C541U Datasheet, PDF (41/63 Pages) Siemens Semiconductor Group – 8 BIT CMOS MICROCONTROLLER

C541U
Table 8
Pin Definitions and Functions in Programming Mode (cont’d)
Symbol Pin Num- I/O*) Function
bers
P-LCC-44
A0/A8 - 24 - 31 I
A7
Address lines
P2.0-7 are used as multiplexed address input lines A0-A7 and A8-
A12. A8-A12 must be latched with PALE.
PSEN
32
I
Program store enable
This input must be at static “0“ level during the whole programming
mode.
PROG 33
I
Programming mode write strobe
This input is used in programming mode as a write strobe for OTP
memory program and lock bit write operations During basic
programming mode selection a low level must be applied to PROG.
EA/V_PP
D0 - 7
35
43 - 36
I
External Access / Programming voltage
This pin must be at 11.5 V (V_PP) voltage level during programming
of an OTP memory byte or lock bit. During an OTP memory read
operation this pin must be at high level (V_IH). This pin is also used
for basic programming mode selection. At basic programming
mode selection a low level must be applied to EA/V_PP.
I/O Data lines 0-7
During programming mode, data bytes are read or written from or
to the C541U via the bidirectional D0-7 lines which are located at
port 0.
V_SS
9, 22
– Circuit ground potential
must be applied to these pins in programming mode.
V_DD
8, 23
– Power supply terminal
must be applied to these pins in programming mode.
N.C.
1 - 7, 12,, –
34, 44
Not Connected
These pins should not be connected in programming mode.
GND
17 - 19 I
*) I = Input
O = Output
Ground pins
In programming mode these pins must be connected to V_IL level.
Semiconductor Group
39