LC88FC2D0B Datasheet, PDF (46/47 Pages) ON Semiconductor – 16-bit Microcontroller 256K-byte Flash ROM / 24Kbyte RAM / 100-pin

VDD
Unknown-state
(POUKS)
RES#
LC88FC2D0B
(a)
(b)
POR release voltage
(PORRL)
Reset period
100μs or longer
Reset period
Figure 10 Waveform observed when only POR is used (LVD not used)
(RESET pin: Pull-up resistor R_RES only)
• The POR function generates a reset only when power is turned on starting at the VSS level.
• No stable reset will be generated if power is turned on again when the power level does not go
down to the VSS level as shown in (a). If such a case is anticipated, use the LVD function
together with the POR function or implement an external reset circuit.
• A reset is generated only when the power level goes down to the VSS level as shown in (b) and
power is turned on again after this condition continues for 100μs or longer.
VDD
LVD hysteresis width
(LVHYS)
Unknown-state
(LVUKS)
RES#
Reset period
Reset period
Reset period
LVD release voltage
(LVDET+LVHYS)
LVD reset voltage
(LVDET)
Figure 11 Waveform observed when both POR and LVD functions are used
(RESET pin: Pull-up resistor R_RES only)
• Resets are generated both when power is turned on and when the power level lowers.
• A hysteresis width (LVHYS) is provided to prevent the repetitions of reset release and entry
cycles near the detection level.
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