PCF8579T NXP Semiconductors, PCF8579T Datasheet - Page 8

• Manufacturer Part Number: PCF8579T
• Manufacturer: NXP Semiconductors

Specifications of PCF8579T

• Operating Supply Voltage (typ): 3.3/5V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Package Type: VSO
• Pin Count: 56
• Mounting: Surface Mount
• Power Dissipation: 400mW
• Operating Supply Voltage (min): 2.5V
• Operating Supply Voltage (max): 6V
• Lead Free Status / Rohs Status: Not Compliant

NXP Semiconductors
PCF8579_5
Product data sheet
8.2 Multiplexed LCD bias generation
V
V
Remark: Do not transfer data on the I
reset action to complete.
The bias levels required to produce maximum contrast depend on the multiplex rate and
the LCD threshold voltage (V
LCD exhibits 10 % contrast.
the discrimination ratios (D) for the different multiplex rates as functions of V
The RMS on-state voltage (V
and the RMS off-state voltage (V
where the values for n are determined by the multiplex rate (1:n). Valid values for n are:
Table 4.
V
Bias ratios
------------- -
V
------------- -
V
------------- -
V
------------- -
V
oper
off RMS
on RMS
n = 8 for 1:8 multiplex
n = 16 for 1:16 multiplex
n = 24 for 1:24 multiplex
n = 32 for 1:32 multiplex
V
V
V
V
oper
oper
oper
oper
2
3
4
5
=
V
=
=
DD
Optimum LCD voltages
V
V
–
oper
oper
V
LCD
1
-- -
n
------------------------------ -
Multiplex rate
1:8
0.739
0.522
0.478
0.261
2
+
n
------------------------
n
n 1
n
Rev. 05 — 11 May 2009
n 1
–
+
n
–
+
1
1
Table 4
2
th
on(RMS)
). V
off(RMS)
th
LCD column driver for dot matrix graphic displays
is typically defined as the RMS voltage at which the
) for the LCD is calculated with the equation
1:16
0.800
0.600
0.400
0.200
shows the optimum voltage bias levels and
2
C-bus for at least 1 ms after power-on to allow the
) with the equation
1:24
0.830
0.661
0.339
0.170
PCF8579
© NXP B.V. 2009. All rights reserved.
1:32
0.850
0.700
0.300
0.150
oper
.
Table 5
8 of 41
(1)
(2)
(3)