Questions tagged [low-side]

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13
votes
3answers
1k views

Why is there a Schottky diode connected to the low-side switch

I am trying to understand the reason for having a Schottky diode for protection in a buck switch by reading here. To summarize, I can understand why two the switches should not be turned on at the ...
1
vote
1answer
77 views

Relay does not switch off

I have what I thought was a simple relay circuit but the relay is always on. This is the part of the project that is not working Q5 never switches off. To simplify it further I removed the relay and ...
1
vote
1answer
56 views

EMI and reliability considerations for low-frequency, low-voltage DC load drive

In my application I need to drive a 240W pure-resistive load with a nominal voltage of 24V. The input is a standard 280W AC-DC external power adapter, the Meanwell GST280A24. The load switch is ...
0
votes
1answer
40 views

EMI voltage ripple issue for low side NFET

Under some user suggestion, I decided to drive my 10-ohm load heater using a low side NFET. I put a 1k resistor (R1) at the NFET gate to reduce ringing. I got, before placing the resistor, a very bad ...
3
votes
4answers
97 views

Calculate temperature for low side switches?

I would like to know how to calculate the temperature (to see if I am still in a working range) for a low side switch. Hope you can help me there. I need to control 10 valves(12/24V - 500mA max. ea.) -...
1
vote
1answer
84 views

Problems with low-side MOSFET in 12V LED dimming switch

I'm pretty new to electrics/electronics. I'm sorry if I make dumb questions, and thank you for your time. I wanted to control my LED strip shipped from Ebay, which works well with 12V 2A DC adapter. ...
0
votes
1answer
81 views

Low-Side LED PWM - Constantly On

As a now-professional EE, I'm slightly embarrassed to be asking what I feel like is a simple question. But I'm stumped and google isn't giving me good answers. I'm trying to PWM a string of LEDs via a ...
0
votes
1answer
54 views

Verifying electric brake current with opto-isolated feedback

I would like to find a way to sense (or detect) current through an opto-coupler. This opto is used to power an electromagnetic brake, but depending on the type of brake the current through it can ...
0
votes
1answer
261 views

Back to back N-MOSFET on low side

I would like to disconnect the current in the system with a battery (using N-MOSFET in a back to back configuration). I would like the circuit to be on the low side and without a driver. At this point,...
2
votes
1answer
62 views

Define the purpose of these components in the operation of this low side driver

I am trying to understand the operation of the following low side driver circuit I found in a schematic of an old pinball machine (redrawn for clarity): L1 is a Solenoid and Q1 is a Darlington BJT (...
0
votes
2answers
61 views

BLDC low-side gate oscilations

I am developing the BLDC motor controller board and I have problems with low-side gate driving. I am using MC33035 BLDC motor controller. PWM for speed control is fed into low-side MOSFETs. High-side ...
0
votes
0answers
48 views

IC with configurable output : high-side, low-side, push-pull

As the title mentions, I need to implement a design that would require an IC that can be driven in high-side, low-side, or push-pull configuration. The main purpose for this is that I need to drive ...
1
vote
1answer
78 views

In this low side switching schematic does the 10k resistor play any role?

I've been given this schematic to review it (I'm working on a formula student team.) It is used for cutting off the power to a motor through a N-mosfet (NCV8402A). The 12V are being supplied through ...
2
votes
0answers
83 views

How to drive MOSFET switches in a cascaded hybrid modular multilevel converter using a half-bridge driver "IR2103S"

I am trying to drive the MOSFET switches in a cascaded hybrid modular multi-level converter as shown in Fig. 1. Fig. 2 is used here to simplify the circuit and to present the problem (let's focus on ...
0
votes
0answers
46 views

How to make a HIGH pin on ESP8266 go LOW when device is turned off using a low side switch?

