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How is the low voltage detector LBD used in the phone MCU?

April 26, 2017Detector LBD low mcu phone Used voltage

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How is the low voltage detector LBD used in the phone MCU?

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• The LBIN Pin in the phone MCU is used to detect an external voltage lower than 1.15V. • It is recommended that a precision resistor voltage divider is used as shown in the diagram. To detect the external VDET voltage, the formula is 1.15 = VDET x (R2/(R1+R2)). For example, if it is desired to detect an external voltage VDET=2.4V, by using the formula a value of R2=0.92R1 is achieved. If R1 is chosen to be 2.2Mohm, then R2=2.0Mohm. • During the design process it is only required to set LBEN to 1 and check the LBFG using software instructions. If LBFG=1, the voltage of the LBIN Pin will be less than 1.15V. If LBFG=0, the voltage of the LBIN Pin will be larger than 1.15V.