PIC16F-ESLASHML datasheet(108/178 Pages) MICROCHIP

108 / 178 page

PIC16F627A/628A/648A

DS40044F-page 106

FIGURE 14-11:

EXTERNAL POWER-ON

RESET CIRCUIT (FOR

SLOW VDD POWER-UP)

FIGURE 14-12:

EXTERNAL BROWN-OUT

PROTECTION CIRCUIT 1

FIGURE 14-13:

EXTERNAL BROWN-OUT

PROTECTION CIRCUIT 2

Note

External Power-on Reset circuit is required

only if VDD power-up slope is too slow. The

diode D helps discharge the capacitor

quickly when VDD powers down.

R < 40 k

Ω is recommended to make sure

that voltage drop across R does not violate

the device’s electrical specification.

R1 = 100

Ω to 1 kΩ will limit any current

flowing into MCLR from external capacitor

C in the event of MCLR/VPP pin break-

down due to Electrostatic Discharge (ESD)

or Electrical Overstress (EOS).

VDD

MCLR

PIC16F627A/628A/648A

VDD

Note

This circuit will activate Reset when VDD

goes below (Vz + 0.7V) where Vz = Zener

voltage.

2: Internal Brown-out Reset circuitry should

be disabled when using this circuit.

VDD

33k

10k

40k

VDD

MCLR

PIC16F627A/628A/648A

R1 + R2

= 0.7 V

VDD

40k

VDD

MCLR

PIC16F627A/628A/648A

Note

1: This brown-out circuit is less expensive,

albeit less accurate. Transistor Q1 turns off

when VDD is below a certain level such that:

2: Internal Brown-out Reset should be

disabled when using this circuit.

3: Resistors should be adjusted for the

characteristics of the transistor.

VDD x

R1 + R2

= 0.7 V

PIC16F-E/ML 数据表(PDF) 108 Page - Microchip Technology

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PIC16F-E/ML 数据表(PDF) 108 Page - Microchip Technology

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