LM1117: LM1117 with lower Vin will affect life time or not

Kuan Wei Chen (Kevin Chen)

Genius 9710 points

Part Number: LM1117

Dear Team,

Can we discuss more for below thread?

http://e2e.ti.com/support/power-management/f/196/p/839255/3104241#3104241

I understand LM1117 output will not be 5V under such operation condition.

Therefore, I want to know how to calculate the actual output voltage and whether this operation (5.5Vin, Load 100mA) will affect the lifetime of LM1117 or not.

In normal operation, the input of LM1117 will be 6.5V and load 100mA in our product.

However, in some circumstances, the input of LM1117 might be 5.5V and the load will be light. But it doesn’t need to confirm the accuracy of 5V port.

This circumstance only need to confirm stable 3.3V for DSP working. (This 3.3V will be provided from another regulator IC which minimum operation input voltage is 4.5V)

Please help to check this operation will affect the LM1117 lifetime or not. Thanks.

Kevin

over 6 years ago

0 Kyle Van Renterghem over 6 years ago

TI__Genius 14245 points

Hey Kevin,

For 100mA the dropout in the EC table shows that it will be between 1.1V-1.2V so if Vin=5.5V and Iout=100mA then the output voltage will be between 4.4V-4.3V. If the load is going to change, you can use the dropout vs load current graph to estimate how much the output will be reduced.

As for the reliability question of running the LDO with lower Vin, no using a lower Vin will not decrease the lifetime reliability.