PCF8811MU/2DA/1 PHILIPS [NXP Semiconductors], PCF8811MU/2DA/1 Datasheet - Page 56

• Manufacturer Part Number: PCF8811MU/2DA/1
• Description: 80 x 128 pixels matrix LCD driver
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
22.2
The second feature is an OTP factory default setting for
the temperature coefficient selection (MMTC) in the basic
command set. This 3-bit value will be loaded from OTP
after leaving the power-save mode or by the refresh
command. The idea of this feature is to provide, in the
basic command set, the complete set of temperature
coefficients without an additional command. In the
extended command set the temperature coefficient can be
programmed as given in Table 16.
22.3
The module maker programming is performed in a special
mode: the calibration mode (CALMM). This mode is
entered via a special interface command, CALMM.
To prevent wrongful programming, a seal bit has been
implemented which prevents the device from entering the
calibration mode. This seal bit, once programmed, can not
be reversed, thus further changes in programmed values
are not possible.
Applying the programming voltages when not in CALMM
mode will have no effect on the programmed values.
Table 23 Seal bit definition
22.4
The OTP circuitry in the PCF8811 contains 9 bits of data:
5 for V
coefficient default setting in the basic command set MMTC
and 1 seal bit. The circuitry for 1-bit is called an OTP slice.
Each OTP slice consists of 2 main parts: the OTP cell (a
non-volatile memory cell) and the shift register cell (a
flip-flop). The OTP cells are only accessible through their
shift register cells: on the one hand both reading from and
writing to the OTP cells is performed with the shift register
cells, on the other hand only the shift register cells are
visible to the rest of the circuit. The basic OTP architecture
is shown in Fig.48.
2004 May 17
80
SEAL BIT
LCD
Temperature coefficient selection
Seal bit
OTP architecture
0
1
128 pixels matrix LCD driver
calibration (MMVOPCAL), 3 for the temperature
possible to enter calibration mode
calibration mode disabled
ACTION
56
This OTP architecture allows the following operations:
1. Reading data from the OTP cells. The content of the
2. Writing data to the OTP cells. First, all 9 bits of data are
3. Checking calibration without writing to the OTP cells.
The reading of data from the OTP cells is initiated by
either:
It should be noted that in both cases the reading operation
needs up to 5 ms to complete.
The shifting of data into the shift register is performed in
the special mode CALMM. In the PCF8811 the CALMM
mode is entered by the CALMM command. Once in the
CALMM mode the data is shifted into the shift register via
the interface at the rate of 1-bit per command. After
transmitting the last (9th) bit and exiting the CALMM mode,
the serial interface will return to the normal mode and all
other commands can be sent. Care should be taken that
9 bits of data (or a multiple of 9) are always transferred
before exiting the CALMM mode, otherwise the bits will be
in the wrong positions.
In the shift register the value of the seal bit is, like the
others, always zero at reset. To ensure that the security
feature works correctly, the CALMM command is disabled
until a refresh has been performed. Once the refresh is
completed, the seal bit value in the shift register will be
valid and permission to enter the CALMM mode can thus
be determined.
The 9 bits are shifted into the shift register in a predefined
order: first 5 bits of MMVOPCAL[4:0], 3 bits for MMTC[2:0]
and lastly the seal bit. The MSB is always first, thus the first
bit shifted is MMVOPCAL[4] and the two last bits are
MMTC[0] and the seal bit.
Exit from power-save mode
The ‘Refresh’ command (power control).
non-volatile OTP cells is transferred to the shift
register where upon it may affect the PCF8811
operation.
shifted into the shift register via the interface. The
content of the shift register is then transferred to the
OTP cells (there are some limitations related to storing
data in these cells; see Section 22.7).
Shifting data into the shift register allows the effects on
the V
LCD
voltage to be observed.
Product specification
PCF8811