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MEC1404 Datasheet, PDF (507/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC
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MEC140X/1X
TABLE 43-5: CLOCK TIMING PARAMETERS
Clock
48 MHz Ring
Oscillator
SUSCLK
32kHz_INT_
OSC
Parameters
Start-up accuracy (without 32 kHz
present)
Start-up delay from 0 MHz to Start-
up accuracy
Operating Frequency (with exter-
nal 32kHz clock source present
after frequency lock to 48 MHz)
Operating Frequency (with inter-
nal 32 kHz oscillator present after
frequency lock to 48 MHz)
Note 43-3
Adjustment Delay from Start-up
accuracy to Operating accuracy
(time to attain frequency lock - with
32 kHz present)
Adjustment Delay when resuming
from Heavy Sleep 3 and System
Deepest Sleep state.
(time to re-attain frequency lock -
with external 32 kHz present)
Operating Frequency (with exter-
nal 32 kHz removed after fre-
quency locked to 48 MHz)
Operating Frequency
Period
High Time
Low Time
Fall Time
Rise Time
Operating Frequency
Start-up delay from 0k Hz to Oper-
ating Frequency
Symbol
fSU
tSU
fOP
fOP
tADJ
tADJ
fOP
-
-
-
-
-
-
-
-
MIN
22
-
47.04
TYP
-
-
48
MAX
53
6
48.95
46.08
48
49.92
0.03
-
4
(Note 43-3)
-
0.60
1
(Note 43-3)
43.2
-
52.8
(Note 43-5)
(Note 43-5)
-
(Note 43-4)
10
10
-
-
32.112
150
32.768
30.52
-
-
32.768
-
(Note 43-4)
1
1
33.424
Units
MHz
µs
MHz
MHz
ms
ms
MHz
kHz
µs
us
us
us
us
kHz
us
Note 43-2
Note 43-3
Note 43-4
Note 43-5
Without the external clock, the 48MHz clock will vary up to +/-4% which may affect the timing
parameters of certain blocks. In particular it may not be accurate enough to ensure that the UART
will work, depending on the accuracy of the clock of the external device.
This time applies if the external 32KHz clock input is available or if the Internal Oscillator clock source
is enabled via the Clock Enable Register on page 444.
SUSCLK is required to have an accuracy of +/- 100 ppm.
The drift in frequency after frequency lock if the 32kHz clock is removed is determined by varying
temperature while voltage is held constant.
 2015 - 2016 Microchip Technology Inc.
DS00001956D-page 507
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