Z8F4822AR020SG Datasheet, PDF (51/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
31
Voltage Brown-Out Reset
The devices in the Z8 Encore! XP F64xx Series provide low Voltage Brown-Out protec-
tion. The VBO circuit senses when the supply voltage drops to an unsafe level (below the
VBO threshold voltage) 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 device in the Reset state.
After the supply voltage again exceeds the Power-On Reset voltage threshold, the devices
progress through a full system reset sequence, as described in the Power-On Reset section.
Following Power-On Reset, the POR status bit in the Watchdog Timer Control
(WDTCTL) Register is set to 1. Figure 9 displays Voltage Brown-Out operation. For the
VBO and POR threshold voltages (V_VBO and V_POR), see the Electrical Characteristics
chapter on page 200.
The Voltage Brown-Out circuit can be either enabled or disabled during STOP Mode.
Operation during STOP Mode is set by the VBO_AO option bit. For information about
configuring VBO_AO, see the Option Bits chapter on page 180.
V_CC = 3.3V
V_POR
V_VBO
Program
Execution
Voltage
Brown-Out
V_CC = 3.3V
Program
Execution
WDT Clock
Primary
Oscillator
Internal RESET
Signal
POR
XTAL
Counter Delay Counter Delay
Figure 9. Voltage Brown-Out Reset Operation
PS019924-0113
PRELIMINARY
Reset Sources