How does the schematic diagram work?

我是一个小小白

How does the schematic diagram work? [Copy link]

 

 

chunyang

The circuit is wrong, what is the purpose of the Power part?

chunyang

The original poster did not explain what the P1 input is, so we can only guess. If it is two power sources from different sources, then the expression is incorrect and the circuit cannot be established without it. If it is AC input or non-polarity power input, then the diagram does not show the necessity of Q1 and Q2. Therefore, first clarify the actual circuit or design purpose.

qwqwqw2088

The DC-DC part is a typical Buck circuit of a 5-pin chip.

What is the control of the P1 preamplifier in the Power section?

我是一个小小白

chunyang posted on 2020-9-3 21:40 The original poster did not explain what the P1 input is, so we can only guess. If it is two different sources of power, then the expression is wrong, and it cannot be established without a circuit. If it is an alternating...

The input is a pulse signal, which can be understood as the following picture

我是一个小小白

qwqwqw2088 posted on 2020-9-3 22:41 The DC-DC part is a typical Buck circuit of a 5-pin chip. What is the control of the P1 pre-stage of the Powe part?

The input is a pulse signal, which can be understood as the following picture

maychang

I am a little white posted on 2020-9-4 08:17 The input is a pulse signal, which can be understood as the following picture

This waveform still cannot explain the problem of the two VIN numbers in the left figure on the first floor. Note that the two VINs are connected together in the circuit.

maychang

I am a little white posted on 2020-9-4 08:17 The input is a pulse signal, which can be understood as the following picture

In addition, the socket P1 has two pins, but the author only drew the waveform of one of the pins, and did not specify which pin this waveform is for.

chunyang

I am a little white posted on 2020-9-4 08:17 The input is a pulse signal, which can be understood as the following picture

Still not clear...

我是一个小小白

chunyang posted on 2020-9-4 15:40 Still not clear...

It's first high up and low down, then high down and low up.

我是一个小小白

maychang posted on 2020-9-4 15:27 Such a waveform still cannot explain the problem of the two VIN labels in the left picture on the first floor. Note that the two VINs are connected together in the circuit.

First it's high up and low down, then it's high down and low up, but not at the same time.

chunyang

I am a little white and posted on 2020-9-4 15:48 It is first high up and low down, then high down and low up

That is definitely wrong. There is not even a reference point. If the signal source shares a common ground with your circuit, you must draw it out, and it should be connected using a 3-pin connector.

maychang

I am a little white published on 2020-9-4 15:48 It is first high up and low down, then high down and low up.

Then, the signal between the two pins at the socket P1 is floating relative to the ground.

In this way, the four diodes D1 to D4 can charge the capacitors C1 and C3, and the voltage across the two capacitors C1 and C3 is close to the peak value of the input signal.

But no matter what the signal at P1 looks like, it cannot explain the problem of the two VINs on the left side of the first floor picture. As chunyang pointed out on the second floor: "What is the purpose of the Power part?"

我是一个小小白

chunyang posted on 2020-9-4 16:03 That is definitely wrong. There is not even a reference point. If the signal source shares the same ground with your circuit, you must draw it out, and it should be connected with a 3-pin connector.

I think Q1 is about flow expansion and Q2 is about protection.

maychang

I am a little white and posted on 2020-9-4 16:10 I think Q1 is to expand the flow, and Q2 is to protect.

Q1 cannot expand current. The current output from the collector of Q1 cannot exceed the current provided by diode D2.

The collector of Q1 should not be connected to the upper end of C3.

chunyang

I am a little white and posted on 2020-9-4 16:10 I think Q1 is to expand the flow, and Q2 is to protect.

Whose flow is being expanded? How is it being expanded? Who is being protected? How is it being protected?

Opinions need to be supported by evidence.

我是一个小小白

This is a practically verified circuit, it is feasible and can obtain a regulated output. Please take a look at the principle and analyze it.

jack8023

I actually found the picture I drew. This is a polarity pulse and polarity detection circuit:

jack8023

When P1-pin2 has a positive pulse, the electricity is first rectified and stored in C1, and then waits for the arrival of the positive pulse of P1-pin2. When P1-Pin2 inputs a positive pulse, it is rectified and stored in C3, and then DCDC U3 is started, and then DVCC outputs the working voltage. Subsequently, DVCC triggers Q2 to turn on, so that the electricity previously stored in C1 flows to DCDC (U3) through Q2 and is used.