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TPS62125: TPS62125DSGR Output Voltage

Part Number: TPS62125


I am using TPS62125DSGR in my design which has 12 V at input voltage and 'Sensor_en' as the enable signal coming from FPGA. The ideal output at the output of TPS62125DSGR should be 2.82V. This 2.82 V is given to a LDO AP2202K-ADJTRG1 (Diodes Incorporated) which lowers it to 1.8V (VDD).

The problem I am having is when 'sensor_en' is high, then the voltage measured at LDO output comes out to be correct, i.e 1.8V, but when the 'sensor_en' is low then the voltage measured at the LDO output measures 1.4V, which ideally should be 0. Can you please look at the attached schematic page and tell how can that be possible,

Voltage Issue.pdf

  • Hi Sahil,

    1. What is voltage level for Sensor_en? Sensor_en voltage must be lower the Vin (12V).

    2. What is load condition on 1.8V rail? If it is no load or light load, the output voltage will decay very slowly. Please check waveform 2.82V and 1.8V during shutdown. Add a little bit load on 1.8V to see if it improves.

    3. Please review TPS62125  datasheet section 7.3.3/ output discharge through PG pin and Figure 55/56. You may use PG pin to make output discharge faster.

    Hope helps,