TPS73101-EP: Reverse Leakage current and 4MHz Charge Pump noise level

Hi Sugumar,

See my answers to your questions below. 

1) In that condition sometimes, Output side revere voltage may be applied at +3.3V. In this LDO enable condition (EN , VIN +3.2V) what is the maximum reverse Leakage current? Note that, if Ven is not held low (<0.5V) then the reverse current protection/blocking is not activated so it would be good to ensure that the input voltage does not fall more than 300mV below the output voltage otherwise the LDO could be damaged by reverse current. But to answer your question, if Vout=3.3V with the output set to regulate at 3.15V then the LDO will turn off the pass device since the output is above the target voltage. With 100mV difference between Vin and Vout the leakage will be very small however I do not have an exact value for the current flowing from Vout to Vin but if your concern is the current on the 3.3V Vout supply then note that there is an 80k resistor divider to GND which will result in ~40uA of current flowing from Vout to GND. 

2) In your LDO charge pump using 4MHz used, What is the output noise level in LDO output for this 4MHz leakage from charge pump? I will need a couple of days to consult with a design engineer and look into this as I cannot find any noise data beyond 100kHz. 

3) Do you have better device for our above requirement. Below are some other -EP products you may be interested in assuming you require the LDO to be HiRel/Enhanced Products. Note the other two devices do not have reverse current protection when Ven is low. 

Hi Sugumar,

I wanted to follow up and let you know we are still working on getting the noise information you requested, unfortunately finding this data has been more difficult than expected. 

Hi,

We are more worried about reverse current during EN in ON condition when VIN<VOut condition. In which condition it will fail exactly, Can you elaborate?

Hi Sugumar,

When EN is ON the reverse current is not limited by the device and will follow the general I/V curve of a diode. In general we do not recommend that LDOs be exposed to reverse current which is more than 5% of their rated current (since this device is rated for 150mA that would be 7.5mA). That does not mean the LDO will fail catastrophically just above 7.5mA however there could be long-term reliability concerns or specification changed and you would need to verify that it continues to meet your application's requirements after such exposure. 

As a general guideline, to limit the amount of reverse current when an LDO does not have reverse current protection we recommend that Vin remains no lower than  300mV-400mV below the output voltage. This will limit the amount of reverse current by keeping the parasitic body diode from turning on. 

If you cannot avoid this situation in your application then we'd recommend adding a reverse current protection diode. Below is a link to more information on reverse current and two ways to implement the reverse current protection diode. 

LDO Basics: Preventing reverse current

In most low-dropout regulators (LDOs), current flow is like one-way street – go in the wrong direction and major problems can occur! Reverse current is current that flows from V OUT to V IN instead of…

By Mark Sellers over 7 years ago in Technical articles > Power management