HMS87C1808B Datasheet, PDF (78/99 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

HMS87C1X04B/08B/16B
V_DD V_DD
D
R
R1
C
RESET
- External Power-On Reset circuit is required only if VDD
power-up is too slow. The diode D helps discharge the
capacitor quickly when VDD powers down.
- R < 40 kΩ is recommended to make sure that voltage
drop across R does not violate the device electrical specifi-
cation.
- R1 = 100Ω to 1kΩ will limit any current flowing into
RESET from external capacitor C in the event of RESET
pin breakdown due to Electrostatic Discharge (ESD) or
Electrical Overstress (EOS).
Figure 19-3 EXTERNAL POWERON RESET CIRCUIT (FOR SLOW V_DD POWER-UP)
• Address Fail Reset
The Address Fail Reset is the function to reset the system by
checking abnormal address or unwished address cauased by ex-
ternal noise, which couldn’t be returned to normal operation and
would be malfunction state. If the CPU fetch the instruction from
beyond area not in main user area address C000_H~FFFF_H, in that
case the address fail reset is occurred.
External RESET
ADDRESS FAIL RESET
WDT RESET
WDT RESETen
PFD RESET
PFD RESETen
Internal RESET
Execution
Address Fail RESET
Internal RESET
Address Fail is occurred
Figure 19-4 The opreation of Address Fail RESET
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SEP. 2004 Ver 1.03