PIC16F1939-I/PT Microchip Technology Inc., PIC16F1939-I/PT Datasheet - Page 336

• Manufacturer Part Number: PIC16F1939-I/PT
• Description: 44 TQFP 10x10x1mm TRAY, 28KB Flash, 1KB RAM, 256B EEPROM, LCD, 1.8-5.5V
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F1939-I/PT

• A/d Inputs: 14-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 8 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 36
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin TQFP
• Programmable Memory: 28K Bytes
• Ram Size: 1K Bytes
• Speed: 32 MHz
• Temperature Range: –40 to 125 °C
• Timers: 4-8-bit, 1-16-bit
• Voltage, Range: 1.8-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16F193X/LF193X
26.4
The internal reference ladder can be used to divide the
LCD bias voltage two or three equally spaced voltages
that will be supplied to the LCD segment pins. To create
this, the reference ladder consists of three matched
resistors. Refer to Figure 26-3.
26.4.1
When in 1/2 Bias mode (BIASMD = 1), then the middle
resistor of the ladder is shorted out so that only two
voltages are generated. The current consumption of the
ladder is higher in this mode, with the one resistor
removed.
TABLE 26-3:
DS41364D-page 336
Low
Medium
High
Power
Mode
LCD Bias Internal Reference
Ladder
BIAS MODE INTERACTION
Nominal Resistance of
LCD INTERNAL LADDER
POWER MODES (1/3 BIAS)
Entire Ladder
300 kohm
30 kohm
3 Mohm
Nominal
100 µA
10 µA
1 µA
I
DD
Preliminary
26.4.2
The internal reference ladder may be operated in one of
three power modes. This allows the user to trade off LCD
contrast for power in the specific application. The larger
the LCD glass, the more capacitance is present on a
physical LCD segment, requiring more current to
maintain the same contrast level.
Three different power modes are available, LP, MP and
HP. The internal reference ladder can also be turned off
for applications that wish to provide an external ladder
or to minimize power consumption. Disabling the
internal reference ladder results in all of the ladders
being disconnected, allowing external voltages to be
supplied.
Whenever the LCD module is inactive (LCDA = 0), the
internal reference ladder will be turned off.
POWER MODES
 2009 Microchip Technology Inc.