PIC16F716-I-P Datasheet, PDF (69/136 Pages) Microchip Technology – 8-bit Flash-based Microcontroller with A/D Converter and Enhanced Capture/Compare/PWM

FIGURE 9-7:
VDD
33k
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 1
VDD
Q1
10k
MCLR
40k _PIC16F716
Note 1: 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.
FIGURE 9-8:
VDD
R1
R2
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 2
VDD
Q1
MCLR
40k _PIC16F716
PIC16F716
FIGURE 9-9:
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 3
VDD
MCP809 _bypass
Vss
capacitor
VDD
RST
VDD
MCLR
PIC16F716
Note 1:
This brown-out protection circuit employs
Microchip Technology’s MCP809
microcontroller supervisor. The MCP8XX and
MCP1XX families of supervisors provide
push-pull and open collector outputs with
both high and low active Reset pins. There
are 7 different trip point selections to
accommodate 5V and 3V systems.
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:
R1
VDD x _{R1 + R2} ^{= 0.7 V}
2: Internal Brown-out Reset should be disabled
when using this circuit.
3: Resistors should be adjusted for the
characteristics of the transistor.
© 2007 Microchip Technology Inc.
DS41206B-page 67