SA5532A: Can SA5532 swing rail to rail input/output

Koyo Asaishi

Part Number: SA5532A
Other Parts Discussed in Thread: PCM1795, , OPA1678, TL974, OPA1679, SA5532

Hi team,

This is very urgency question because customer have to fix a device for I/V transition of PCM1795 due to AKM issue.
Could you please help to answer ASAP?

Their specification is that power is +8V/GND and center voltage at output is +2.5V.
The output of PCM1795 will be 4mA pk to pk and they want to swing with 2.8V pk to pk.

Is SA5532A rail to rail input/output?
I don't think this is rail to rail because this device is bipolar structure and following spec shows 2V at upper side and bottom side can't be used.

Is my understanding correct?
How about input rail?
I would like you to inform this device can achieve their specification.

Best regards,
Koyo

over 3 years ago

0 Jerry Madalvanos over 3 years ago

TI__Mastermind 27041 points

Hello Koyo-san

The SA5532A is not rail to rail input or output. Could you give the full specs you need, or is the main care-about rail to rail input-output? I've linked two searches below showing rail to rail input output amps in general purpose amplifiers and in audio amplifiers respectively.

https://www.ti.com/amplifier-circuit/op-amps/general-purpose/products.html#~p78=In;Out

https://www.ti.com/amplifier-circuit/op-amps/audio/products.html#~p78=In;Out

Best,
Jerry Madalvanos

0 Koyo Asaishi over 3 years ago in reply to Jerry Madalvanos

TI__Intellectual 1810 points

Hello Jerry,

Rail to rail input/output is not necessary, but they want to realize following specification.

"Their specification is that power is +8V/GND and center voltage at output is +2.5V.
The output of PCM1795 will be 4mA pk to pk and they want to swing with 2.8V pk to pk."

Following picture shows their output specification.
My question is that is this device able to realize the output with +8V VDD?

If 2V at bottom side can't be used, this output can't be realized.
In this case, could you suggest proper device?

Here is the system that they will design for I/V conversion. (extracted from PCM1795 datasheet)

Best regards,
Koyo

0 Jerry Madalvanos over 3 years ago in reply to Koyo Asaishi

TI__Mastermind 27041 points

Koyo-san,

I apologize for my lack of clarity. I understood the output voltage requirements, but was asking specifically for any other specifications needed such as bandwidth, cost, quiescent current, slew rate, THD, etc. If you require an audio amp for this circuit, OPA1678 is a dual channel op amp that has a rail to rail output.

I noticed you asked about a 2 channel op amp but the schematic shows a quad channel op amp. If you are looking for a quad channel op amp, OPA1679 or TL974 can meet your output swing requirements, also these can save you some board space without the requirement for a compensation capacitor.

Again, please feel free to use the ti.com search tools to help you find the best product for your customer's needs.
https://www.ti.com/amplifier-circuit/op-amps/audio/products.html#p1261max=8;48&p480=2;4&sort=p1130;asc

Best,
Jerry

0 Koyo Asaishi over 3 years ago in reply to Jerry Madalvanos

TI__Intellectual 1810 points

Hi Jerry

You mean SA5532 cannot realize the output?

If so, I will look for proper devices.

Anyway I know only bandwidth specification as 100kHz.

Best regards

Koyo

0 Jerry Madalvanos over 3 years ago in reply to Koyo Asaishi

TI__Mastermind 27041 points

Koyo-san,

From what I can tell from the datasheet, I would not expect the output to be correct if your output voltage is 2.8V p2p centered at 2.5V. If you could shift up the voltage away from the rails (for example, 2.8V p2p centered around 4V) the SA5532A would still work. I don't know if your output voltage must be as you have described.

If you look at the functional block diagram from the datasheet, and you assume two diode drops for the output transistors, that's 1.4V from the bottom rail. This is already violating your proposed output voltage. I would look for a device with a rail to rail output stage, or that can output voltages to VCC.

Best,
Jerry

Audio

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SA5532A: Can SA5532 swing rail to rail input/output