PCF8813 View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
'PCF8813' PDF : 72 Pages View PDF
Philips Semiconductors
(67 + 1) × 102 pixels matrix LCD driver
Product speciï¬cation
PCF8813
17 MODULE MAKER PROGRAMMING
One Time Programmable (OTP) technology has been
implemented on the PCF8813. This enables the module
maker to program some features of the PCF8813 after it
has been assembled on an LCD module. Programming is
made under the control of the interfaces and using the
special pad VOTPPROG. This pad must be made available
on the module glass but does not need to be accessed by
the set maker.
Module maker programming is an extension of the normal
functions of the PCF8813 and is effective until specifically
instructed otherwise with the disable OTP command.
The PCF8813 features three module maker
programmable parameters:
• VLCD calibration (5 bits)
• Manufacturer identity (3 bits)
• Seal bit (1-bit).
17.1 LCD voltage calibration
Referring to Fig.47, the VLCD calibration parameter
comprises a 5-bit code (VCAL[4:0]). The code is
implemented in twos complement notation giving a
positive or negative offset to the VPR register. The range of
the VPR[6:0] register is 0 to 127. The adder in the circuit
takes this into account by having underflow and overflow
protection added to it. In the event of an overflow, the
output will be clamped to 255, and in the case of an
underflow the output will be clamped to 0.
Given that
VOP = VCAL + VPR∗
and
VLCD = a + VOP × b T(norm)
VLCD can be calculated using parameters a and b that are
defined in Table 17. An example of the relationship
between VCAL code and the VLCD calibration is shown in
Table 19, where b is assumed to be 25.6 mV.
Possible values for VCAL are given in Table 19. The default
value for VCAL when OTP is disabled is VCAL[4:0] = 00000.
handbook, full pagewidth
−16 to +15
VLCD calibration: 5-bit SIGNED value
VCAL[4:0]
VPR register: 7-bit UNSIGNED value
VPR [6:0]
0 to +127
+
VOP to high voltage
generator
MGU644
Fig.47 VLCD calibration.
2004 Mar 05
49
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