Z8F042ASJ020EG2156 Datasheet, PDF (41/280 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F082A Series
Product Specification
25
V_POR
V_VBO
V_CC = 0.0 V
V_CC = 3.3V
Program
Execution
Internal Precision
Oscillator
Crystal
Oscillator
Internal RESET
signal
Oscillator
Start-up
Note: Not to Scale
POR
counter delay
optional XTAL
counter delay
Figure 5. Power-On Reset Operation
Voltage Brown-Out Reset
The devices in the Z8 Encore! XP F082A Series provide low Voltage Brown-Out (VBO)
protection. 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 voltage remains below the Power-On Reset voltage threshold (V_POR), the VBO
block holds the device in the Reset.
After the supply voltage again exceeds the Power-On Reset voltage threshold, the device
progresses through a full System Reset sequence, as described in the Power-On Reset sec-
tion. Following Power-On Reset, the POR status bit in the Reset Status (RSTSTAT) Regis-
ter is set to 1. Figure 6 displays Voltage Brown-Out operation. See the Electrical
Characteristics chapter on page 226 for the VBO and POR threshold voltages (V_VBO and
V_POR).
The Voltage Brown-Out circuit can be either enabled or disabled during Stop Mode. Oper-
ation during Stop Mode is set by the VBO_AO Flash option bit. See the Flash Option Bits
chapter on page 159 for information about configuring VBO_AO.
PS022828-0413
PRELIMINARY
Reset Sources