain its specified output voltage accuracy. Modern LDOs achieve dropout voltages as low as 30-200 mV at full load, compared to 1-2V for traditional linear regulators. Dropout voltage typically increases with load current. When Vin drops below Vout + Vdropout, the LDO enters dropout and the output follows the input minus a small saturation voltage.

Variables

  • Vout_min — Minimum regulated output voltage (V)
  • Vin — Input supply voltage (V)
  • Vdrop — Dropout voltage (V)

Practical Notes

LDO dropout voltage is specified at a particular load current and temperature. At light loads, dropout can be much lower. PMOS-based LDOs have lower dropout than NPN-based regulators. For battery-powered devices, low dropout is critical to extract maximum energy from the battery before the terminal voltage drops too low.

Symbols and units

Symbol Meaning Default unit Accepted units
Vout_min Min Output Voltage V pV, nV, µV, mV, V, kV
Vin Input Voltage V pV, nV, µV, mV, V, kV
Vdrop Dropout Voltage mV pV, nV, µV, mV, V, kV

Step by step

  1. 1. What you know: Input Voltage 26.4 V, Dropout Voltage 0.6 V
  2. 2. The relation: Vout_min = Vin − Vdrop
  3. 3. Substitute: Vin = 26.4 V, Vdrop = 0.6 V
  4. 4. Result: Min Output Voltage = 25.8 V

Worked examples

Minimum range

Given: Input Voltage 0.726 V, Dropout Voltage 10 mV

Result: Min Output Voltage = 0.716 V

Low range

Given: Input Voltage 7.26 V, Dropout Voltage 100 mV

Result: Min Output Voltage = 7.16 V

Typical

Given: Input Voltage 26.4 V, Dropout Voltage 0.6 V

Result: Min Output Voltage = 25.8 V

High range

Given: Input Voltage 0.506 kV, Dropout Voltage 0.9 V

Result: Min Output Voltage = 0.5051 kV

Maximum range

Given: Input Voltage 5.06 kV, Dropout Voltage 9 V

Result: Min Output Voltage = 5.051 kV

Solving for each variable

Solve for Min Output Voltage

Input Voltage 0.726 V, Dropout Voltage 10 mV → 0.716 V

Solve for Input Voltage

Min Output Voltage 0.33 V, Dropout Voltage 10 mV → 0.34 V

Solve for Dropout Voltage

Min Output Voltage 0.33 V, Input Voltage 0.726 V → 0.396 V

How Min Output Voltage changes with Input Voltage

Input Voltage (input) Min Output Voltage (result)
2.64 V 2.04 V
6.6 V 6 V
13.2 V 12.6 V
19.8 V 19.2 V
26.4 V 25.8 V
39.6 V 39 V
52.8 V 52.2 V
105.6 V 105 V
0.1848 kV 0.1842 kV
0.264 kV 0.2634 kV

The same result in other units

Unit Value
mV 25800
V 25.8
kV 0.0258

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Frequently asked questions

How do you calculate LDO Minimum Output?

Use Vout_min = Vin − Vdrop. With Input Voltage 26.4 V, Dropout Voltage 0.6 V, Min Output Voltage works out to 25.8 V.

What is the formula for LDO Minimum Output?

The formula is Vout_min = Vin − Vdrop. A low-dropout regulator (LDO) requires a minimum voltage difference between input and output to maintain regulation.

How do you find Input Voltage when you know the other values?

Rearrange for Input Voltage: with Min Output Voltage 0.33 V, Dropout Voltage 10 mV, Input Voltage is 0.34 V.

How do you find Dropout Voltage when you know the other values?

Rearrange for Dropout Voltage: with Min Output Voltage 0.33 V, Input Voltage 0.726 V, Dropout Voltage is 0.396 V.

What units does LDO Minimum Output use?

Min Output Voltage is shown in mV, V, kV. Values are held in SI base units internally, so you can mix prefixes without converting by hand.

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