Alvaro Hernando

Problems with NVT2010

Discussion created by Alvaro Hernando on Oct 6, 2016
Latest reply on Oct 11, 2016 by Alvaro Hernando
Hello, I am testing the bidirectional voltage-level translator NVT2010 but I am not able to make it work as expected.
I have one MK22FN256VLL12 at 3.3 V and I need to convert the signals to 1.8 V. I am using the same circuit proposed in the datasheet, with VREFB = 3.3 V and VREFA = 1.8 V.
With the MK22FN256VLL12 GPIOs configured as outputs with output logic 1 in the initialization, if I connect only the 3.3 V side, don't connect 1,8 V and left A ports floating, the VREFA value is 2.8 V. I don't know it this is normal or not.
When I connect the 1.8 V to VREFA and A ports to GPIOs configured as inputs with no pull, VREFA value is 2.1 V and the conversion is done for 3.3 V to 2.1 V instead of 1.8 V.
I have tried also with inputs with pull-up and happened the same. In tek00015.bmp it could be seen VREFA in yellow (2.1 V), A1 in blue (2.1 V when high), VREFB (2.6 V) in pink and B1 in green (3.3 V when high).
With the MK22FN256VLL12 GPIOs configured as inputs with pull-up and on the other side GPIOs configured as outputs with no pull, VREF value is still 2.1 V and the conversion is done from 1.8 V to 1.8 V instead of 3.3 V. With 1.8 V, the MK22FN256 should not read a high level (VIH = 2.31 V), but it did.
In tek00008.bmp it could be seen VREFA in yellow (2.1 V), A1 in blue (1.8 V when high), VREFB (2.6 V) in pink and B1 in green (1.8 V when high).
I don't know what I am doing wrong so any help would be appreciated.
Many thanks.
Regards,
Álvaro

Outcomes