From 6223cbc5ecdd1419e1265c3f7cb5394dc6575af9 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Henrik=20Alse=CC=81r?= <henrik.alser@me.com> Date: Sun, 17 Jan 2021 22:33:40 +0100 Subject: [PATCH] LDOs --- README.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/README.md b/README.md index e53a0fd..3e22506 100644 --- a/README.md +++ b/README.md @@ -117,9 +117,9 @@ One easy way to get power to your project is through USB. It can deliver up to 1 ### 9) 3.3v Power Supply -The MCU needs a stable voltage. A common for digital components is 3.3v. To this end we will use a fixed LDO (low dropout) regulator, with a 5v input (powered from the USB connector) and 3.3v output. We will use the (_HA_) +The MCU needs a stable voltage. A common for digital components is 3.3v. To this end we will use a fixed LDO (low dropout) regulator, with a 5v input (powered from the USB connector) and 3.3v output. We will use the [AP2125N-3.3TRG1](https://www.elfa.se/en/ldo-voltage-regulator-3v-360ma-sot-23-diodes-incorporated-ap2125n-3trg1/p/30041163) -Look in the datasheet for reference values for decoupling. Later we will design the power supply for the PWM3389 sensor, which is a bit trickier. +Look in the [datasheet](https://www.elfa.se/Web/Downloads/_t/ds/AP2125_eng_tds.pdf) for a typical application circuit. Later we will design the power supply for the PWM3389 sensor, which is a bit trickier. ### 10) PWM3389DM-T3QU Schematic Symbol @@ -141,9 +141,9 @@ Hint. Never, never ever, change the grid settings when placing the pins in the s As you see in the PWM3389DM-T3QU datasheet and reference schematics, the sensor requires a 1.9v power supply. This is much less common voltage (try finding one from Elfa or rs-online) and you will likely fail. -To that end, you can use an adjustable regulator (_HA_). +To that end, you can use an adjustable voltage regulator, such as [MIC5235YM5-TR](https://www.elfa.se/en/ldo-voltage-regulator-24-20v-sot-23-microchip-mic5235ym5-tr/p/30099685), which will let you set your desired output voltage using external resistors. -The equation for the output voltage can be found in the datasheet for (_HA_).Hint: A good rule of thump is one 100nF ceramic capacitor to each power-pin. Hint2: The smoothing capacitor should be an electrolytic capacitor, hence polarized. +The circuit and equation for calculating the resistor values needed to acheive the desired the output voltage (1.9V) can be found in the [datasheet](https://www.elfa.se/Web/Downloads/_t/ds/MIC5235YM5-TR_eng_tds.pdf) for the regulator. Here you will also find information about input- and output capacitor values needed for proper operation. Once you have added the 1.9v power supply you can add a new power net, and connect that to your PMW3389 component. -- GitLab