SN8P2613 datasheet(45/102 Pages) SONIX

45 / 102 page

SN8P2610 Series

8-Bit Micro-Controller

SONiX TECHNOLOGY CO., LTD

Page 45

Version 1.3

3.6.4 Voltage Bias Reset Circuit

MCU

VDD

VSS

VCC

GND

RST

47K ohm

2K ohm

10K ohm

The voltage bias reset circuit is a low cost voltage detector and can improve brown out reset condition completely.

The operating voltage is not accurate as zener diode reset circuit. Use R1, R2 bias voltage to be the active level. When

VDD voltage level is above or equal to “0.7V x (R1 + R2) / R1”, the C terminal of the PNP transistor outputs high

voltage and MCU operates normally. When VDD is below “0.7V x (R1 + R2) / R1”, the C terminal of the PNP transistor

outputs low voltage and MCU is in reset mode.

Decide the reset detect voltage by R1, R2 resistances. Select the right R1, R2 value to conform the application. In the

circuit diagram condition, the MCU’s reset pin level varies with VDD voltage variation, and the differential voltage is

0.7V. If the VDD drops and the voltage lower than reset pin detect level, the system would be reset. If want to make the

reset active earlier, set the R2 > R1 and the cap between VDD and C terminal voltage is larger than 0.7V. The external

reset circuit is with a stable current through R1 and R2. For power consumption issue application, e.g. DC power

system, the current must be considered to whole system power consumption.

Note: Under unstable power condition as brown out reset, “Zener diode rest circuit” and “Voltage bias

reset circuit” can protects system no any error occurrence as power dropping. When power drops

below the reset detect voltage, the system reset would be triggered, and then system executes

reset sequence. That makes sure the system work well under unstable power situation.

SN8P2613 Datasheet(PDF) 45 Page - SONiX Technology Company