From 74e119b6e2ce33c3dc66ec078396dfac6314c6c4 Mon Sep 17 00:00:00 2001 From: jaseg Date: Sat, 30 Dec 2023 16:35:36 +0100 Subject: theme: Add static page search with pagefind --- content/blog/multichannel-led-driver/index.rst | 28 +++++++++++++------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'content/blog/multichannel-led-driver') diff --git a/content/blog/multichannel-led-driver/index.rst b/content/blog/multichannel-led-driver/index.rst index 86fab72..c4e17b8 100644 --- a/content/blog/multichannel-led-driver/index.rst +++ b/content/blog/multichannel-led-driver/index.rst @@ -40,7 +40,7 @@ good timing. .. raw:: html -
+
A visualization of PWM at different duty cycles.
Waveforms of two PWM cycles at different duty cycles.
@@ -96,7 +96,7 @@ on. .. raw:: html -
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A visualization of BCM at different duty cycles.
Waveforms of a single 4-bit BCM cycle at different duty cycles. This BCM can produce 16 different levels.
@@ -144,7 +144,7 @@ period, one pulse will reset the shift register and one will strobe the freshly- .. raw:: html -
+
From left to right, we see the STM32, one of the shift
         registers, and the LEDs and MOSFETs. The LED tape is driven to ground by the MOSFETs, which are in turn directly
         driven from the shift register outputs. The shift register is wired up to the STM32 with its clock and data
@@ -199,7 +199,7 @@ voltrage we saw on our oscilloscope on the LED tape.
 
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-    <figure>
+    <figure data-pagefind-ignore>
         <img src=
Bad ringing on the LED output voltage caused by wiring inductance. Note that the effect on the @@ -215,7 +215,7 @@ likely culprit. The figure below is the schematic used for the simulations. .. raw:: html -
+
The LTSpice schematic of one output of the driver,
         taking into account the shift register's output ESR and the wiring ESL.
The schematic of the simulation in LTSpice
@@ -228,7 +228,7 @@ driver. .. raw:: html -
+
The result of the LTSpice simulation of our driver output. The LED
         current shows similar ringing to what we measured using the oscilloscope. Interestingly, the gate voltage shows
         strong ringing, too. @@ -246,7 +246,7 @@ since the estimated ESL and stray capacitance of the wiring is probably way off. .. raw:: html -
+
Weak ringing on the LED voltage waveform edge at about 30%
         overshoot during about 20% of the cycle time.
Adding a resistor in front of the MOSFET gate to slow the transition damped the ringing somewhat, @@ -257,7 +257,7 @@ since the estimated ESL and stray capacitance of the wiring is probably way off. .. raw:: html -
+
The result of the LTSpice simulation of our driver output with an
         extra 100 Ohms between shift register output and MOSFET gate. Similar to the oscilloscope measurement the
         ringing is much reduced in its amplitude. @@ -273,7 +273,7 @@ cycle of the LED current is not at all equal to the 50% duty cycle of the excita .. raw:: html -
+
The result of an LTSpice simulation of the LED duty cycle without and
         with damping. Dampening widens the LED current waveform from 50% duty cycle with sharp edges to about 80% duty
         cycle with soft edges. @@ -283,7 +283,7 @@ cycle of the LED current is not at all equal to the 50% duty cycle of the excita .. raw:: html -
+
The gate voltages in the spice simulation above. The undamped
         response shows sharp edges with the miller plateau being a barely noticeable step, but with strong ringing on
         the trailing edge. The damped response shows RC-like slow-edges, but has wide miller plateaus on both edges
@@ -327,7 +327,7 @@ sensitive owing to their physically large die area.
 
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-    <figure>
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         <img src=
A plot of the measured brightness of our LED tape for each BCM period. The brightness values are normalized @@ -376,7 +376,7 @@ the resulting brightness curve below. .. raw:: html -
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@@ -432,7 +432,7 @@ Conclusion .. raw:: html -