MC3664 - TPL

[Patrick_Pavle]

Dear Community, 

I wanted to test the MC3664 with an 8-bit message to see what it looks like in TPL.

blue - SCLK

green - MOSI

yellow/purple - TPL 

This is what the signal looks like before the Pulse - HM2103NLT

The MOSI bit message is 11001101. In the TPL you can see start of message and end of message but  only 7 bits in between. In the TPL are only the bits: 1001101.

This is what the signal looks like after the Pulse - HM2103NLT

TPL is not in the voltage range between 3.75 and 1.25

So I have the problem that the TPL signal is not in the voltage range and 1 bit is lost

best regards,

Patrick

[JozefKozon]

Dear Patrick,

could you please check the clock signal? Connect the probes on the CSB_TX, SCLK_TX and on both RDTX+/RDTX- pins. Please send the data on the DATA_TX pin. Please refer to the Figure 6. in the MC33664 datasheet. Please check if the timings are according to the Table 6. in the MC33664 datasheet. Unfortunately it's not possible to read the timings from the scopes you shared. 

How you measure the RDTX+/RDTX-. Are you measuring them against the AGND? 

With Best Regards,

Jozef

[Patrick_Pavle]

Dear @JozefKozon ,

the green one MOSI ist DATA_TX.

I have found the error why a bit was missing. Because of the time between CSB-TX and SCLK_TX which was too short.

However, the voltage levels still do not match.

Yes, I measure RDTX+/RDTX- against AGND

 

[JozefKozon]

Dear Patrick,

ok. Thank you for confirmation. From the scope, the RDTX+/- voltage span looks to be correct. Could you please try to measure the RDTX+/- signals against the GNDS, GNDT, DGND? 

Please share your schematic with voltage levels and part values. Please refer to the AN12605 for required external components for TPL interface.

Please download it from the MC33771B product page, under the secure files.

With Best Regards,

Jozef

[Patrick_Pavle]

Dear @JozefKozon,

AGNG, GNDS, GNDT and DGND are connected to each other at the same potential ground.

[JozefKozon]

Dear Patrick,

thank you for confirmation and for the schematic. Have you connected a BCC (Battery Cell Controller) on the other side of the bias voltage can reach up to 3.0V, but it's defined for VCC5=4.75V and the 50Ohm load. Please refer to the Table 6. in the MC33664 datasheet. From your scope, the bias voltage seems to be slightly higher, but the resolution is not best.

Could you please connect a BCC on the other side, apply VCC5=5V and please double check the RDTX+/- voltages. If the bias voltage is within the min. 2.2V to max. 3.0V boundaries, then the voltage levels are correct. 

With Best Regards,

Jozef