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Data Sheet Uploaded 06/2017

Page 13 of 33 | Previous Page | Next Page | Table of Contents
hPPR/sPPR Support Identifier

hPPR/sPPR Support Identifier

Table 1. DDR4 Repair Mode Support Identifier

MPR Page 2 A7 A6 A5 A4 A3 A2 A1 A0
UI0 UI1 UI2 UI3 UI4 UI5 UI6 UI7
MPR0 hPPR1 sPPR2 RTT_WR Temp sensor CRC RTT_WR

Notes

  1. 0 = hPPR mode is not available, 1 = hPPR mode is available.

  2. 0 = sPPR mode is not available, 1 = sPPR mode is available.

  3. Gray shaded areas are for reference only.

Products and specifications discussed herein are subject to change by Micron without notice. This data sheet contains minimum and maximum limits specified over the power supply and temperature range set forth herein. Although considered final, these specifications are subject to change, as further product development and data characterization sometimes occur.

Excessive Row Activation

Excessive Row Activation

Rows can be accessed a limited number of times within a certain time period before adjacent rows require refresh. The maximum activate count (MAC) is the maximum number of activates that a single row can sustain within a time interval of equal to or less than the maximum activate window (tMAW) before the adjacent rows need to be refreshed, regardless of how the activates are distributed over tMAW.

Micron's DDR4 devices automatically perform a type of TRR mode in the background and provide an MPR Page 3 MPR3[3:0] of 1000, indicating there is no restriction to the number of ACTIVATE commands to a given row in a refresh period provided DRAM timing specifications are not violated.

Table 1. MAC Encoding of MPR Page 3 MPR3

[7] [6] [5] [4] [3] [2] [1] [0] MAC Comments
x x x x 0 0 0 0 Untested The device has not been tested for MAC.
x x x x 0 0 0 1 tMAC = 700K
x x x x 0 0 1 0 tMAC = 600K
x x x x 0 0 1 1 tMAC = 500K
x x x x 0 1 0 0 tMAC = 400K
x x x x 0 1 0 1 tMAC = 300K
x x x x 0 1 1 0 Reserved
x x x x 0 1 1 1 tMAC = 200K
x x x x 1 0 0 0 Unlimited There is no restriction to the number of ACTIVATE commands to a given row in a refresh period provided DRAM timing specifications are not violated.
x x x x 1 0 0 1 Reserved
x x x x : : : : Reserved
x x x x 1 1 1 1 Reserved

Note

  1. MAC encoding in MPR Page 3 MPR3.

Products and specifications discussed herein are subject to change by Micron without notice. This data sheet contains minimum and maximum limits specified over the power supply and temperature range set forth herein. Although considered final, these specifications are subject to change, as further product development and data characterization sometimes occur.

ACTIVATE Command

ACTIVATE Command

The ACTIVATE command is used to open (activate) a row in a particular bank for subsequent access. The values on the BG[1:0] inputs select the bank group, the BA[1:0] inputs select the bank within the bank group, and the address provided on inputs A[17:0] selects the row within the bank. This row remains active (open) for accesses until a PRECHARGE command is issued to that bank. A PRECHARGE command must be issued before opening a different row in the same bank. Bank-to-bank command timing for ACTIVATE commands uses two different timing parameters, depending on whether the banks are in the same or different bank group. tRRD_S (short) is used for timing between banks located in different bank groups. tRRD_L (long) is used for timing between banks located in the same bank group. Another timing restriction for consecutive ACTIVATE commands [issued at tRRD (MIN)] is tFAW (fifth activate window). Because there is a maximum of four banks in a bank group, the tFAW parameter applies across different bank groups (five ACTIVATE commands issued at tRRD_L (MIN) to the same bank group would be limited by tRC).

Figure 1. tRRD Timing

Notes

  1. tRRD_S; ACTIVATE-to-ACTIVATE command period (short); applies to consecutive ACTIVATE commands to different bank groups (that is, T0 and T4).

  2. tRRD_L; ACTIVATE-to-ACTIVATE command period (long); applies to consecutive ACTIVATE commands to the different banks in the same bank group (that is, T4 and T10).

Figure 2. tFAW Timing

Note

  1. tFAW; four activate windows.

Products and specifications discussed herein are subject to change by Micron without notice. This data sheet contains minimum and maximum limits specified over the power supply and temperature range set forth herein. Although considered final, these specifications are subject to change, as further product development and data characterization sometimes occur.