PCF8535 datasheet(11/52 Pages) PHILIPS

11 / 52 page

1999 Aug 24

Philips Semiconductors

Objective speciﬁcation

× 133 pixel matrix driver

PCF8535

7.9

Set multiplex rate

The PCF8535 can be used to drive displays of varying sizes. The multiplex mode selected controls which rows are used.

In all cases, the last row is always driven and is intended for icons. If Top Row Swap (TRS) is at logic 1 then the icon row

will be output on pad R48. M[2:0] selects the multiplex rate (see Table 2).

Table 2

Multiplex rates

7.10

Bias system

7.10.1

SET BIAS SYSTEM

The bias voltage levels are set in the ratio of R

− R − nR − R − R. Different multiplex rates require different factors n. This

is programmed by BS[2:0]. For optimum bias values, n can be calculated from:

Changing the bias system from the optimum will have a consequence on the contrast and viewing angle. One reason to

come away from the optimum would be to reduce the required VOP. A compromise between contrast and VOP must be

found for any particular application.

Table 3

Programming the required bias system

M[2]

M[1]

M[0]

MULTIPLEX RATE

ACTIVE ROWS

1 : 17

R0 to R15 and R64

1 : 26

R0 to R24 and R64

1 : 34

R0 to R32 and R64

1 : 49

R0 to R47 and R64

1:65

R0toR64

101

− 111

do not use

−

BS[2]

BS[1]

BS[0]

BIAS MODE

TYPICAL MUX RATES

0007

1/11

1 : 100

0016

1/10