DC1237A-A for LTC3527 evaluation

ogura.isao@sankyosha.co.jp

Can you take the waveforms of VIN (2.4V) as well? Also can you increse 2.4V curerent limit, to make sure it does not interfer with your test? 

/SHDN2 is connected to VIN, so it only change a little.

here is another oscilloscope waveform.

- JP7(VOUT1) to 5V and connect 50ohm load.
- JP8(VOUT2) to 3.3V and connect the electronic load(10mA)

-JP3 tp auto burst mode
- JP4 to 1.2MHz
- JP5(/SHDN1) to EXT
- JP6(/SHDN2) to ON
- JP1 to Parallel and connect Power Source with the setting og 2.4V and current limit 2A

when VOUT1 ramps up, SW2 stops a little while. and SW2 changes from burst mode to fix mode.

Does SW2 stops when VOUT1 ramps up?

but during vout1 ramps up, SW2 is NOT burst mode nor fixed mode. is this right operation?

/SHDN2 is connected to VIN, so it only change a little.

here is another oscilloscope waveform.

- JP7(VOUT1) to 5V and connect 50ohm load.
- JP8(VOUT2) to 3.3V and connect the electronic load(10mA)

-JP3 tp auto burst mode
- JP4 to 1.2MHz
- JP5(/SHDN1) to EXT
- JP6(/SHDN2) to ON
- JP1 to Parallel and connect Power Source with the setting og 2.4V and current limit 2A

when VOUT1 ramps up, SW2 stops a little while. and SW2 changes from burst mode to fix mode.

Does SW2 stops when VOUT1 ramps up?

but during vout1 ramps up, SW2 is NOT burst mode nor fixed mode. is this right operation?

I did the test further and found that SW2 behavior during VOUT1 ramps up has LOT dependency.

I tested ICs with LOT number <330,<744,<851. IC with <851 is mounted on the evaluation board and

whose waveform I posted above.

<330 does NOT have SW2 stop behavior, but <744 and <851 have SW2 stop behavior.

I just like to konw what is the cause of SW2 stop and why it has LOT dependency.

Please contact local ADI FAE or sales. I will do it in parallel too so someone can reach out to you.

Can you test the circuit again with JP3 set to fixed frequency?

I attached two files. red indicates vout1, green indicates SW2, blue indicates SW1

auto burst setting

fixed frequency

I'm working with our local FAE for this issue. Please contact them.