tmp88fw45afg TOSHIBA Semiconductor CORPORATION, tmp88fw45afg Datasheet - Page 92

• Manufacturer Part Number: tmp88fw45afg
• Description: 8 Bit Microcontroller Tlcs-870/x Series
• Manufacturer: TOSHIBA Semiconductor CORPORATION

8.3
Function
8.3.2
8.3.3
while the oscillation frequency detection circuit is enabled or writing is disabled by setting "06H" to CLKSCR1.
Therefore, to change the detection frequency, disable the oscillation frequency detection by setting "00H" to
CLKSCR2 with CLKSCR1="F9H". The detection frequency is calculated by the formula shown below.
CLKSMX is 40H which is set to 20MHz. The detection frequency should be set within the operation condition
which is from 8MHz to 20MHz.
detection reset, and the values are held. To initialize these registers, set the RESET pin (external factor reset) to
the low level.
CLKSMX, the oscillation frequency detector outputs a reset signal for all I/Os.
frequency detection reset is released.
Setting the Lower and Higher Frequency for Detection
Oscillation Frequency Detection Reset
Note 1: After writing data to CLKSMN and CLKSMX, set "06H" to CLKSCR1 to protect CLKSMN and CLKSMX.
Note 2: Specify an appropriate value to CLKSMN and CLKSMX depending on the clock frequency to be used under
Note 1: A denominator of formula will be determined after evaluation.
The detection frequency is controlled by CLKSMN and CLKSMX registers. These registers can not be written
In the TMP88FW45AFG, the initial value of CLKSMN is 20H which is set to 8.8MHz and the initial value of
CLKSMN and CLKSMX are not initialized with an internal factor reset including the oscillation frequency
If the TMP88FW45AFG detects lower frequency specified by CLKSMN or higher frequency specified by
When the oscillation resumes its normal frequency and continues for some period (T
a. When the high frequency oscillation becomes abnormal
b. When the high frequency oscillation stops
the condition of CLKSMN<CLKSMX
oscillation frequency detection reset is generated. By oscillation frequency detection reset initilizes all
I/Os except power supply pins, RESET, XIN and XOUT become high impedance.
tion reset is generated. By oscillation frequency detection reset initilizes all I/Os except power supply
pins, RESET, XIN and XOUT become high impedance. However, since the internal circuitries such
as CPU are initilized by a reset signal latched by high frequency, the internal circuitries hold the state
at the oscillation frequency detection.
When an abnormal (lower or higher) frequency oscillation continues for some period (T
When the high frequency oscillation stops for some period (T
CLKSMN value =
CLKSMX value =
Lower Detection Frequency [MHz]
Upper Detection Frequency [MHz]
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0.275
0.312
(rounding down the fraction)
(rounding up the fraction)
OFD
), the oscillation frequency detec-
TMP88FW45AFG
OFD
), the oscillation
OFD
), the