MC13201 Technical Data, Rev. 1.1,

Freescale Semiconductor

19

Since the MC13201 contains an on-chip reference frequency trim capability, it is possible to trim out

virtually all of the initial tolerance factors and put the frequency within 0.12 ppm on a board-by-board

basis. Individual trimming of each board in a production environment allows use of the lowest cost crystal,

but requires that each board go through a trimming procedure. This step can be avoided by

using/specifying a crystal with a tighter stability tolerance, but the crystal will be slightly higher in cost.

A tolerance analysis budget may be created using all the previously stated factors. It is an engineering

judgment whether the worst case tolerance will assume that all factors will vary in the same direction or if

the various factors can be statistically rationalized using RSS (Root-Sum-Square) analysis. The aging

factor is usually specified in ppm/year and the product designer can determine how many years are to be

assumed for the product lifetime. Taking all of the factors into account, the product designer can determine

the needed specifications for the crystal and external load capacitors to meet the 802.15.4 Standard.

Figure 11. MC13201 Modem Crystal Circuit

8.2

Crystal Requirements

The suggested crystal specification for the MC13201 is shown in Table 10. A number of the stated

parameters are related to desired package, desired temperature range and use of crystal capacitive load

trimming. For more design details and suggested crystals, see application note AN3251, Reference

Oscillator Crystal Requirements for MC1319x, MC1320x, and MC1321x.

Parameter

Value

Unit

Condition

Frequency

16.000000

MHz

± 10

ppm

at 25 °C

± 15

ppm

Over desired temperature range

± 2

ppm

max

43

Ω

max

5 - 9

pF

Shunt capacitance

<2

pF

max

Mode of oscillation

fundamental

Y1

16MHz

C10

6.8pF

C11

6.8pF

Y1 = Daishinku KDS - DSX321G ZD00882

XTAL1

26

XTAL2

27

U6

MC1320x