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LM26480-Q1: Is there a built-in delay for LDOs?

Part Number: LM26480-Q1
Other Parts Discussed in Thread: LM26480SQ-AAEV,


When using the LM26480SQ-AAEV evaluation board and also in the implementation of my design, I observe the following:

Using an input voltage of 3.3V and with the ENLDOx tied directly to VINLDOx, so that the LDOs are enabled as soon as the input voltage is applied, I observe a delay of approximately 6 ms from the voltage level at ENLDOx reaching 2V to when the output of the corresponding LDO ramps up.

I wonder if there is an undocumented delay in the startup of the LDOs. Section 7.6 of the datasheet mentions that the Turn-on time (Ton) for the LDOs is typically 300 us.

I will appreciate some guidance.

Kind Regards,


  • Hi Marco,

    I have forwarded your question to responsible applications engineer, but due to US Independence Day, his reply might delayed a little, thank you


  • Marco,

    Can you share the schematic of your LM26480-Q1 design?

    As the LM26480-Q1 datasheet says on page 15, I expect the SW1 and SW2 switching regulators to have a ~8ms delay during the first power on when ENSW1/2 is pulled up directly to VIN.

    "The enable signal may be employed immediately after VIN is applied to the device. However, VIN must be stable for approximately 8 ms before enable signal be asserted high to ensure internal bias, reference, and the flexible POR timing are stabilized. This initial delay is necessary only upon first time device power on."

    But I do not expect this delay to apply to the LDOs, as shown in Figure 28 and Figure 29 on page 30.