PIC16F62X
14.2.6 INTERNAL 4 MHZ OSCILLATOR
14.4
Reset
The internal RC oscillator provides a fixed 4 MHz (nom-
inal) system clock at Vdd = 5V and 25°C, see “Electrical
Specifications” section for information on variation over
voltage and temperature.
The PIC16F62X differentiates between various kinds
of reset:
a) Power-on reset (POR)
b) MCLR reset during normal operation
c) MCLR reset during SLEEP
d) WDT reset (normal operation)
e) WDT wake-up (SLEEP)
14.2.7 CLKOUT
The PIC16F62X can be configured to provide a clock
out signal by programming the configuration word. The
oscillator frequency, divided by 4 can be used for test
purposes or to synchronize other logic.
f) Brown-out Detect (BOD)
Some registers are not affected in any reset condition;
their status is unknown on POR and unchanged in any
other reset. Most other registers are reset to a “reset
state” on Power-on reset, MCLR reset, WDT reset and
MCLR reset during SLEEP. They are not affected by a
WDT wake-up, since this is viewed as the resumption
of normal operation. TO and PD bits are set or cleared
differently in different reset situations as indicated in
Table 14-4. These bits are used in software to deter-
mine the nature of the reset. See Table 14-7 for a full
description of reset states of all registers.
14.3
Special Feature: Dual Speed
Oscillator Modes
A software programmable dual speed oscillator mode
is provided when the PIC16F62X is configured in either
ER or INTRC oscillator modes. This feature allows
users to dynamically toggle the oscillator speed
between 4MHz and 37kHz. In ER mode, the 4MHz set-
ting will vary depending on the size of the external
resistor. Also in ER mode, the 37kHz operation is fixed
and does not vary with resistor size. Applications that
require low current power savings, but cannot tolerate
putting the part into sleep, may use this mode.
A simplified block diagram of the on-chip reset circuit is
shown in Figure 14-8.
The MCLR reset path has a noise filter to detect and
ignore small pulses. See Table 12-6 for pulse width
specification.
The OSCF bit in the PCON register is used to control
dual speed mode. See Section 4.2.2.6, Figure 4-9.
1999 Microchip Technology Inc.
Preliminary
DS40300B-page 99
MICROCHIP [ MICROCHIP ]
