PIC18F86K90-I/PT Microchip Technology, PIC18F86K90-I/PT Datasheet - Page 190

• Manufacturer Part Number: PIC18F86K90-I/PT
• Description: 64kB Flash, 4kB RAM, 1kB EE, 16MIPS, NanoWatt XLP, LCD, 5V 80 TQFP 12x12x1mm TRA
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 18Fr

Specifications of PIC18F86K90-I/PT

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 64MHz
• Connectivity: I²C, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 24x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TQFP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F87K90 FAMILY
13.5.1
The SOSC oscillator is also available as a clock source
in power-managed modes. By setting the clock select
bits, SCS<1:0> (OSCCON<1:0>), to ‘01’, the device
switches to SEC_RUN mode and both the CPU and
peripherals are clocked from the SOSC oscillator. If the
IDLEN bit (OSCCON<7>) are cleared and a SLEEP
instruction is executed, the device enters SEC_IDLE
mode. Additional details are available in Section 4.0
“Power-Managed Modes”.
Whenever the SOSC oscillator is providing the clock
source, the SOSC System Clock Status Flag,
SOSCRUN (OSCCON2<6>), is set. This can be used
to determine the controller’s current clocking mode. It
can also indicate the clock source currently being used
by the Fail-Safe Clock Monitor.
If the Clock Monitor is enabled and the SOSC oscillator
fails while providing the clock, polling the SOCSRUN
bit will indicate whether the clock is being provided by
the SOSC oscillator or another source.
13.5.2
The SOSC oscillator circuit draws very little power
during operation. Due to the low-power nature of the
oscillator, it may also be sensitive to rapidly changing
signals in close proximity. This is especially true when
the oscillator is configured for extremely low-power
mode (CONFIG1L<4:3> (SOSCSEL) = 01).
The oscillator circuit, displayed in Figure 13-2, should
be located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than V
If a high-speed circuit must be located near the oscillator,
it may help to have a grounded guard ring around the
oscillator circuit. The guard, as displayed in Figure 13-3,
could be used on a single-sided PCB or in addition to a
ground plane. (Examples of a high-speed circuit include
the ECCP1 pin, in Output Compare or PWM mode, or
the primary oscillator, using the OSC2 pin.)
DS39957B-page 190
USING SOSC AS A
CLOCK SOURCE
SOSC OSCILLATOR LAYOUT
CONSIDERATIONS
SS
or V
DD
.
Preliminary
FIGURE 13-3:
In the Low Drive Level mode, SOSCSEL<1:0> = 01, it
is critical that RC2 I/O pin signals be kept away from the
oscillator circuit. Configuring RC2 as a digital output,
and toggling it, can potentially disturb the oscillator cir-
cuit, even with a relatively good PCB layout. If possible,
either leave RC2 unused or use it as an input pin with
a slew rate limited signal source. If RC2 must be used
as a digital output, it may be necessary to use the High
Drive Level Oscillator mode (SOSCSEL<1:0> = 11)
with many PCB layouts.
Even in the High Drive Level mode, careful layout
procedures should still be followed when designing the
oscillator circuit.
In addition to dV/dt induced noise considerations, it is
important to ensure that the circuit board is clean. Even
a very small amount of conductive soldering flux
residue can cause PCB leakage currents that can
overwhelm the oscillator circuit.
13.6
The TMR1 register pair (TMR1H:TMR1L) increments
from 0000h to FFFFh and rolls over to 0000h. The
Timer1 interrupt, if enabled, is generated on overflow
which is latched in interrupt flag bit, TMR1IF
(PIR1<0>). This interrupt can be enabled or disabled
by setting or clearing the Timer1 Interrupt Enable bit,
TMR1IE (PIE1<0>).
Note: Not drawn to scale.
Timer1 Interrupt
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
 2010 Microchip Technology Inc.
OSC1
RC0
V
V
OSC2
RC1
RC2
DD
SS