PIC16F716
FIGURE 9-7:
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 1
FIGURE 9-9:
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 3
VDD
33k
VDD
VDD
MCP809
Vss
VDD
Q1
bypass
capacitor
10k
MCLR
VDD
40k
RST
PIC16F716
MCLR
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.
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.
FIGURE 9-8:
EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 2
VDD
R1
VDD
Q1
MCLR
R2
40k
PIC16F716
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
= 0.7 V
VDD x
R1 + R2
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
MICROCHIP [ MICROCHIP ]
