![](http://datasheet.mmic.net.cn/10000/CS2100P-DZZR_datasheet_1433649/CS2100P-DZZR_15.png)
CS2100-OTP
DS841F2
15
5.4.2
Ratio Modifier (R-Mod)
The Ratio Modifier is used to internally multiply/divide the currently addressed RUD (Ratio0-3 stored in the
register space remain unchanged). The available options for R-Mod are summarized in
Table 2 onpage 15. R-Mod is enabled via the M2 pin in conjunction with the appropriate setting of the M2Config[2:0]
Table 2. Ratio Modifier
5.4.3
Effective Ratio (REFF)
The Effective Ratio (REFF) is an internal calculation comprised of RUD and the appropriate modifiers, as
previously described. REFF is calculated as follows:
REFF = RUD
R-Mod
To simplify operation the device handles some of the ratio calculation functions automatically (such as
when the internal timing reference clock divider is set). For this reason, the Effective Ratio does not need
to be altered to account for internal dividers.
Ratio modifiers which would produce an overflow or truncation of REFF should not be used. In all cases,
the maximum and minimum allowable values for REFF are dictated by the frequency limits for both the
Selection of the user defined ratio from the four stored ratios is made by using the M[1:0] pins.
5.4.4
Ratio Configuration Summary
The RUD is the user defined ratio for which up to four different values (Ratio0-3) can be stored in the one
time programmable memory. The M[1:0] pins then select the user defined ratio to be used as well as the
modal configuration set. The resolution/format for the RUD is selectable. R-Mod is applied accordingly.
The user defined ratio, ratio modifier, and automatic ratio modifier make up the effective ratio REFF, the
RModSel[1:0]
R Modifier
00
0.5
01
0.25
10
0.125
11
0.0625
Referenced Control
Parameter Definition
Referenced Control
Parameter Definition