PCF8813 datasheet(49/72 Pages) PHILIPS

49 / 72 page

2004 Mar 05

Philips Semiconductors

Product speciﬁcation

(67 + 1)

× 102 pixels matrix LCD driver

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

and

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.

CAL

PR∗

LCD

T(norm)

handbook, full pagewidth

MGU644

VOP

−16 to +15

0 to

+127

to high voltage

generator

VCAL[4:0]

VPR register: 7-bit UNSIGNED value

VLCD calibration: 5-bit SIGNED value

VPR[6:0]

Fig.47 VLCD calibration.

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