Memory Map/Register Definition
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 18-17

18.7.1 SDRAM Drive Strength Register (SDRAMDS)

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R0 0 0000000000 0 0 0 0
W
Reset0 0 0000000000 0 0 0 0
15 14 13 1211 10 9 8 7654 3 2 1 0
R0 0 0 0 0 0 SB_E SB_C SB_A SB_S SB_D
W
Reset0 0 0000111111 1 1 1 1
Reg
Addr
MBAR + 0x04

Figure 18-8. SDRAM Drive Strength Register (SDRAMDS)

Table 18-7. SDRAMDS Field Descriptions

Bits Name Description
31–10 Reserved. Should be cleared
9–8 SB_E Controls the drive strength of SDCKE. See Table 18-8 for encodings.
7–6 SB_C Controls the drive strength of SDRAM clocks. See Table 18-8 for encodings.
5–4 SB_A Controls the drive strength of SDCS[3:0], RAS, CAS, SDWE, SDADDR[12:0], and
SDBA[1:0]. See Table 18-8 for encodings.
3–2 SB_S Controls the drive strength of SDRDQS. See Table 18-8 for encodings.
1–0 SB_D Controls the drive strength of SDDATA[31:0], SDDM[3:0], and SDQS[3:0]. See
Table 18-8 for encodings.

Table 18-8. SDRAM Drive Strength Bit Encodings

SB_x[1:0] SD_VDD1
13.3V is for SDR mode, 2.5V is for DDR mode
Drive
10 3.3 8mA; SSTL_3 Class I
01 3.3 16mA; SSTL_3 Class II
00 3.3 24mA; SSTL_3
10 2.5 7.6mA; SSTL_2 Class I
01 2.5 13mA
00 2.5 15mA; SSTL_2 Class II
11 X No Drive;Hi-Z