DAC39RFS10 datasheet(74/177 Pages) TI2

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7.4.2 JESD204C Interface Modes

Each operational mode has a limited set of available interface formats (number of lanes, resolution).

7.4.2.1 JESD204C Interface Modes

The device JESD204C modes are configured with the parameters defined in Table 7-19, Table 7-20 and Table

7-21.

Table 7-19. JESD204C Interface Parameter Definitions

Parameter

Description

JMODE

JESD204C mode number. The user configures this parameter to choose a supported mode. Most other parameters

are derived from this setting. See Table 7-22.

Lanes per sample stream. This is derived from JMODE. See Table 7-22.

Ratio of clock to input sample rate. LT = FCLK / FINPUT. Not that DES2X mode does not affect the value of LT.

Interpolation factor 1-256x is programmed in the DUC_L register.

Maximum number of lanes used for a given JMODE. The link scales down the number of active lanes (L) depending

on how many channels are enabled. See JESD_M register.

Maximum number of streams for a given JMODE. Mx is computed automatically according to Table 7-22. The user

can specify the actual number of streams (M) using the JESD_M register.

Number of bits transmitted per lane per CLK cycle. Derived from JMODE and LT (see )Table 7-22. Based on R, the

user must program REFDIV, MPY, and RATE registers. Additionally, the maximum CLK frequency is a function of R.

Sample Interleaving/Increment Factor. A value of 1 indicates that the standard transport layer mapping from the

JESD204C standard is used (samples are mapped linearly from 0 to S-1). A value greater than 1 indicates that an

alternate mapping is used as follows: Map samples starting with sample 0, incrementing the index by SI. Repeat this

as many times as necessary to map all S samples, starting each repetition at an index that is one larger than the

previous repetition. See JESD Format Diagrams JESD Format Diagrams.

For 8b/10b operation, KR defines the legal values of K (frames per multiframe). The legal values are restricted

to facilitate upset immunity of the elastic buffer. The multiframe length is restricted to a multiple of the elastic

buffer depth of 64 characters (buffer depth is reduced to 32 characters if K=32 and F=1). For 8b/10b modes, K is

programmed via the KM1 register.

DDS39RF12, DDS39RFS12

SBASB21 – SEPTEMBER 2024

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