LM5106: EN pin toggling

Hi Radar,

I am an applications engineer for this device.

My first impressions are yes, the LM5106 can support a rapidly toggling signal unrelated to the input signal but let me verify this behavior on the bench.

Are you concerned that the operation of the enable pin will fail with an oscillating signal at EN?

Regards,
Mateo 

Mateo,

Thanks for the bench verification offer; I think that's what's needed; becuase like you, my initial thoughts were, sure, should work... but...the concern would be this- level shifts are most often implemented with some sort of hysteresis or thresh-hold detect; so if say the PWM input goes high and the high side FET turns on; then infinitesimally later tries to disable the output; does the detect have some lag before the output truly turns off (or more horridly; it’s hopefully not an edge detect and it stays on waiting for a disabled edge that’s now never going to come in).  We’re really mostly concerned that the EN will behave as a real enable- that is, low means output off in all cases.  And I would add; we’d want to know about the low side control too- it’s just for the low side I suspect it’s a ‘real’ gate and thus just works normally; whereas the level shift piece on that high side one is post-gate; and thus introduces the opportunity for squirreliness

Radar,

I have received some samples of the LM5106 and will update you when I take some measurements on the bench.

regards,
Mateo

Hi radar,

I am working on getting this back to you today!

Regards,
Mateo

Hi Radar,

I was able to capture the following waveforms on the bench: [ Channel 1 (yellow): IN, Channel 2 (cyan): EN, and Channel 3 (magenta): LO ]

I used 100kOhm for R_DT which

test conditions:

IN: 20kHz, 50% duty cycle pulse

EN: 19kHz, 50% duty cycle pulse

I was able to confirm values from figure 1 in the datasheet despite IN and EN being out of sync.

regards,
Mateo