topic Re: NVT2003DP,118, Pullup resistor requiremnet in 8-bit Microcontrollers

NVT2003DP,118, Pullup resistor requiremnet

a_kumar — Wed, 19 Aug 2020 09:24:55 GMT

HI NXP team,

I am Abhishek, design engineer from krypton solutions Pvt Ltd. we are using one level translator Part No-NVT2003DP,118. I have to translate the signal from 3.3V to 1.8V ie I have connected the VrefB- 3.3V and VrefA-1.8V, The maximum current consumption is 15mA.

Question -

I have provided the Pullup resistor (232Ohm) at the VrefB side. I want to know ie Pullup resistor is required at the VrefA side.

As the datasheet is showing ie pullup is not needed at the VrefA side.

My suggestion:-

I have found some point is pullup is not required the VrefA side.#

Question2:-

It is mentioned the both I/O are the open drain in case of level translator , So why pullup resistor is not required at the VrefA side?

Please reply it asap.

Thanks

Abhishek

Re: NVT2003DP,118, Pullup resistor requiremnet

reyes — Thu, 20 Aug 2020 03:12:38 GMT

Hi,

When using open-drain devices, it is always required to use pull-up resistors at B-side, and they must be sized so as not to overload the output drivers. When using the PCA9306 or NVT20xx family, if VCC(B) - VCC(A) < 1 V, then pull-up resistors are required on A-side to pull up the An outputs to VCC(A). It is important to note that if pull-up resistors are required on both the A-side and B-side, the equivalent pull-up resistor value becomes the parallel combination of the two resistors when the pass transistor is ON. If VCC(B) - VCC(A) ³ 1 V, then pull-up resistors on the A-side are not required.

So, in your case, since VCC(B) is 3.3V and VCC(A) is 1.8V, then 3.3V-1.8V = 1.5V which is higher than 1.0V, so, pull-up resistors on the A-side are not required.

Regards,

Jose

Re: NVT2003DP,118, Pullup resistor requiremnet

a_kumar — Thu, 20 Aug 2020 08:05:32 GMT

Hi Jose,

Thanks for your reply.

Your reply has cleared my doubt, but I have one confusion i.e. if I will add the pullup resistor at the both side (VrefA-1.8V & VrefB-3.3V) as per 3mA current consumption. Will it not cause any problem?

Please confirm me, I am attaching the schematic screenshot for your reference.

I also have one confusion, in the datasheet it is mentioned i.e. we need to put the RC for delay (2ms) for VrefB & EN pin, Is it necessary to put in the design?

Regards

Abhishek

Re: NVT2003DP,118, Pullup resistor requiremnet

reyes — Thu, 20 Aug 2020 23:33:02 GMT

Hi Abhishek,

No, it will not cause any problem if you add the pullup resistor at the both side (VrefA-1.8V & VrefB-3.3V).

Yes, please add the RC circuit, otherwise you may have some timing issues.

Regards,

Jose

Re: NVT2003DP,118, Pullup resistor requiremnet

CPalman — Mon, 11 Jan 2021 17:51:23 GMT

Hello,

The datasheet states "...and a pull-up of 197 ohm." (which is too low for most applications!) yes the circuit above has 1.1K resistors. What gives?