PIC18LF4539T-I/PT Microchip Technology, PIC18LF4539T-I/PT Datasheet - Page 3

• Manufacturer Part Number: PIC18LF4539T-I/PT
• Description: IC MCU FLASH 12KX16 EE AD 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18LF4539T-I/PT

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 24KB (12K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 1408 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Processor Series: PIC18LF
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 1408 B
• Interface Type: I2C, SPI, AUSART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 16 bit
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: DV164005, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1. Module: Timer1 (Asynchronous Counter)
TABLE 1:
© 2007 Microchip Technology Inc.
When writing to the TMR1H register, under
specific conditions, it is possible that the TMR1L
register will miss a count while connected to the
external oscillator via the T1OSO and T1OSI pins.
When Timer1 is started, the circuitry looks for a
falling edge before a rising edge can increment the
counter. Writing to the TMR1H register is similar to
starting Timer1; therefore, the former logic stated
Work around
Operating Conditions: F
from Sleep, Timer1 interrupt enabled, global
interrupts enabled.
The code excerpts in Example 1, Example 2 and
Example 3 show how the TMR1H register can be
updated while the external clock (32.768 kHz) is
still on its high pulse.
40 MHz (PIC18)
16 MHz
20 MHz
FREQUENCY DEPENDENT INSTRUCTION EXECUTION AMOUNTS
1 MHz
2 MHz
4 MHz
8 MHz
F
OSC
OSC
≥ 4 MHz, no wake-ups
T
CY
0.25
0.5
0.2
0.1
4
2
1
(μs)
applies any time the TMR1H register is written. If
the TMR1H register is not completely written to
during the high pulse of the external clock, then the
TMR1L register will miss a count due to the circuit
operation stated previously. The high pulse of a
32.768 kHz external clock crystal yields a 15.25 μs
window for the write to TMR1H to occur. The
amount of instructions that can be executed within
this window is frequency dependent, as shown in
Table 1 below.
The importance of the code examples is that the
bold instructions are executed within the first
15.25 μs high pulse on the external clock after the
Timer1 overflow occurred. This will allow the
TMR1L register to increment correctly.
TIMER1 MODULE
T
CY
within 15.25 μs
15.25
76.25
152.5
3.81
7.63
30.5
61
DS80233C-page 3