The LMKDB family supports programmable output slew rate for each individual output. The slew rate can be chosen between 16 different values. There are four register field options, named SLEWRATE_OPT_#, each storing a slew rate value (chosen out of the 16 available slew rate values). A register field assignment of 0x0 is the fastest slew rate setting and a register field assignment of 0xF is the slowest slew rate setting. The SLEWRATE_OPT_# default values are found in Table 8-2. The corresponding ranges for the four default slew rates can be found in Section 6 under CLOCK OUTPUT CHARACTERISTICS - 100 MHz 85 Ω PCIe or CLOCK OUTPUT CHARACTERISTICS - 100 MHz 100 Ω PCIe for the specification Output slew rate. Slew rate is heavily dependent on trace characteristics including trace width, copper thickness, substrate height, dielectric constant, and loss tangent.

Each of these slew rates can be assigned to each output separately using the register bits SLEWRATE_SEL_CLKX_LSB and SLEWRATE_SEL_CLKX_MSB. Setting these two bits assigns the slew rate for a specific output X, as shown in Table 8-3. By default, all outputs are assigned to SLEWRATE_OPT_2.

To program the slew rate to the desired slew rate, the following sequence needs to be followed:

1. [Optional]: if the default assignments shown in Table 8-2 for each slew rate speed is not as desired, one of the slew rate options value can be changed to another slew rate.
2. Program SLEWRATE_SEL_CLKX_MSB and SLEWRATE_SEL_CLKX_LSB to assign clock output X to desired slew rate speed option, as shown in Table 8-3. The default assignments for each option can be found in Table 8-2.