PIC16F877-04E/PT Microchip Technology, PIC16F877-04E/PT Datasheet - Page 478

IC MCU FLASH 8KX14 EE 44TQFP

PIC16F877-04E/PT

Manufacturer Part Number
PIC16F877-04E/PT
Description
IC MCU FLASH 8KX14 EE 44TQFP
Manufacturer
Microchip Technology
Series
PIC® 16Fr

Specifications of PIC16F877-04E/PT

Core Processor
PIC
Core Size
8-Bit
Speed
4MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
33
Program Memory Size
14KB (8K x 14)
Program Memory Type
FLASH
Eeprom Size
256 x 8
Ram Size
368 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
External
Operating Temperature
-40°C ~ 125°C
Package / Case
44-TQFP, 44-VQFP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
PIC16F87704E/PT

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
PIC16F877-04E/PT
Manufacturer:
Microchip Technology
Quantity:
10 000
PICmicro MID-RANGE MCU FAMILY
25.11
DS31025A-page 25-20
LCD Voltage Generation
Among the many ways to generate LCD voltage, two methods stand out above the crowd:
• resistor ladder
• charge pump.
The resistor ladder method, shown in
ages. This method uses inexpensive resistors to create the multi-level LCD voltages. Regardless
of the number of pixels that are energized the current remains constant. The voltage at point V3
is typically tied to V
The resistance values are determined by two factors: display quality and power consumption.
Display quality is a function of the LCD drive waveforms. Since the LCD panel is a capacitive
load, the waveform is distorted due to the charging and discharging currents. This distortion can
be reduced by decreasing the value of resistance. However, this change increases the power
consumption due to the increased current now flowing through the resistors. As the LCD panel
increases in size, the resistance value must be decreased to maintain the image quality of the
display.
Sometimes the addition of parallel capacitors to the resistance can reduce the distortion caused
by charging/discharging currents. The capacitors act as charge storage to provide current as the
display waveform transitions. In general, R is 1 k
200 k .
Figure 25-10: Resistor Ladder
Figure 25-11: Resistor Ladder with Capacitors
CC
, either internally or externally.
Figure
V
V
V
V
3
2
1
0
25-10, is most commonly used for higher V
V
V
V
V
3
2
1
0
+5V
to 50 k
R
R
R
and the potentiometer is 5 k
R
R
R
C
C
C
1997 Microchip Technology Inc.
CC
volt-
to

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