The LM62440-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 VOUT /
VIN.
Equation 3. ![GUID-E3084FF6-C910-4217-835B-4E2428AA6740-low.gif](/ods/images/JAJSIW6E/GUID-E3084FF6-C910-4217-835B-4E2428AA6740-low.gif)
where
- IQ_VIN is the current consumed by the operating (switching) buck converter while unloaded.
- IQ is the current drawn from the
VIN terminal. See IQ in Section 8.5.
- IEN is current drawn by the EN
terminal. Include this current if EN is connected to VIN. See IEN in Section 8.5. Note that this current
drops to a very low value if connected to a voltage less than 5 V.
- Idiv is the current drawn by the feedback voltage divider used to set output voltage.
- ηeff is the light-load efficiency of the buck converter with IQ_VIN removed from the input current of the buck converter. ηeff = 0.8 is a conservative value that can be used under normal operating conditions.