Z8F1680SH020SG Datasheet, PDF (59/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
34
5.2.1. Power-On Reset
Each device in the Z8 Encore! XP F1680 Series contains an internal Power-On Reset
(POR) circuit. The POR circuit monitors the supply voltage and holds the whole device in
the Reset state until the supply voltage reaches a safe circuit operating level when the
device is powered on.
After power on, the POR circuit keeps idle until the supply voltage drops below V_TH
voltage. Figure 7 on page 35 displays this POR timing.
After the F1680 Series MCU exits the POR state, the eZ8 CPU fetches the Reset vector.
Following this POR, the POR/VBO status bit in the Reset Status Register is set to 1.
For the POR threshold voltage (V_POR) and POR start voltage V_TH , see the Electrical
Characteristics chapter on page 349.
V_POR
V_DD = 0.0V
V_TH
V_DD = 3.3 V
Program
Execution
Internal Precision
Oscillator
Crystal
Oscillator
Internal RESET
signal
Internal POR
Reset
Oscillator
Start-up
50 ms
POR
Delay _{counter delay}
optional XTAL
counter delay
Notes
1. Not to Scale.
2. Internal Reset and POR Reset are active Low.
Figure 6. Power-On Reset Operation
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PS025015-1212
P R E L I M I N A R Y Reset, Stop Mode Recovery and Low-Voltage