PCF8545 datasheet(8/68 Pages) NXP

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NXP Semiconductors

PCF8545

Universal LCD driver for multiplex rates up to 1:8

7.1.2 Command: OTP-refresh

During production of the device, each IC is calibrated to achieve the specified accuracy

of the frame frequency. This calibration is performed on EPROM cells called One Time

Programmable (OTP) cells. The device reads these cells every time the OTP-refresh

command is sent. The OTP-refresh command has to be sent after a reset has been

made and before the display is enabled.

This command will be completed after a maximum of 30 ms and requires either the

internal or external clock to run. If the internal oscillator is not used, then a clock must

be supplied to the OSCCLK pin. If the OTP-refresh instruction is sent and no clock is

present, then the request is stored until a clock is available.

Remark: It is recommended not to enter power-down mode during the OTP refresh

cycle.

Bit

Symbol

Value

Description

7 to 0

1111 0000

fixed value

Table 6. OTP-refresh - OTP-refresh command bit description

7.1.3 Command: mode-settings

Bit

Symbol

Value

Description

7 to 4

0101

fixed value

backplane swapping

0[1]

backplane configuration 0

BPS

backplane configuration 1

set inversion mode

0[1][2]

Driving scheme A: LCD line inversion mode

INV

Driving scheme B: LCD frame inversion

mode

set power mode

power-down mode; backplane and segment

outputs are connected to VSS and the

internal oscillator is switched off

0[1]

power-up mode

display switch

0[1]

display disabled; backplane and segment

outputs are connected to VSS

display enabled

Table 7. Mode-settings - mode settings command bit description

[1]

Default value.

[2]

See Section 7.1.3.2.

7.1.3.1 Backplane swapping

Backplane swapping can be configured with the BPS bit (see Table 7). It moves the

location of the backplane and the associated segment outputs from one side of the

PCF8545

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 2 — 4 October 2021

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