MC908KX2MDWE Datasheet, PDF(205/210 Page) Freescale Semiconductor, Inc – High-performance M68HC08 architecture, Fully upward-compatible object code with M6805, M146805, and M68HC05 Families

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MC908KX2MDWE Datasheet, PDF (205/210 Pages) Freescale Semiconductor, Inc – High-performance M68HC08 architecture, Fully upward-compatible object code with M6805, M146805, and M68HC05 Families

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B.4.6 Internal Oscillator Characteristics

Electrical Specifications

Characteristic(1)

Symbol

Min

Typ

Max

Unit

Internal oscillator base frequency(2), (3)

fINTOSC

230.4

320

384

kHz

Internal oscillator tolerance

fOSC_TOL

â25

+25

Internal oscillator multiplier(4)

127

1. VDD = 5.5 Vdc to 2.7 Vdc, VSS = 0 Vdc, TA = â40Â°C to +85Â°C, unless otherwise noted

2. Internal oscillator is selectable through software for a maximum frequency. Actual frequency will be multiplier (N) x base

frequency.

3. fBus = (fINTOSC / 4) x N when internal clock source selected

4. Multiplier must be chosen to limit the maximum bus frequency of 4 MHz for 2.7-V operation and 8 MHz for 4.5-V operation.

B.4.7 External Oscillator Characteristics

Characteristic(1)

Symbol

Min

Typ

Max

Unit

External clock option(2), (3)

With ICG clock disabled

With ICG clock enabled

EXTSLOW = 1(4)

EXTSLOW = 0(4)

dc(5)

32 M(6)

fEXTOSC

307.2 k

32 M(6)

External crystal options(7), (8)

EXTSLOW = 1(4)

EXTSLOW = 0(4)

fEXTOSC

30 k

100 k

Crystal load capacitance(9)

Crystal fixed capacitance(9)

2 x CL

Crystal tuning capacitance(9)

2 x CL

Feedback bias resistor(9)

Mâ¦

Series resistor (9), (10)

Mâ¦

1. VDD = 5.5 to 2.7 Vdc, VSS = 0 Vdc, TA = â40Â°C to +85Â°C, unless otherwise noted

2. Setting EXTCLKEN configuration option enables OSC1 pin for external clock square-wave input.

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

4. EXTSLOW configuration option configures external oscillator for a slow speed crystal and sets the clock monitor circuits

of the ICG module to expect an external clock frequency that is higher/lower than the internal oscillator base frequency,

fINTOSC.

5. Some modules may require a minimum frequency greater than dc for proper operation. See appropriate table for this

information.

6. MCU speed derates from 32 MHz at VDD = 4.5 Vdc to 16 MHz at VDD = 2.7 Vdc.

7. Setting EXTCLKEN and EXTXTALEN configuration options enables OSC1 and OSC2 pins for external crystal option.

8. fBus = (fEXTOSC / 4) when external clock source is selected.

9. Consult crystal vendor data sheet, see Figure 7-3. External Clock Generator Block Diagram.

10. Not required for high-frequency crystals

MC68HC908KX8 â¢ MC68HC908KX2 â¢ MC68HC08KX8 Data Sheet, Rev. 2.1

Freescale Semiconductor

205

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