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Is the 150 Ohms termination resistor for LPDDR4 clock needed?

Question asked by Raik Melzer on Apr 21, 2020
Latest reply on Apr 22, 2020 by Wigros Sun

The X-815LPD4-CPUCY is the only EVK for the i.MX8M Nano with LPDDR4 support.

In the schematics on page 5 of the SoM, there is a termination resistor with 150 Ohms (R8) placed across the clock lines DRAM_CK_T_A/DRAM_CK_C_A.

The needness of this resistor cannot be found in the CPU reference manual and also no explanation for the value of the resistor is documented in the hardware design guides.

So my question:

- is this resitor really needed (various options for clock termination can be set in the LPDDR4 memory itself, also the drive strength of the clock can be influenced in the CPU

 

Thanks for help, 

Raik

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