73M1903C-EVM Maxim Integrated Products, 73M1903C-EVM Datasheet - Page 19

• Manufacturer Part Number: 73M1903C-EVM
• Description: BOARD DEMO 73M1903C WORLDWIDE
• Manufacturer: Maxim Integrated Products

Specifications of 73M1903C-EVM

• Main Purpose: Interface, Analog Front End (AFE)
• Utilized Ic / Part: *
• Primary Attributes: *
• Secondary Attributes: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Embedded: -

DS_1903C_033
6 Clock Generation
6.1
The crystal oscillator operates over wide choice of crystals (from 4.9 MHz to 27 MHz) and it is first input to
a Numerically Controlled Oscillator (NCO) -based prescaler (divider) prior to being passed onto an
on-chip PLL. The intent of the prescaler is to convert the crystal oscillator frequency, Fxtal, to a
convenient frequency to be used as a reference frequency, Fref, for the PLL. The NCO prescaler
requires a set of three numbers to be entered through the serial port (Pseq[7:0], Prst[2:0] and Pdvsr[2:0].
The PLL also requires 3 numbers as for programming; Ndvsr[6:0], Nseq[7:0], and Nrst[2:0]. The following
is a brief description of the registers that control the NCOs, PLLs, and sample rates for the 73M1903C IC.
The tables show some examples of the register settings for different clock and sample rates. A more
detailed discussion on how these values are derived can be found in Appendix B.
Rev. 5.0
Crystal Oscillator and Prescaler NCO
2.4*10/7*3 = 10.2857142857
2.4*10/7*4 = 13.7142857143
2.4*8/7*4 = 10.9714285714*
2.4*8/7*3 = 8.22857142858
Table 5: Clock Generation Register Settings for Fxtal = 27 MHz
FXtal
Reg Address
Fs(kHz)
prescaler
11.2*
12.8*
12.0
14.4
16.0
7.2
8.0
8.4
9.0
9.6
NCO
Fref
Figure 6: Clock Generation
Ichp Control
LockDet
PFD
Dn
Up
Kd
DA EF 20 13 10 C4
DA EF 31 15 04 C2
DA EF 31 16 14 C4
DA EF 31 18 XX C0
DA EF 32 19 1A C4
DA EF 43 1B 54 C6
DA EF 24 20 XX C0
DA EF 46 26 14 C4
A4 E9 17 19 1A C4
8h 9h Ah Bh Ch Dh*
80 F5 41 1D 06 C2
40 C7 23 0D A4 C7
54 C7 23 0E 10 C4
80 E8 15 11 0E C3
54 CB 26 1A 0E C3
3
Charge
Pump
NCO
Kvco Control
C1
R1
C2
3
Kvco
VCO
(μA)
Ichp
10
12
10
10
10
12
12
8
8
8
8
6
8
6
73M1903C Data Sheet
Divide
by 2/1
FrcVco
Kvco
[2:0]
0
1
1
1
1
2
3
3
3
4
5
6
6
7
0
1
System
Clock
19