Z8F082ASH020SC datasheet(40/244 Pages) ZILOG

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PS024705-0405

P R E L I M I N A R Y

Reset and STOP Mode Recovery

Z8 Encore! XP® F08xA Series

Product Specification

Figure 4.Power-On Reset Operation

Voltage Brown-Out Reset

The devices in the Z8 Encore! XP® F08xA 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 (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. Following Power-On Reset, the POR status bit in the Reset Status (RSTSTAT) regis-

ter is set to 1. Figure 5 illustrates Voltage Brown-Out operation. Refer to the chapter

“Electrical Characteristics” on page 191 for the VBO and POR threshold voltages (VVBO

and VPOR).

The Voltage Brown-Out circuit can be either enabled or disabled during STOP mode.

Operation during STOP mode is set by the VBO_AO Flash Option Bit. Refer to the Flash

Option Bits chapter for information about configuring VBO_AO.

VCC = 0.0V

VCC = 3.3V

VPOR

VVBO

Internal Precision

Internal RESET

signal

Program

Execution

Oscillator

Start-up

POR

counter delay

optional XTAL

counter delay

Oscillator

Crystal

Oscillator

Note: Not to Scale

Z8F082ASH020SC Datasheet(PDF) 40 Page - Zilog, Inc.