S12CPUV2 datasheet(118/138 Pages) MOTOROLA

118 / 138 page

MC9S12DT128 Device User Guide — V02.09

118

A.5.1.5 Pseudo Stop and Wait Recovery

The recovery from Pseudo STOP and Wait are essentially the same since the oscillator was not stopped in

both modes. The controller can be woken up by internal or external interrupts. After twrs the CPU starts

fetching the interrupt vector.

A.5.2 Oscillator

The device features an internal Colpitts and Pierce oscillator. The selection of Colpitts oscillator or Pierce

oscillator/external clock depends on the XCLKS signal which is sampled during reset.By asserting the

XCLKS input during reset this oscillator can be bypassed allowing the input of a square wave. Before

asserting the oscillator to the internal system clocks the quality of the oscillation is checked for each start

from either power-on, STOP or oscillator fail. tCQOUT specifies the maximum time before switching to the

internal self clock mode after POR or STOP if a proper oscillation is not detected. The quality check also

determines the minimum oscillator start-up time tUPOSC. The device also features a clock monitor. A

Clock Monitor Failure is asserted if the frequency of the incoming clock signal is below the Assert

Frequency fCMFA.

Table A-15 Oscillator Characteristics

Conditions are shown in Table A-4 unless otherwise noted

Num C

Rating

Symbol

Min

Typ

Max

Unit

C Crystal oscillator range (Colpitts)

fOSC

0.5

MHz

C Crystal oscillator range (Pierce) 1

NOTES:

1. Depending on the crystal a damping series resistor might be necessary

fOSC

0.5

MHz

P Startup Current

iOSC

100

µA

C Oscillator start-up time (Colpitts)

tUPOSC

2. fosc = 4MHz, C = 22pF.

1003

3. Maximum value is for extreme cases using high Q, low frequency crystals

D Clock Quality check time-out

tCQOUT

0.45

2.5

P Clock Monitor Failure Assert Frequency

fCMFA

100

200

KHz

6P External square wave input frequency 4

4. XCLKS =0 during reset

fEXT

0.5

MHz

D External square wave pulse width low

tEXTL

9.5

D External square wave pulse width high

tEXTH

9.5

D External square wave rise time

tEXTR

1ns

D External square wave fall time

tEXTF

1ns

D Input Capacitance (EXTAL, XTAL pins)

CIN

7pF

DC Operating Bias in Colpitts Conﬁguration on

EXTAL Pin

VDCBIAS

1.1

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