PIC16C925/CL Microchip Technology, PIC16C925/CL Datasheet - Page 6

• Manufacturer Part Number: PIC16C925/CL
• Description: IC MCU EPROM 4KX14 LCDDVR 68CLCC
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C925/CL

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 25
• Program Memory Size: 7KB (4K x 14)
• Program Memory Type: EPROM
• Ram Size: 176 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 68-CLCC Window, 68-CERQUAD
• For Use With: AC164308 - MODULE SKT FOR PM3 68PLCCDVA16XL680 - ADAPTER DEVICE FOR MPLAB-ICEAC164024 - ADAPTER PICSTART PLUS 68PLCCAC164022 - MODULE SKT PROMATEII 68PLCC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

PIC16C925/926
4. Module: LCD
DS80168A-page 6
The
Section 11.5.1, “CHARGE PUMP”:
The current source associated with the LCD mod-
ule charge pump has a nominal output of 10 µA
(see Figure 11-9). However, current regulation
within individual devices may vary from approxi-
mately 7 to 15 µA. Since this current sets up the
V
ate noticeable LCD contrast variations when using
the LCD charge pump.
One method to compensate for the varying current
regulation is to include a trim potentiometer in
series between the V
method is currently noted in Figure 11-9 (page 95)
of the Device Data Sheet.
To reduce the variation in the V
without using a trim potentiometer or trim resistors
(which must be manually adjusted), it is possible to
use a band gap voltage reference circuit such as
the 1.22V ZXRE1004 reference from Zetex, as
shown in Figure 2. Resistor Rx placed in series
with the band gap reference and the V
can be used to set a voltage higher than the band
gap reference voltage, if necessary. The voltage is
determined by the formula:
LCDADJ
following
voltage, variation in this current can cre-
V
LCDADJ
text
LCDADJ
= 1.22V + (I × R)
has
pin and ground. This
been
LCDADJ
added
LCDADJ
voltage,
pin
to
FIGURE 2:
As can be seen from this equation, a smaller
series resistor, R, results in smaller variations in
V
LCDADJ
V
I
DD
voltage.
V
R
ZXRE1004
10 µA
Source
(nominal)
LCDADJ
ALTERNATE METHOD FOR
REDUCING VARIATIONS IN
V
LCDADJ
 2003 Microchip Technology Inc.
VOLTAGE
Charge Pump