This section describes the routing guidelines for DDR4 interface for PolarFire Family. The guidelines are with reference to maximum x72 data width from signal integrity perspective. All the guidelines are provided considering maximum data rate supported. It is recommended to evaluate the interface by performing system level signal integrity simulations. The user is assumed to have the knowledge of the memory interface guidelines.
| Clock Signals | Description |
|---|---|
| CK[1:0]_P\N | Differential Clock signals |
| Address and Command Signals | |
| A[15:0] | Address signals |
| BA[1:0] | Bank Address signals |
| BG[1:0] | Bank Group signals |
| WE | Write Enable |
| RAS_n | Row address strobe |
| CAS_n | Column address strobe |
| ACT_n | Activation Command Input |
| PAR | Command and address parity |
| Control Signals | |
| CKE | Clock Enable |
| CS_n[1:0] | Chip Select |
| ODT | On die termination |
| Reset | Reset |
| Data Group | |
| DQ[71:0] | Data signals |
| DQS[8:0]_P/N | Differential data strobe |
| M_N[8:0] | Data mask |
DDR4 interface on PolarFire supports maximum data rate of 1600 MT/s on HSIO banks. The ADDR/CMD signals are routed in fly-by topology and terminated at the last memory component with respect to VDD/2. CK signals are also routed in fly-by topology and terminated at the last memory component with respect to VDD. The data signals are routed as point to point.