Linked Questions

1
vote
1answer
510 views

What role is this Matched PNP Transistor and MOSFET pair playing in this circuit? [duplicate]

I'm trying to understand what exactly this power circuit is doing. The schematic below shows 5V in from USB. It is run through a fuse, and then there's some tricky PNP transistor stuff happening I can'...
3
votes
1answer
285 views

What does this Mosfet & Bipolar Transistor power circuit do? [duplicate]

I'm trying to design a raspberry pi HAT prototype and I came across this circuit below. I'm not familiar with power electronics but i'm curious of what this circuit is trying to accomplish. Any help ...
2
votes
1answer
105 views

What is the exact principle of this circuit? (PNP transistors and P-channel MOSFET) [duplicate]

I have this given circuit: I can see by the look of it that this is a power rail "choosing" circuit. When VBUS is applied and there is no ...
1
vote
0answers
138 views

Understanding the Raspberry Pi 3's power input circuit [duplicate]

I am trying to understand the Raspberry Pi Model 3's power input circuit, as seen here: However, I am stuck at the purpose/function of the centre subcircuit outlined in black. What I have gathered ...
-1
votes
1answer
106 views

What purpose does the following circuit have? [duplicate]

The circuit was pulled from a SBC schematic. VBUS_5V is the input power from the micro USB port. Ultimately I am attempting to figure out if there is current limiting between VBUS_5V and VDD_5V.
3
votes
5answers
382 views

Diode type with lowest drop voltage [duplicate]

I make a small solar energy harvester. I'm searching for the type of diode with lowest drop voltage. Any suggestion for the type of diode for me ? Thank you
1
vote
1answer
1k views

PMOSFET Ideal Diode for 24V

After some browsing I found transistor circuit very similar to my needs: Understanding an 'ideal' diode made from a p-channel MOSFET and PNP transistors Unfortunately its application is ...
1
vote
1answer
2k views

Block current flow in one direction with FET transistors

Is it possible to block current flow in one direction like a simple diode using FET transistors to avoid the voltage drop? simulate this circuit – Schematic created using CircuitLab I am not ...
1
vote
1answer
752 views

Equivalent ideal diode circuit analysis

I have been looking over multiple designs for ideal diodes using FET transistors such as the circuits from these posts: PMOSFET Ideal Diode for 24V Understanding an 'ideal' diode made from a ...
2
votes
2answers
163 views

Resistance of mosfet's internal diode

I am an IoT solutions developer and not an engineer, so please excuse my vocabulary if not upto the mark. I have used Mosfets such as FDD6637 and IRF9310 in my circuits for power switching and they ...
1
vote
0answers
779 views

Emitter-base voltage in ideal-diode circuit for voltages >5V

I stumbled over the circuit in the related question which accroding to the explanation and my understanding implements a comparator by means of two PNP transistors to pull the gate of the P-channels ...
-1
votes
2answers
170 views

Switching Between Two Power Supplies Without Reverse Current

I'm new to electronics, so I'm bound to have gotten something wrong. I'm designing a basic sensor and want it to be powered by USB by default, but use a lithium polymer battery when not connected via ...
0
votes
2answers
49 views

Stable LDO voltage when Vin goes down momentarily

I have an application where Vin comes from a battery pack (3V - 7V) but on occasion and under heavy load, Vin drops to just above 2V for ~ 1 seconds before recovering. There is a 3.3V LDO that ...
1
vote
1answer
133 views

Automatic Power Selection with MOSFET

I need a circuit which will automatically disconnect the battery from LOAD when ext. DC power is connected so that the battery won't get damaged. Theoretically a pair of diodes can solve this but ...
0
votes
1answer
98 views

Prevent current backfeed without power loss

I have a solar panel and an external power source feeding into a DC converter (U10) that are both used to feed a battery charger (U2): In a previous design I used 2 schottki diodes to prevent back ...

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