SG3524: Dead Time

Hello,

Is every device like this? Can you try a different device?

Can you try a big CT such as 3.3nF?

Sean-san,

Sorry for my reposes delayed.
The customer checked multiple devices and got the same result.  

Best Regards,
Akihisa Tamazaki

Sean-san,

I got the waveform as the following. The customer checked the waveform in 1nF and 10nF cases.

<1nF case  : dead time :1.7us>   CH1：EMIT1,  CH2：EMIT2
/resized-image/__size/1920x1080/__key/communityserver-discussions-components-files/196/CT_3D00_0.001uF_5F00_EMIT1_2D00_EMIT2_5F00_deadtime1.png

<10nF case : dead time 20us>   CH1：EMIT1,    CH2：EMIT2
/resized-image/__size/1920x1080/__key/communityserver-discussions-components-files/196/CT_3D00_0.01uF_5F00_EMIT1_2D00_EMIT2_5F00_deadtime2.png

I asked the customer to show the schematics around SG3524 and  and am waiting for it.
If you can advice after checking waveform, would you please let me know?

Your help is appreciated.

Best Regards,
Akihisa Tamazaki

Sean-san,

I got the comment of the customer.

1. schematics
/resized-image/__size/808x549/__key/communityserver-discussions-components-files/196/8304._21714C98_.jpg

2. IN+,IN- condition
=> VIN-:3.09 V, VIN+:2.81 V at CT=10 nF  (not tied to GND)
(Reference: Saw wave with REFOUT=4.94 V, VCT=0 to 3.5 V)

3 The customer checked the effect of setting the output to push-pull configuration
Measured dead time when output pins "EMIT1 (11 pins)" and "EMIT2 (14 pins)" are raised
The result is the same as when the output is connected.

4. Since the voltage difference between VIN- and VIN+ was not very large from the result of 2(IN+,IN- condition),  the effect of the in-/in+ pin was confirmed by increasing the voltage difference, then measure dead time when R3 is removed in schematics.
The value was close to the specification.
(Reference: VIN-=4.15V, VIN+=0V)
,

In above situation, they have some questions.

1)  How does the dead time exceed the specification in the customer schematics?
2)  How should “in+” and “in-” be terminal treated when the error amplifier function is not used?
Also, in their schematics, the COMP pin is connected to in+, is there any problem with how to use it?

Would you please advise?

Best Regards,
Akihisa Tamazaki

Sean-san,

The customer mistook to send me the documents. The attached schematics is correct.
IN+ is connected with Vpin9 (COMP), and IIN-(IN-) is not connected with Vpin9(COMP)

/resized-image/__size/802x544/__key/communityserver-discussions-components-files/196/030503.png

Is it possible  to tie IN+ to COMP? Is it mistake?
If it is no problem, I will ask the customer to compare Vpin9 and VPin 7 and  vary the voltage on Pin9.

Best Regards,
Akihisa Tamazaki

 

Sean-san,

Let me contact with you by email directly. Because some information of the customer increased.
Let me close this thread.

Best Regards,
Akihisa Tamazaki

Good, thanks.