PCF8811USLASH2DASLASH1 datasheet(69/81 Pages) NXP

69 / 81 page

PCF8811_4

Product data sheet

Rev. 04 — 27 June 2008

69 of 81

NXP Semiconductors

PCF8811

80 x 128 pixels matrix LCD driver

18. Support information

18.1 Module maker programming

One Time Programmable (OTP) technology is implemented on the PCF8811. It enables

the module maker to program some extended features of the PCF8811 after it has been

assembled on an LCD module. Programming is made under the control of the interfaces

and the use of one special pad. This pad must be made available on the module glass but

need not be accessed by the set maker.

The PCF8811 features 3 parameters programmable by the module maker:

• VLCD calibration

• Temperature coefﬁcient selection

• Seal bit

18.1.1 VLCD calibration

The ﬁrst feature included is the ability to adjust the VLCD voltage with a 5-bit code

(MMVOPCAL). This code is implemented in two’s complement notation giving rise to a

positive or negative offset to the VPR register. This is in the same manner as the on-glass

calibration pads VOS.

In theory, both may be used together but it is recommended that the VOS pads are tied to

VSS when OTP calibration is being used. This sets them to a default offset of zero. If both

are used then the addition of the two 5-bit numbers must not exceed a 5-bit result,

otherwise the resultant value is undeﬁned. The ﬁnal adder in the circuit has underﬂow and

overﬂow protection. In the event of an overﬂow, the output will be clamped to 255; during

an underﬂow the output will be clamped to 0.

The ﬁnal control to the high voltage multiplier, VOP, is the sum of all the calibration

registers and pads. The VLCD Equation 4 or Equation 5 given in Section 12.10.1 or

Section 12.10.2 must be extended to include the OTP calibration, as follows:

(7)

The possible values for MMVOPCAL[4:0] and VOS[4:0] values are given in Table 36.

Table 36.

VOS/MMVOPCAL values in two’s complement notation

Binary

Decimal

Binary

Decimal

0 0000

1 1111

−1

0 0001

1 1110

−2

0 0010

1 1101

−3

0 0011

1 1100

−4

0 0100

1 1011

−5

0 0101

1 1010

−6

0 0110

1 1001

−7

0 0111

1 1000

−8

0 1000

1 0111

−9

0 1001

1 0110

−10

LCD T

CUT

()

OS[4:0]

MMVOPCAL[4:0]

OP[7:0]

() b

PCF8811U/2DA/1 Datasheet(PDF) 69 Page - NXP Semiconductors

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