Z8F1601 Datasheet, PDF (46/246 Pages) Zilog, Inc. – Z8 Encore Microcontrollers with Flash Memory and 10-Bit A/D Converter

Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!^®
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threshold voltage, V_VBO) and forces the device into the Reset state. While the supply volt-
age remains below the Power-On Reset voltage threshold (V_POR), the VBO block holds
the Z8F640x family device in the Reset state.
After the supply voltage again exceeds the Power-On Reset voltage threshold, the
Z8F640x family device progresses through a full System Reset sequence, as described in
the Power-On Reset section. Following Power-On Reset, the POR status bit in the Watch-
Dog Timer Control (WDTCTL) register is set to 1. Figure 63 illustrates Voltage Brown-
Out operation. Refer to the Electrical Characteristics chapter for the VBO and POR
threshold voltages (V_VBO and V_POR).
Stop mode disables the Voltage Brown-Out detector.
VCC = 3.3V
V_POR
V_VBO
Program
Execution
Voltage
Brownout
VCC = 3.3V
Program
Execution
WDT Clock
Crystal Oscillator
XOUT
Internal RESET
signal
POR
XTAL
counter delay counter delay
Figure 63. Voltage Brown-Out Reset Operation (not to scale)
Watch-Dog Timer Reset
If the device is in normal or Halt mode, the Watch-Dog Timer can initiate a System Reset
at time-out if the WDT_RES Option Bit is set to 1. This is the default (unprogrammed) set-
ting of the WDT_RES Option Bit. The WDT status bit in the WDT Control register is set to
signify that the reset was initiated by the Watch-Dog Timer.
PS017610-0404
Reset and Stop Mode Recovery