LMR43610: input current at light loads

Alex Palii

Part Number: LMR43610

Hello, TI team! A step-down stabilizer is needed: Input voltage 3.3 V - 7 V. Output voltage 3.3 V. What is the input current of the LMR43610 at a load current of 5 - 10 µA? Thank you!

11 months ago

0 Joshua Austria 11 months ago

TI__Genius 12615 points

Hi Alex,

Thank you for your question. For your conditions you will have these approximate values for your input current:

VOUT = 3.3 V, VIN = 3.3 V, IOUT = 5 uA: IIN = 12 uA

VOUT = 3.3 V, VIN = 7 V, IOUT = 5 uA: IIN = 6.6 uA

VOUT = 3.3 V, VIN = 3.3 V, IOUT = 10 uA: IIN = 18 uA

VOUT = 3.3 V, VIN = 7 V, IOUT = 10 uA: IIN = 9.56 uA

Thank you,

Joshua Austria

0 Alex Palii 11 months ago in reply to Joshua Austria

Prodigy 45 points

Hi Joshua,

In what mode does the LMR43610 provide this data, PFM or FPWM?

Best regards, Alex.

0 Joshua Austria 11 months ago in reply to Alex Palii

TI__Genius 12615 points

Hi Alex,

It should be PFM. Although I would imagine at such a light load FPWM may be fairly similar to these theoretical values as well.

Thank you,

Joshua Austria

0 Alex Palii 11 months ago in reply to Joshua Austria

Prodigy 45 points

Hi Joshua,

Are the given values practically measured on the EVM or theoretical?

Best regards, Alex.

0 Joshua Austria 11 months ago in reply to Alex Palii

TI__Genius 12615 points

Hi Alex,

This data is theoretical.

Thank you,

Joshua Austria

0 Alex Palii 11 months ago in reply to Joshua Austria

Prodigy 45 points

Hi Joshua,

Please measure the input currents on the LMR43610 EVM, if possible. Input voltage 3.3 V, 4.5 V, 5.2 V, 6.6 V. Output voltage 3.3 V. What is the input current of the LMR43610 at a load current of 5 - 10 µA.

Best regards, Alex.

0 Joshua Austria 11 months ago in reply to Alex Palii

TI__Genius 12615 points

Hi Alex,

Unfortunately, this will take some time for me to get this data. I will say however, that this theoretical data should be very close to the actual values if there are any differences at all.

If you would still like me to measure this please let me know and I will get back to you as soon as possible.

Thank you,

Joshua Austria

0 Alex Palii 11 months ago in reply to Joshua Austria

Prodigy 45 points

Hi Joshua,

I would like to obtain experimental data in two modes: PFM and FPWM.

And another question - if the input voltage is close to the output voltage, how will the upper and lower switches function?

Thank you!

Best regards, Alex.

0 Joshua Austria 11 months ago in reply to Alex Palii

TI__Genius 12615 points

Hi Alex,

I will have to get this data to you sometime later. I will update you once I get it.

In regards to your other question, what information do you want about how the upper and lower switches function? Some special cases are detailed in sections 8.4.3.4 and 8.4.3.5 of the datasheet but otherwise the switches will operate in a peak current mode control structure. You can find more information here if you would like: Current Mode Control Theory.

Thank you,

Joshua Austria

0 Joshua Austria 11 months ago in reply to Joshua Austria

TI__Genius 12615 points

Hi Alex,

Here is the data I got:

PFM

3.3 V: 3 mA (the part is in dropout)

4.5 V: 17 uA

5.2 V: 15 uA

6.6 V: 13 uA

FPWM

3.3 V: 3.16 mA (the part is in dropout)

4.5 V: 8.11 mA

5.2 V: 7.8 mA

6.6 V: 7.4 mA

Thank you,
Joshua Austria

0 Alex Palii 11 months ago in reply to Joshua Austria

Prodigy 45 points

Hi Joshua,

1.At what load current were these values obtained? 2. Why is there such a large current ( 3 mA) at an input voltage of 3.3 V in PFM mode?

Thank you!

Best regards, Alex.

0 Joshua Austria 11 months ago in reply to Alex Palii

TI__Genius 12615 points

Hi Alex,

Around 7 uA load.

The device is in dropout and cannot properly regulate to 3.3 Vout with only 3.3 Vin. As a result the frequency of the device's operation drops and the device is unable to maintain its low input current as the inductor takes longer to reach its desired peak than normal. See section 8.4.3.5 in the datasheet for more information.

Thank you,

Joshua Austria

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LMR43610: input current at light loads