Datasheet

© 2007 Microchip Technology Inc. DS41206B-page 67
PIC16F716
FIGURE 9-7: EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 1
FIGURE 9-8: EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 2
FIGURE 9-9: EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 3
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.
VDD
33k
10k
40k
V
DD
MCLR
PIC16F716
Q1
Note 1: This brown-out circuit is less expensive, albeit
less accurate. Transistor Q1 turns off when V
DD
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.
V
DD x
R1
R1 + R2
= 0.7 V
VDD
R2
40k
V
DD
MCLR
PIC16F716
R1
Q1
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.
MCLR
PIC16F716
V
DD
VDD
Vss
RST
MCP809
VDD
bypass
capacitor