Z8F160x Zilog, Z8F160x Datasheet - Page 45

• Manufacturer Part Number: Z8F160x
• Description: Z8 Encore / Microcontrollers with Flash Memory and 10 Bit A/D Converter
• Manufacturer: Zilog

PS017610-0404
Crystal Oscillator
Internal RESET
WDT Clock
VCC = 0.0V
XOUT
signal
Power-On Reset
Voltage Brown-Out Reset
V
V
POR
VBO
The Z8F640x family products contain an internal Power-On Reset (POR) circuit. The
POR circuit monitors the supply voltage and holds the device in the Reset state until the
supply voltage reaches a safe operating level. After the supply voltage exceeds the POR
voltage threshold (V
Watch-Dog Timer oscillator. After the POR counter times out, the XTAL Counter is
enabled to count a total of 16 system clock pulses. The Z8F640x family device is held in
the Reset state until both the POR Counter and XTAL counter have timed out. After the
device exits the Power-On Reset state, the eZ8 CPU fetches the Reset vector. Following
Power-On Reset, the POR status bit in the Watch-Dog Timer Control (WDTCTL) register
is set to 1.
Figure 62 illustrates Power-On Reset operation. Refer to the Electrical Characteristics
chapter for the POR threshold voltage (V
Figure 62. Power-On Reset Operation (not to scale)
The devices in the Z8F640x family provide low Voltage Brown-Out (VBO) protection.
The VBO circuit senses when the supply voltage drops to an unsafe level (below the VBO
Oscillator
Start-up
POR
), the POR Counter is enabled and counts 514 cycles of the
counter delay
POR
Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
POR
).
counter delay
XTAL
Reset and Stop Mode Recovery
Execution
Program
Z8 Encore!
VCC = 3.3V
®
27