C541U_99 Datasheet, PDF (172/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

OTP Memory Operation
C541U
10 OTP Memory Operation
The C541U contains a 8k byte one-time programmable (OTP) program memory. With the C541U
fast programming cycles are achieved (1 byte in 100 µsec). Also several levels of OTP memory
protection can be selected.
This chapter describes in detail the C541U programmimg interface.
10.1 Programming Configuration
For programming of the device, the C541U must be put into the programming mode. This typically
is done not in-system but in a special programming hardware. In the programming mode the C541U
operates as a slave device similar as an EPROM standalone memory device and must be controlled
with address/data information, control lines, and an external 11.5V programming voltage.
In the programming mode port 0 provides the bidirectional data lines and port 2 is used for the
multiplexed address inputs. The upper address information at port 2 is latched with the signal PALE.
For basic programming mode selection the inputs RESET, PSEN, EA/V_PP, ALE, PMSEL1/0, and
PSEL are used. Further, the inputs PMSEL1,0 are required to select the access types (e.g.
program/verify data, write lock bits, ....) in the programming mode. In programming mode V_DD/V_SS
and a clock signal at the XTAL pins must be applied to the C541U. The 11.5V external programming
voltage is input through the EA/V_PP pin.
Figure 10-1 shows the pins of the C541U which are required for controlling of the OTP
programming mode.
A0-A7 /
A8-A12
PALE
PMSEL0
PMSEL1
XTAL1
XTAL2
V_DD V_SS
Port 2
Port 0
C541U
D0-D7
EA/V_PP
PROG
PRD
RESET
PSEN
PSEL
Figure 10-1
C541U Programming Mode Configuration
Semiconductor Group
10-1
1997-10-01