tmp88fw45afg TOSHIBA Semiconductor CORPORATION, tmp88fw45afg Datasheet - Page 89

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

8. Oscillation Frequency Detector
8.1
detection frequency, or higher than an upper detection frequency. Each frequency is specified by CLKSMN and
CLKSMX register. An initial value of lower detection frequency is 8.8MHz which is a harmonics of +10% of 16MHz,
and that of upper detection frequency is 20MHz which is a maximum frequency in operating condition. For details,
refer to Figure 8-1. To change the detection frequency, CLKSMN and CLKSMX registers are used. CLKSMN and
CLKSMX can be written when the oscillation frequency detection is disabled and writing to CLKSMN/CLKSMX is
enabled by setting "F9H" to CLKSCR1. Since the oscillation frequency detection is disabled after an external reset
input, write "F9H" to CLKSCR1 and write "E4H" to CLKSCR2 register to enable its function.
become high impedance by reset. By the oscillation frequency detection reset, all I/Os except power supply pins,
RESET, XIN and XOUT become high impedance. If oscillation frequency detection reset is generated by detecting
the stopping of high frequency, the internal circuities such as registers hold the condition at the timing of oscillation
stop. To initialize these internal circuitries, an at external re-starting of oscillation is needed.
Note 1: Though the harmonics of 16MHz is 32MHz, upper detection frequency is set to 20MHz to avoid an erratic operation
Note 2: The oscillation frequency detection reset is available only in NORMAL and IDLE modes. In STOP modes, the
Configuration
The oscillation frequency detector generates a reset for I/O if the oscillation of high frequency is lower than a lower
When the TMP88FW45AFG detects the out of frequency specified CLKSMN and CLKSMX register, all I/Os
caused by exceeding 20MHz.
oscillation frequency detection reset is disabled automatically.
VDD [V]
Osc. enable
5.5
4.5
If the calculated detection frequency is lower than 8MHz or higher than 20MHz, the detection frequency
should be set within operating condition.
VDD
Figure 8-2 Oscillation Frequency Detector
Subharmonics
of 16MHz
XIN
Figure 8-1 Detection frequency range
Operating Conditions
Area
8 8.8
R
f
XOUT
R
14.4
fc [MHz]
O
16MHz
Page 75
VDD
fc
16
17.6
Oscillation
Frequency
Detector
20
Harmonics
of 16MHz-10%
Oscillation Frequency
Detection Reset
28.8
TMP88FW45AFG