Problems with TPA series amplifier chips

shaorc

【Ask if you don't understand】I have looked at two TPA series digital power amplifier chips, TPA3221 (Figures 3 and 4) and TPA3255 (Figures 1 and 2) The manuals show that both of them can have dual-channel differential inputs Figures 3 and 4 clearly show that 1N1-P and IN1-M are a pair of differential signal inputs,1N2-P and IN2-M are another pair of differential signal inputs However, the four inputs (A/B/C/D) in Figures 1 and 2, the peripheral circuit seems to directly form inputA and inputB into a pair of differential inputs and the internal structure diagram (Figure 2) looks like four inputs cascaded together. How can we tell which two inputs are a pair of differential inputs? It's not as clear as the pairing in Figure 4? Picture 1 Picture 2 Picture 3 Picture 4

chunyang

The drawing methods of Figure 2 and Figure 4 are the same. The latter is just a combination of some units. The internal circuit diagrams of the two are exactly the same. As for whether the details of the internal circuit are the same, it is impossible to determine. As for how to tell which two are a pair, just look at the pin markings. You don’t need to care about the internal circuit. In fact, many of these amplifiers have independent internal channels. You can define it as 4-channel independent output. But if the polarity is marked on the pin and there is no mention of independent output, that is, only dual-channel output or mono output mode, it means that there are constraints on the internal circuit and it is no longer 4 independent channels.

shaorc

chunyang posted on 2019-3-21 12:51 The drawing methods of Figure 2 and Figure 4 are the same. The latter is just a combination of some units. The internal circuit block diagrams of the two are exactly the same. As for the internal circuit...

I have a design selection question. I would like to ask about the CMUTE with a line on a pin of TPA3221. Its description is Figure 1, and the recommended application is Figure 2 I don't know which parameters to use to select the model of the N-type MOSFET connected to CMUTE. From the description of Figure 1, the function of this pin is to mute the amplifier. When the crossed-out CMUTE is at a low level, this mode can be turned on. That is, the N-type MOSFET is turned on, and the crossed-out CMUTE is pulled low. To achieve the purpose, the external signal CMUTE is at a high level. So how do I select the model of the MOSFET? Figure 1 Figure 2

maychang

shaorc posted on 2019-3-22 17:24 I have a design selection question. I would like to ask about the CMUTE with a line on a pin of TPA3221. Its description is Figure 1, and the recommended application is Figure 2...

"So how do you choose the MOSFET model?" It is estimated that any model of low-power N-channel MOSFET can be used.

chunyang

shaorc posted on 2019-3-22 17:24 I have a design selection question. I would like to ask about the CMUTE with a line on a pin of TPA3221. Its description is Figure 1, and the recommended application is Figure 2...

An external MOS tube is required only if touch control is required. Unless otherwise specified, any model with the same polarity can be used.

shaorc

maychang posted on 2019-3-22 18:43 "So how do you choose the type of MOSFET?" I guess any type of low-power N-channel MOSFET can be used.

Thank you. After choosing an NMOS, should I use it directly according to the diagram on the 3rd floor, or should I connect a pull-up resistor? I should use it directly according to the recommendation in the diagram.

shaorc

chunyang posted on 2019-3-23 16:29 If touch control is required, an external MOS tube is required. Unless otherwise specified, any model with the same polarity can be used.

Thank you

maychang

shaorc posted on 2019-3-25 09:02 Thank you. After choosing an NMOS, should I use it directly according to the diagram on the 3rd floor, or should I connect a pull-up resistor? It should be directly according to the diagram...

"After choosing an NMOS, should I use it directly according to the diagram on the 3rd floor, or should I connect a pull-up resistor? It should be directly according to the diagram." You can connect a pull-up resistor, and the pull-up resistor value should not be too small. However, in general, there is no need to use pull-ups, just use it according to the diagram.

shaorc

maychang posted on 2019-3-25 09:16 "After choosing an NMOS, should I use it directly according to the diagram on the 3rd floor, or should I connect a pull-up resistor? It should be directly according to the recommendation in the diagram...

OK, if a pull-up resistor is needed, is the connection method as shown in the figure below? You said that the pull-up resistor cannot be too small, this is to limit the current, the limiting current cannot be greater than the ID of the NMOS, but this is also related to the size of the external power supply (here is 5V)

maychang

shaorc posted on 2019-3-25 09:37 OK, if a pull-up resistor is needed, is the connection as shown below? You said that the pull-up resistor cannot be too small, this is to limit the current, the limiting current cannot be greater than NM ...

The pull-up resistor is connected like this. However, as mentioned before: Generally, there is no need to use a pull-up. This is because the MOS tube is only used as a variable resistor. When the MOS tube is completely turned off, the drain to the source is equivalent to a large resistance (greater than 1 megohm), and when the MOS tube is fully turned on (entering the variable resistance area), the drain to the source is equivalent to a very small resistance (about several ohms for low-power MOS tubes and only tens of milliohms for high-power MOS tubes). The function of this pin of the chip is to mute. When the MOS tube is completely turned off, it has no effect on the audio signal. When the MOS tube is fully turned on, the pin is grounded through a 1 kilo-ohm resistor, attenuating the audio signal to a very small level to achieve the purpose of mute. Therefore, it is not important to have a pull-up resistor or not. The pull-up resistor only makes the working current of the MOS tube slightly larger, and it has no current limiting effect.

shaorc

maychang posted on 2019-3-25 09:47 The pull-up resistor is connected like this. However, as mentioned before: In general, there is no need to use a pull-up. This is because the MOS tube is only used as a...

