
Semiconductor Group
42
1997-10-01
C540U
C541U
XTAL1
21
24
I
XTAL1
Input to the oscillator amplifier.
A0/A8 -
A7
24 - 31
28 - 35
I
Address lines
P2.0-7 are used as multiplexed address input lines
A0-A7 and A8-A12. A8-A12 must be latched with
PALE. Address A12 is requred only for the C541U.
PSEN
32
38
I
Program store enable
This input must be at static “0“ level during the whole
programming mode.
PROG
33
39
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
35
42
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
.
Data lines 0-7
During programming mode, data bytes are read or
written from or to the C540U/C541U via the
bidirectional D0-7 lines which are located at port 0.
D0 - 7
43 - 38
50 - 43
I/O
V
SS
9, 22
11, 25
–
Circuit ground potential
must be applied to these pins in programming mode.
V
CC
8, 23
10, 26
–
Power supply terminal
must be applied to these pins in programming mode.
N.C.
1, 12,,
34, 44
1 - 9, 14,
15, 27, 36,
37, 40, 41,
52
–
Not Connected
These pins should not be connected in programming
mode.
GND
17 - 19
20 - 22
I
Ground pins
In programming mode these pins must be connected
to
V
IL
level.
*) I = Input
O = Output
Table 9
Pin Definitions and Functions in Programming Mode
(cont’d)
Symbol
Pin Numbers
I/O*) Function
P-LCC-44 P-SDIP-52