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TINA/Spice/LP3985: TINA model for LP3985 2.5V

Part Number: LP3985
Other Parts Discussed in Thread: TINA-TI, , TLV713, MSP430F2101, LP3983, TPS62125, LP2985, MULTIPKGLDOEVM-823, DEM-SOT23LDO

Tool/software: TINA-TI or Spice Models


in order to compare startup behavior of LP3985 (2.5V) to TLV713 (2.5V) I am looking for SPICE macros (even encrypted) for both devices to use TINA-TI simulator.

My circuit is powered by a 16.5V battery pack. A buck converter TPS62125 converts 16.5V down to 5V for maximum load current of 100mA. This is also used as the Vin for an LDO, to be chosen between LP3985 or TLV713, to power an MSP430F2101 at 2.5V. Till present I used macros of LP3983 and TLV71310 that seem the only one available similar to LP3985 and TLV71325 but I need to characterize startup time of 2.5V with good reliability in oreder to choose the LDO.

Many thanks


  • Hi Mauro,

    FYI, We're evaluating your inquiry.

  • Hi Mauro,

    We do not have a model for LP2985 available and have no plans of releasing one for this older device.  Both the LP2985 and TLV713 datasheets contain startup curves.

    TLV713 is only offered in fixed output versions and does not have an NR pin.  As such, the Vout startup slew rate is only limited by the Vin slew rate (if EN is tied to IN) or current limit due to the need to charge large output capacitors.

    LP2985 has a BYPASS pin which serves the same function as an NR pin.  Cbypass is connected to the internal reference voltage.  During startup Cbypass is charged with an internal 70 uA current source until the internal reference voltage reaches its final value of 1.23 V.  As such, you an calculate the turnon time for this device based on the Cbypass used:

    We recommend prototyping in order to better understand how a linear regulator will perform under your specific application conditions.  MULTIPKGLDOEVM-823 or DEM-SOT23LDO can be used to speed up your prototype process.

    Very Respectfully,


  • Thank you, Ryan. My main concern is to find possible instability related to TPS62125 buck converter powering the LDO.

    TPS62125 is enabled by a Reed switch, usually affected by contact bouncing.

    Output from TPS62125 (5V) powers up the LDO (either LP3985 or TLV713).

    Output from LDO (2.5V) powers up the MCU (MSP430F2101).

    Startup time of LDO (from initial Reed switch enable) shall be <300us (i.e. negligible with respect to MCU startup time of about 2ms).

    To cope with possible instability PG from TPS62125 could be used to drive LDO enable but this will increase startup time up to 600us or more.

    That is why I would really prefer to simulate for possible instability and choose the LDO with shortest startup time.

    For further clarifications I attach the two schematics I used to simulate with LP3983 and TLV71310 as the best matching I found for LP3985 and TLV71325.




  • Hi Mauro,

    If you are looking for the fastest startup time between these two devices, LP3985 will be the fastest startup time.

    The TLV713 has a nominal startup time of 100 us.

    LP3985 has a nominal startup time of 200 us with a Cbypass of 0.01 uF.

    While TLV713 does not provide a method for the user to adjust the startup time, LP3985 does with the Cbypass.  If you were to remove the Cbypass, you will achieve a faster startup time (~40 us) as shown in the Typical Performance Characteristics curves:

    Very Respectfully,


  • Hi Ryan,

    Thank you for the support. I agree that LP3985 with no bypass capacitor is the best solution for fastest startup, in spite of an increased whilst acceptable output noise.

    Best regards,