MC908QL4ME View Datasheet(PDF) - Freescale Semiconductor

Part Name

Description

Manufacturer

MC908QL4ME

M68HC08 Microcontrollers

Freescale Semiconductor 

Oscillator Characteristics

Characteristic

External RC oscillator frequency, RCCLK (1)(2)

VDD ≥ 3.0 V

VDD < 3.0 V

External clock reference frequencyy(1)(4)(5)

VDD ≥ 4.5V

VDD ≥ 3.0V

VDD < 3.0V

RC oscillator external resistor

VDD = 5 V

VDD = 3 V

Crystal frequency, XTALCLK(1)(6)(7)

ECFS1:ECFS0 = 00 ( VDD ≥ 4.5 V)

ECFS1:ECFS0 = 00 (not allowed if VDD < 3.0V)

ECFS1:ECFS0 = 01

ECFS1:ECFS0 = 10

ECFS1:ECFS0 = 00 (8)

Feedback bias resistor

Crystal load capacitance(9)

Crystal capacitors(9)

ECFS1:ECFS0 = 01(8)

Crystal series damping resistor

fOSCXCLK = 1 MHz

fOSCXCLK = 4 MHz

fOSCXCLK = 8 MHz

Feedback bias resistor

Crystal load capacitance(9)

Crystal capacitors(9)

AWU Module: Internal RC oscillator frequency

Symbol

fRCCLK

fOSCXCLK

REXT

fOSCXCLK

RB

CL

C1,C2

RS

RB

CL

C1,C2

fINTRC

Min

Typ

Max

2

—

10

2

—

8.4

dc

dc

dc

—

—

—

32

16

8.4

See Figure 17-7

See Figure 17-8

8

—

32

8

—

16

1

—

8

30

—

100

—

1

—

—

20

—

—

(2 x CL) – 5pF

—

—

20

—

—

10

—

—

0

—

—

5

—

—

18

—

—

(2 x CL) –10 pF

—

—

32

—

Unit

MHz

MHz

—

MHz

MHz

MHz

kHz

MΩ

pF

pF

kΩ

kΩ

kΩ

MΩ

pF

pF

kHz

1. Bus frequency, fOP, is oscillator frequency divided by 4.

2. Deviation values assumes trimming @25°C and midpoint of voltage range, for example 5.0 V for 5 V ± 10%,

3.3 V for 3.3 V ± 10%.

3. Values are based on characterization results, not tested in production.

4. No more than 10% duty cycle deviation from 50%.

5. When external oscillator clock is greater than 1MHz, ECFS1:ECFS0 must be 00 or 01

6. Use fundamental mode only, do not use overtone crystals or overtone ceramic resonators

7. Due to variations in electrical properties of external components such as, ESR and Load Capacitance, operation above

16 MHz is not guaranteed for all crystals or ceramic resonators. Operation above 16 MHz requires that a Negative

Resistance Margin (NRM) characterization and component optimization be performed by the crystal or ceramic resonator

vendor for every different type of crystal or ceramic resonator which will be used. This characterization and optimization

must be performed at the extremes of voltage and temperature which will be applied to the microcontroller in the

application. The NRM must meet or exceed 10x the maximum ESR of the crystal or ceramic resonator for acceptable

performance.

8. Do not use damping resistor when ECFS1:ECFS0 = 00, 10 or 11

9. Consult crystal vendor data sheet.

MC68HC908QL4 Data Sheet, Rev. 7

Freescale Semiconductor

211

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