Z8F0113 datasheet(39/245 Pages) ZILOG

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PS024315-1011

P R E L I M I N A R Y

Reset Sources

Z8 Encore! XP® F0823 Series

Product Specification

Voltage Brown-Out Reset

The devices in the Z8 Encore! XP F0823 Series provide low 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 POR voltage threshold (VPOR), 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 on page 23. Following POR, the POR status bit in the Reset Status (RSTSTAT) Regis-

ter is set to 1. Figure 6 displays Voltage Brown-Out operation. For the VBO and POR

threshold voltages (VVBO and VPOR), see the Electrical Characteristics chapter on

page 196.

The VBO circuit can be either enabled or disabled during STOP Mode. Operation during

STOP Mode is set by the VBO_AO Flash Option bit. For information about configuring

VBO_AO, see the Flash Option Bits chapter on page 146.

Figure 5. Power-On Reset Operation

VCC = 0.0V

VCC = 3.3 V

VPOR

VVBO

Internal Precision

Internal RESET

signal

Program

Execution

POR

counter delay

Oscillator

Note: Not to Scale

Z8F0113 Datasheet(PDF) 39 Page - Zilog, Inc.