PCF8576DT NXP Semiconductors, PCF8576DT Datasheet - Page 9

• Manufacturer Part Number: PCF8576DT
• Manufacturer: NXP Semiconductors

Specifications of PCF8576DT

• Operating Supply Voltage (typ): 2.5/3.3/5V
• Number Of Digits: 20
• Number Of Segments: 160
• Package Type: TSSOP
• Pin Count: 56
• Mounting: Surface Mount
• Power Dissipation: 400mW
• Frequency (max): 400KHz
• Operating Supply Voltage (min): 1.8V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Supplier Unconfirmed

NXP Semiconductors
PCF8576D_9
Product data sheet
7.3 LCD voltage selector
V
The LCD voltage selector coordinates the multiplexing of the LCD in accordance with the
selected LCD drive configuration. The operation of the voltage selector is controlled by the
mode-set command (see
that apply to the preferred modes of operation, together with the biasing characteristics as
functions of V
Table 5.
A practical value for V
threshold voltage (V
the static drive mode a suitable choice is V
Multiplex drive modes of 1:3 and 1:4 with
hence the contrast ratios are smaller.
Bias is calculated by
The RMS on-state voltage (V
V
where the values for n are
The RMS off-state voltage (V
Discrimination is the ratio of V
LCD drive
mode
static
1:2 multiplex 2
1:2 multiplex 2
1:3 multiplex 3
1:4 multiplex 4
off RMS
on RMS
a = 1 for
a = 2 for
n = 1 for static mode
n = 2 for 1:2 multiplex
n = 3 for 1:3 multiplex
n = 4 for 1:4 multiplex
=
=
Discrimination ratios
1
1
V
2
3
V
LCD
LCD
Number of:
Backplanes Levels
1
bias
bias
LCD
----------------------------- -
n
----------------------------- -
n
and the resulting discrimination ratios (D), are given in
a
a
2
2
th
+
–
------------ -
1
), typically when the LCD exhibits approximately 10 % contrast. In
1
LCD
1
2a
Rev. 09 — 25 August 2009
2a
1
+
+
+
a
+
Table
a
+
is determined by equating V
a
, where the values for a are
2
3
4
4
4
n
n
2
2
on(RMS)
off(RMS)
on(RMS)
9) from the command decoder. The biasing configurations
LCD bias
configuration
static
1
1
1
1
) for the LCD is calculated with
) for the LCD is calculated with
2
3
3
3
to V
off(RMS)
1
Universal LCD driver for low multiplex rates
LCD
2
bias are possible but the discrimination and
> 3V
and is determined from
th
V
--------------------------
0
0.354
0.333
0.333
0.333
.
off RMS
V
off(RMS)
LCD
with a defined LCD
1
0.791
0.745
0.638
0.577
V
------------------------ - D
on RMS
V
LCD
PCF8576D
Equation 1
Equation
© NXP B.V. 2009. All rights reserved.
Table
Equation
2.236
2.236
1.915
1.732
=
2:
5.
--------------------------
V
V
off RMS
on RMS
3:
9 of 52
(1)
(2)