IC80LV52 Datasheet, PDF (8/22 Pages) Integrated Circuit Solution Inc – CMOS SINGLE CHIP LOW VOLTAGE 8-BIT MICROCONTROLLER

IC80LV52
IC80LV32
Power-on Reset
An automatic reset can be obtained when VCC goes
through a 10µF capacitor and GND through an 8.2K
resistor, providing the VCC rise time does not exceed
1 msec and the oscillator start-up time does not exceed
10 msec. This power-on reset circuit is shown in Figure 5.
The CMOS devices do not require the 8.2K pulldown
resistor, although its presence does no harm.
When power is turned on, the circuit holds the RST pin high
for an amount of time that depends on the value of the
capacitor and the rate at which it charges. To ensure a
good reset, the RST pin must be high long enough to allow
the oscillator time to start-up (normally a few msec) plus
two machine cycles.
Note that the port pins will be in a random state until the
oscillator has start and the internal reset algorithm has
written 1s to them.
With this circuit, reducing VCC quickly to 0 causes the RST
pin voltage to momentarily fall below 0V. However, this
voltage is internally limited, and will not harm the device.
Vcc
+
10 F
-
8.2K Ω
Vcc
IC80LV52/32
RST
GND
Figure 5. Power-On Reset Circuit
12 OSC. PERIODS
S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4
RST
SAMPLE
RST
SAMPLE
RST
INTERNAL RESET SIGNAL
ALE
PSEN
P0
INST ADDR INST ADDR INST ADDR INST ADDR INST ADDR
11 OSC. PERIODS
19 OSC. PERIODS
Figure 6. Reset Timing
8
Integrated Circuit Solution Inc.
MC006-0B