PSOC5 PGA max output current

[Ashaabanahmed]

What the max output  current that  PSOC5 PGA  can source ?

[odissey1]

The PGA is intended for internal use mostly. Probably less than 1mA.

[Len_CONSULTRON]

@Ashaabanahmed ,

All PSoC PGA (UDB) features must go through a GPIO pin if used external to the PSoC.  Therefore, it is the current limitation of the GPIO pins being used.  4mA source, 8mA sink unless you use the SIO pins which are 4mA source up to 25mA sink.

[BiBi_1928986]

Hi Len.

I agree with you that UDB and other logic level functions, that go through GPIO pins, have the drive levels you mentioned.

But, PGA and other analog signals go to the GPIO pin via either the Analog Mux or the Analog Global bus.  This bypasses the digital GPIO output circuitry completely.  A comparator might be able to be routed to the digital drivers, but that's an exception.

The only spec in the datasheet relating to output current at a GPIO pin, from an analog component, is the output voltage swing spec Vsrc, 250uA with 100k Ohm load.

It would be good if Cypress/Infineon were to provide the real output current spec for PGA signals.

That said, an op-amp can sink/source 25mA when Vdda > 2.7V.  And that alone is a good reason to follow a PGA with an op-amp when driving a GPIO pin.

[Len_CONSULTRON]

@BiBi_1928986 ,

Oops.  you are correct.   I quickly read the post and replied too quickly.   PGA = Programmable Gain Amplifier.   My brain was thinking PGA = Programmable Gate Array.

[DennisS_46]

Odissey and my friend Len are both wrong.
The maximum current can be easily found in the datasheet 001-84932:

This data is at Vdd = 2.7 V; the opamp can drive a little harder Vdd = 5.0V.
If you don't have to drive all the way to the rail, the chip can easily drive 25 mA.
This has nothing to do with GPIO drive for digital outputs.
---- Dennis Seguine, THE senior PSoC apps engineer (and one of the authors of the original PSoC5 spec)

[BiBi_1928986]

Hi Dennis.

The original post was asking about PGA, not op-amp.
Can you provide the PGA output current spec?

[DennisS_46]

BiBi:
From the same device datasheet:

From this we can compute sourcing current Iout =(Vdd-0.15 - Vdd/2)/100k = 23.5 uA at Vdd = 5.0V. Similarly for sinking current. The output under load = 250 uA drops to sourcing Vdd - 0.3V and sinking to 0.3 V. So the question is: how much drive current is needed?
---- Dennis

[DennisS_46 · Accepted solution]

BiBi. et al:
I made a significant error, my apologies. The individual opamps can drive up to 25 mA, but the output current of the PGA, which is a different block is indeed limited to about 250 uA. These blocks have a much weaker drive capability; why? because the silicon area devoted to output drive (as in the opamp) is replaced by the resistor array and its collection of switches. You can't have both in PSoC5lp. If you need to drive significant external current from PGAs, they should be buffered by an opamp. In comparison, the PGA in PSoC4100PS or analog coprocessor can drive direct to pin, but is limited to 10 mA.
Again, sorry for my earlier error.
---- Dennis

[LeoMathews]

Hi @Ashaabanahmed  ,

Thread was locked due to inactivity for long time, you can continue the discussion on the topic by opening a new thread with reference to the locked one. The continuous discussion in an inactive thread may mostly be unattended by community users.

Thanks and Regards,
Leo