FIGURE 13-14: EXTERNAL POWER-ON
RESET CIRCUIT (FOR SLOW
VDD POWER-UP)
VDD
D
R
C
R1
MCLR
PIC16CXX
Note 1: 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.
2: R < 40 kΩ is recommended to make sure
that voltage drop across R does not violate
the devices electrical specifications.
3: R1 = 100Ω 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 Electrostatic Overstress (EOS).
PIC16C6X
FIGURE 13-15: EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 1
VDD
33k
VDD
10k
MCLR
40k PIC16CXX
Note 1: This circuit will activate reset when VDD
goes below (Vz + 0.7V) where Vz = Zener
voltage.
2: Internal brown-out detection on the
PIC16C62A/R62/63/R63/64A/R64/65A/
R65/66/67 should be disabled when using
this circuit.
3: Resistors should be adjusted for the
characteristics of the transistors.
FIGURE 13-16: EXTERNAL BROWN-OUT
PROTECTION CIRCUIT 2
VDD
R1
R2
VDD
Q1
MCLR
40k PIC16CXX
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:
VDD •
R1 = 0.7V
R1 + R2
2: Internal brown-out detection on the
PIC16C62A/R62/63/R63/64A/R64/65A/
R65/66/67 should be disabled when using
this circuit.
3: Resistors should be adjusted for the
characteristics of the transistors.
© 1997 Microchip Technology Inc.
DS30234D-page 135