[1] When the MOS tube is fully turned on (entering the variable resistance zone) I have heard you say this many times before. When the MOS tube is fully turned on, the resistance between the drain and the source is very small. It is easy to understand that the conduction is achieved, but at this time the resistance should be a fixed and very small value. How is the "variable" in the "variable resistance zone" reflected here? Is Rds determined according to the voltage of the external power supply at the drain, so it is said to be variable? [2] When the MOS tube is fully turned on, the pin is grounded through a 1 kilo-ohm resistor, attenuating the audio signal to a very small value to achieve the purpose of mute. The pull-up resistor only makes the working current of the MOS tube slightly larger. Is the audio signal attenuation mentioned here because the signal is dissipated in the 1K ohm resistor?

chunyang

shaorc posted on 2019-3-25 10:44 [1] When the MOS tube is fully turned on (entering the variable resistance area), I have heard you say this many times before. When the MOS tube is fully turned on, the resistance between the drain and the source is very small...

The mute function is realized by the internal circuit. The mute control pin is just a logic input port. Its level determines the opening and closing of the mute circuit inside the chip. There is no such thing as "the signal dissipates on the 1K resistor". Similarly, if the external pull-up resistor is not mentioned in the device manual, it does not matter whether it is added or not. The mute control pin should have a built-in pull-up, otherwise the device manual will inevitably require it to be added externally.

shaorc

chunyang posted on 2019-3-25 12:26 The mute function is realized by the internal circuit. The mute control pin is just a logic input port. Its level determines the opening and closing of the mute circuit inside the chip...

The mute function is realized by the internal circuit. The mute control pin is just a logic input port. Its level determines the opening and closing of the mute circuit inside the chip This is the functional schematic diagram of TPS3221 Figure 1 Figure 2 is the peripheral circuit of mute CMUTE 【1】According to your meaning, Figure 2 The high or low level of the CMUTE signal on the far left determines the high or low level of the PIN17 pin (with the underlined CMUTE) The high or low level of the latter determines whether the chip is in silent mode? [2]The signal source of the CMUTE on the left is the control chip, such as STM32? Figure 1 Figure 2

shaorc

maychang published on 2019-3-22 18:43 "So how do you choose the model of MOSFET?" It is estimated that any model of low-power N-channel MOSFET can be used.

First post Figure 3 TPA3221's PIN10 reset pin RESET does not provide the peripheral circuit. The idea of building a reset circuit by yourself is to select a reset chip based on the reset timing and reset signal pulse width, and output the RESET signal to PIN10. Looking at the chip manual, it says in the figure below that the rising edge of the RESET signal and the falling edge of the FAULT signal are at least 4ms apart. How can the pulse width of the reset signal be seen from the timing diagram given in the manual?

maychang

shaorc posted on 2019-3-29 09:39 First post 3 PIN10 of TPA3221 Reset pin RESET does not provide peripheral circuits. The idea of building a reset circuit by yourself is to build a reset circuit based on the reset timing and reset...

In the figure below, it is said that the rising edge of the RESET signal and the falling edge of the FAULT signal are at least 4ms apart. How can we see the pulse width of the reset signal in the timing diagram given in the manual? In the timing diagram given in the manual, the RESET signal is the third line curve, and the FAULT is the fifth line curve. The figure only shows the rising edge of RESET, and does not show the falling edge of the FAULT signal.

shaorc

maychang published on 2019-3-29 10:55 In the figure below, it is said that the rising edge of the RESET signal and the falling edge of the FAULT signal are at least 4ms apart. How can we tell the reset signal from the timing diagram given in the manual...

So in this case, we cannot see the length of the reset pulse width. How do we choose the reset chip?

maychang

shaorc posted on 2019-3-29 11:03 So in this case, you can't tell the length of the reset pulse width. How do you choose the reset chip?

Look carefully in the chip manual, there should be an explanation. If there is no explanation, it means that there is no strict requirement for the reset pulse width. You might as well choose a wider reset pulse.

shaorc

maychang posted on 2019-3-29 11:32 Look carefully in the chip manual, there should be an explanation. If there is no explanation, it means that there is no strict requirement for the reset pulse width. You might as well make the reset pulse...

OK, then you should choose a larger one. It is not clearly stated that this is a reset chip used in a design case. Is the time on the left the reset pulse width?

zhuyebb

No reply, no forum

maychang

shaorc posted on 2019-3-29 11:52 OK, then you should choose a larger one. It is not clearly stated that this is a reset chip used in a design case. Is the time on the left the reset pulse width? ...

This is a reset chip used in a design case. Is the time on the left the reset pulse width? Yes.