pcf8814 NXP Semiconductors, pcf8814 Datasheet - Page 37

• Manufacturer Part Number: pcf8814
• Description: Pcf8814 65 X 96 Pixels Matrix Lcd Driver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
11.9.2
The temperature measurement is repeated every
10 seconds. The measured value is provided as a 7-bit
digital value TD[6:0] which can be read back via the
interface. The temperature can be determined from
TD[6:0] using the equation
11.9.3
Due to the temperature dependency of the liquid crystal’s
viscosity, the LCD controlling voltage V
adjusted at different temperatures to maintain optimal
contrast.
Internal temperature compensation may be enabled via
the Temperature compensation enable instruction. When
the internal temperature compensation is applied (TCE bit
is set to 1) then according to Equation (1) the V
depends also on V
component defined in Table 23), otherwise V
considered to be 0 V.
There are four temperature coefficients MA, MB, MC
and MD that correspond to four equally spaced
temperature regions (see Fig.36 and Table 22). Each
coefficient can be selected from a choice of eight different
2003 Mar 13
T
handbook, full pagewidth
65
=
1.875 TD 40
T
T
96 pixels matrix LCD driver
EMPERATURE MEASUREMENT
EMPERATURE COMPENSATION
–
T
(the temperature compensation
V LCD
C
40
Fig.36 Example of segmented temperature coefficients.
A
LCD
may have to be
10
T
is
LCD
B
(3)
20
37
slopes, or multiplication factors. Each one of these
coefficients may be independently selected by the user via
the Temperature compensation enable instruction. The
default for each slope register can be stored in OTP.
Table 22 Temperature coefficients
Notes
1. The relationship between Mn and SLOPE is derived
2. Slopes of V
SLA, SLB, SLC
C
from the ratio of an LSB for TD (1.875 K/LSB) and an
LSB for V
equations (1), (2), (3) and Table 23
and SLD
111
110
101
100
011
010
001
000
50
OP
LCD
(30 mV/LSB).
D
are calculated from
MA, MB, MC
and MD
80
2.50
1.75
1.25
1.00
0.75
0.50
0.25
0.00
T ( C)
MGW834
(1)
Objective specification
PCF8814
SLOPE
(mV/K)
40
24
20
16
12
0
8
4
(1)(2)