ZHCSVJ2I August 2007 – December 2024 CDCE937 , CDCEL937
PRODUCTION DATA
- 1
- 1 特性
- 2 應用
- 3 說明
- 4 Pin Configuration and Functions
- 5 Specifications
- 6 Parameter Measurement Information
- 7 Detailed Description
- 8 Register Maps
- 9 Application and Implementation
- 10Device and Documentation Support
- 11Revision History
- 12Mechanical, Packaging, and Orderable Information
9.2.2.2 PLL Frequency Planning
At a given input frequency (?IN), the output frequency (?OUT) of the CDCEx913 are calculated with Equation 1.
Equation 1. 
where
- M (1 to 511) and N (1 to 4095) are the multiplier/divide values of the PLL
- Pdiv (1 to 127) is the output divider
The target VCO frequency (?VCO) of each PLL is calculated with Equation 2.
Equation 2. 
The PLL internally operates as fractional divider and needs the following multiplier/divider settings:
- N
- P = 4 – int(log2N/M; if P < 0 then P = 0
- Q = int(N'/M)
- R = N′ – M × Q
where
N′ = N × 2P
N ≥ M;
80MHz ≤ ?VCO ≤ 230MHz
16 ≤ Q ≤ 63
0 ≤ P ≤ 4
0 ≤ R ≤ 51
| Example: | |||
| for ?IN = 27MHz; M = 1; N = 4; Pdiv = 2 | for ?IN = 27MHz; M = 2; N = 11; Pdiv = 2 | ||
| → | fOUT = 54MHz | → | fOUT = 74.25MHz |
| → | fVCO = 108MHz | → | fVCO = 148.50MHz |
| → | P = 4 – int(log24) = 4 – 2 = 2 | → | P = 4 – int(log25.5) = 4 – 2 = 2 |
| → | N' = 4 × 22 = 16 | → | N' = 11 × 22 = 44 |
| → | Q = int(16) = 16 | → | Q = int(22) = 22 |
| → | R = 16 – 16 = 0 | → | R = 44 – 44 = 0 |
The values for P, Q, R, and N’ are automatically calculated when using TI Pro-Clock? software.