I ran into this issue while working with WeMos D1 Mini and Adafruit's timer board. I had an N-channel MOSFET that was driven by the timer's DRIVE pin. When ESP was done doing its thing it would ...
5
votes
2answers
368 views

Low-side switch MOSFET cannot deliver full voltage

I have designed a portable lens heater prototype. Using: 18650 Li-ion battery Arduino ProMicro (3.3V , 8MHz) by adafruit (https://www.sparkfun.com/products/12587) Push button switch PMV16XN N-channel ...
1
vote
1answer
183 views

Low-side current sensing, raising the ground?

One of the main reasons why we don't use low-side current sensing for PSUs is that we want the ground to be, 'ground'. adding a shunt resistor will rise the ground slightly higher. In real world ...
0
votes
3answers
745 views

Mosfet Driver - High Side Output Problem

I've been trying to make a 3 phase inverter to drive a BLDC motor. Mosfets : IRF3205 Driver : IR2101 Supply voltage for FETs and drivers : 12V BLDC : https://media.digikey.com/pdf/Data%20Sheets/...
1
vote
1answer
321 views

Why does the PWM signals amplitude drop once connected to low-side n-mosfet switch?

I am applying a 3.3 V pwm signal to a circuit similar to the following (Credit: Olin Lathrop): I am using an IRLR024N N-MOSFET, which switches if i connect the gate to the 3V3 pin of my ...
1
vote
0answers
278 views

How to isolate a RLC circuit with MOSFET switches?

I'd like to isolate, with high-side and low-side switches, a RLC circuit after the inductor has been energized with a current of 2-3A from a 12V source (see sketch). When the RLC circuit is isolated ...
0
votes
1answer
746 views

Measuring pwm output from low side FET with oscilloscope

I have a n channel MOSFET controlling a high current LED panel. The FET is driven by a FET driver, which is itself driven by a MCU pin. I am using PWM to control the LED brightness. I want to double ...
0
votes
1answer
140 views

HO defaults "On" on high side/low side driver

I have an application where I need to drive 2 piezoactuators in a push-pull arrangement (voltage 180deg out of phase with each other) where the charge/discharge time is about 50 microseconds and the ...
0
votes
1answer
901 views

What is a (side) current alarm?

On the technical sheet of a motor controller integrating two BTS7960B (picture below), the description of the 8 PINs on the board is as follows: RPWM: Forward level or PWM signal input, active HIGH ...
0
votes
1answer
502 views

Can I drive a Low-Side MOSFET from a High-Side Driver?

I'm working on a power electronics project where it involves driving 4 different MOSFETs, (3 HighSide and 1 LowSide). Rather than using a different IC for the LowSide driver, I am thinking about using ...
0
votes
2answers
212 views

Current sense amplifier for high voltage (100-150V) low current (20 mA) application [closed]

I have an application where I need to measure the current on a relatively high voltage rail. The problem is that the current on the rail is quite low, only about 20 mA. Because of the high voltage, ...
4
votes
3answers
843 views

H-bridge low side current sensing: Current signal with oscillation why?

my problem is the following: I am using two DRV8842 H-bridge ICs to control 2 different brushed DC motors, my intention is to use a PI controller for the current loop. The schematic looks like this: ...
1
vote
1answer
168 views

IR2133 Bridge driver not working as expected

I want to use the IR2133 to drive a mosfet rectifier. I have setup as in the circuit below The probelm is (take first high side fet as example) that the signal that appears on HO1 is exactly the same ...
0
votes
1answer
189 views

Low-Side Switch MOSFET Drain Voltage Drop in OFF state?

I'm trying to replace a normally open switch with a low-side switch mosfet. The drain of the mosfet is connected to an input pin of a non-modifiable 3.3V MCU. Prior to my changes to the setup the ...
0
votes
1answer
517 views

high side vs low side current sensing in isolated bench power supplies, does it matter?

I'm trying to make a couple of mains isolated, transformer based, bench power supplies. Considering that the current sense resistor will be in the PSU box and external loads will not have access to ...