Blackthorn & ChargerPro
ChargerPro
Hey, I've been puzzling over how some chargers suddenly spike when the device starts drawing more current—it's like a crime scene in circuitry. What’s your take on the hidden clues in those voltage jitters?
Blackthorn
The spikes you’re seeing are the charger’s way of saying “I’m under stress.” When the load suddenly demands more current, the internal switching circuitry ramps up, and the supply rail can dip or overshoot before it stabilises. Look for clues: a quick rise in current draws a voltage drop if the internal MOSFETs or the driver’s gate drive are slow; a sudden rise in ripple points to insufficient smoothing inductance or capacitor ESR; a brief overshoot followed by a sharp crash can mean the charger’s protection circuitry is tripping. So check the current sensing resistor, the bulk capacitors, and the switching frequency—those are the evidence you need to track down the culprit.
ChargerPro
Sounds spot on—those are the usual suspects. Try swapping that sense resistor for a low‑ohm, low‑ESR one, give the bulk cap a second look, and bump the switching frequency a notch if you can. If the spikes still dance, a small snubber or an extra inductor might tame the chaos. Remember, even the nicest chargers hate a sudden surge, just like a bad guy in a movie. Need help setting up a quick test setup?
Blackthorn
Sure thing. Grab a USB‑to‑USB meter that can log current and voltage at 1 ms intervals. Hook the sense resistor to the meter’s differential input, put the bulk cap in parallel on the rail, and set the switcher to a higher clock if it lets you. Run a short burst of 3 A draw, watch the waveform, and tweak the snubber values until the spikes shrink. If you hit a wall, we’ll dive deeper into the driver’s gate drive circuitry. Just keep the logs tidy and we’ll have the evidence in no time.
ChargerPro
Nice plan, let’s get that meter hooked up and keep the logs in a neat folder—evidence matters. Start with a 3 A burst, see how the voltage skids, then dial in a 0.1 µF snubber first. If the spikes keep crashing, we’ll pull the driver’s datasheet and look at the gate‑drive slew rate. Don’t forget to monitor the MOSFET junction temperature; a sudden spike often means the gate drive’s too slow and the device is overheating. Keep me posted on the readings—time to squash those spikes.
Blackthorn
Okay, pull out the 5 V USB‑to‑USB power meter, set it to log current and voltage every millisecond, and save the data to a folder called “spike‑logs.” Start the charger, bring it up to a 3 A load—think a phone or a small LED strip—then watch the voltage. It should drop a bit when the load kicks in. Then drop a 0.1 µF snubber across the charger’s output, re‑run the 3 A test, and compare. If the drop is still nasty, open the driver’s datasheet, check the gate‑drive slew rate, and if it’s sluggish, consider a faster MOSFET or a dedicated gate‑driver IC. While you’re at it, log the MOSFET’s junction temperature with a thermal camera or a thermocouple. Let me know the numbers, and we’ll tweak from there.
ChargerPro
Got it—meter ready, logs in “spike‑logs,” 3 A test underway. I’ll hit the 0.1 µF snubber, pull the gate‑drive data, and keep an eye on the MOSFET temp. When the numbers roll in, we’ll fine‑tune the whole thing. Hang tight, I’ll keep you posted.