C541U Datasheet, PDF (38/63 Pages) Siemens Semiconductor Group – 8 BIT CMOS MICROCONTROLLER

C541U
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.
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. Figure 19
shows the pins of the C541U-1E which are required for controlling of the OTP programming mode.
V_DD V_SS
A0-A7 /
A8-A12
PALE
PMSEL0
PMSEL1
XTAL1
XTAL2
Port 2
Port 0
C541U
D0-D7
EA/V_PP
PROG
PRD
RESET
PSEN
PSEL
Figure 19
Programming Mode Configuration
Semiconductor Group
36