The LM62435-Q1 is designed to have very low input supply current when regulating light loads. This is achieved by powering much of the internal circuitry from the output. The BIAS pin is the input to the LDO that powers the majority of the control circuits. By connecting the BIAS input pin to the output of the regulator, a small amount of current is drawn from the output. This current is reduced at the input by the ratio of V_OUT / V_IN.

Equation 3.

where

• I_{Q_VIN} is the current consumed by the operating (switching) buck converter while unloaded.
• I_Q is the current drawn from the V_IN terminal. See I_Q in Section 7.5.
• I_EN is current drawn by the EN terminal. Include this current if EN is connected to VIN. See I_EN in Section 7.5. Note that this current drops to a very low value if connected to a voltage less than 5 V.
• I_div is the current drawn by the feedback voltage divider used to set output voltage.
• η_eff is the light-load efficiency of the buck converter with I_{Q_VIN} removed from the input current of the buck converter. η_eff = 0.8 is a conservative value that can be used under normal operating conditions.