Capturing Transient Response on DS1054z - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: April 18, 2019, 11:46:30 pm
content: Hi,I'm working on a buck converter and am trying to do comparisons of simulation (with models of parts used) vs actual design. The Pspice simulation provided the following responsehttps://imgur.com/a/XfiV7jpI've got the circuit breadboarded and am trying to obtain that response on my DS1054z. I currently have the vertical divisions set to 5 volts and horizontal divisions set to 1ms. I've been reading through the trigger options of the manual but I am not having any luck obtaining the response. I was going through them and looking for which (if any) would trigger and hold after 5ms of waveform is captured. Does anyone have any suggestions?

author: rstofer
author_rank: Super Contributor
timestamp: April 18, 2019, 11:51:48 pm
content: Nothing attached...I would think you would want to trigger on some event or edge (rising or falling) and use Single Mode to get just one sweep. If you want 5 ms across 12 units, you probably want to see the time/div to 500 us. You will get 6 ms and that's probably close enough.You would also want to move the trigger horizontal point over to the left edge of the screen with the horizontal Position knob (right about time/division knob).

author: Mattjd
author_rank: Regular Contributor
timestamp: April 18, 2019, 11:57:00 pm
content: Quote from: rstofer on April 18, 2019, 11:51:48 pmDo you see the imgur now?

author: Mattjd
author_rank: Regular Contributor
timestamp: April 19, 2019, 12:00:08 am
content: Do you think timeout on the positive edge is the positive trigger?https://www.batronix.com/pdf/Rigol/UserGuide/DS1000Z_UserGuide_EN.pdfPg 5-24Right now I have 500us per division with the position all the way to the left. I have the trigger at 500mV utilizing the Timeout trigger to start counting when the positive edge crosses 500mV and go off after 5ms.It keeps holding at steady state.It triggers at steady state and I dont get to see the transients.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: April 19, 2019, 12:54:38 am
content: Your vertical divisions are set to 5V/div? And your maximum voltage on the simulation is a hair less than 4.8 V ? So you are trying to see the whole transient within a single vertical division?Maybe that's the problem.Set the volts per division to 1V/div, use single shot mode, set trigger vertically to slightly below peak expected voltage, do not set trigger all the way to the left yet. Let's get the peak captured, then we can change some settings to get a display similar to the Spice readout. Just use the normal edge trigger with default holdoff for now. Single shot, rising edge trigger, 1v/div vertically, 500 us horizontally.

author: Mattjd
author_rank: Regular Contributor
timestamp: April 19, 2019, 01:02:21 am
content: Quote from: alsetalokin4017 on April 19, 2019, 12:54:38 amOh jeezbus, I just realized that. I was still thinking in terms of the gate driver for the circuit thats outputting 15v pwm.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: April 19, 2019, 10:20:26 pm
content: Well, did you get a decent capture yet? I'd like to know if my suggested settings or similar actually worked for you.

author: Mattjd
author_rank: Regular Contributor
timestamp: April 20, 2019, 06:58:38 pm
content: Quote from: alsetalokin4017 on April 19, 2019, 10:20:26 pmIt did not, and I have not been able to get the transient captured at all.Thank you for the replies so far.

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: April 21, 2019, 01:28:46 am
content: OP, set time base ~ 1ms per division, set vertical to ~ 1V div, set channel to AC coupling, adjust trace to lower position on scope vert divisions and set trigger to lets say ~3~4V.My guess is you have a DC component that is pushing the waveform off the screen.

author: rstofer
author_rank: Super Contributor
timestamp: April 22, 2019, 08:38:12 pm
content: Have you tried Auto?It will usually get <something> on the screen and, if your signal actually starts at 0V, you trigger level can be quite low. Just move the trigger point down.I'm assuming a signal that repeats at some reasonable rate. Otherwise, use Single Shot.