Advanced Clock Drivers Devices

Freescale Semiconductor

3

MPC9817

Figure 2. MPC9817 20-Lead SSOP Package Pinout (Top View)

MPC9817 OPERATION

Crystal Oscillator

The MPC9817 features a fully integrated Pierce oscillator

to minimize system implementation costs. Other than the

addition of a 25-MHz crystal, no external components are

required.The crystal selection should be: 25 MHz, parallel

the reference frequency may be higher than the specified

25 MHz. Externally supplied capacitors on both the XTAL_IN

and XTAL_OUT pins may be used to trim the frequency as

desired.

The crystal should be located as close to the MPC9817

XTAL_IN and XTAL_OUT pins as possible to avoid any board

level parasitic.

Power Supply Bypassing

0.01 capacitors and a minimum of one 1.0 capacitor for the

overall package. All capacitors should be located as close to

the SSOP pins as possible.

External Clock Source

An external reference source of 25 MHz may be applied to

the XTAL_IN pin. In this mode of operation, the XTAL_OUT

pin should be left floating.

XTAL_IN

XTAL_OUT

FSEL0

FSEL1

QREF2

GND

QREF1

QREF0

QA4

QA3

GND

QA2

QA1

QA0

MR/OE

GND

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

Table 3. Crystal Specifications

Parameter

Value

Crystal Cut

Fundamental AT Cut

Resonance

Parallel Resonance

5–7 pF

10 pF

Equivalent Series Resistance (ESR)

20–60

Ω