datasheetbank_Logo     Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site

8051AHP View Datasheet(PDF) - Intel

Part NameDescriptionManufacturer
8051AHP MCS@51 8-BIT CONTROL-ORIENTED MICROCONTROLLERS Intel
Intel Intel
8051AHP Datasheet PDF : 21 Pages
First Prev 11 12 13 14 15 16 17 18 19 20
MCS@51 CONTROLLER
EPROM Security
The security feature consists of a ‘locking” bit which
when programmed denies electrical access by any
external means to the on-chip Program Memory.
The bit is programmed as shown in Figure 7. The
setup and procedure are the same as for normal
EPROM programming, except that P2.6 is held at a
logic high, Porl O,Port 1 and pins P2.O–P2.3 may be
in any state. The other pins should be held at the
“Security” levels indicated in Table 3.
Once the Security Bit has been programmed, it can
be cleared only by full erasure of the Program Mem-
ory. While it is programmed, the internal Program
Memory can not be read out, the device can not be
further programmed, and it cannot executeout of
externalprogrammemory.Erasing the EPROM,
thus clearing the Security Bit, restores the device’s
full functionality. It can then be reprogrammed.
Erasure Characteristics
Erasure of the EPROM begins to occur when the
device is exposed to light with wavelengths shorter
than approximately 4,000 Angstroms. Since sunlight
and fluorescent lighting have wavelengths in this
range, exposure to these light sources over an ex-
tended time (about 1 week in sunlight, or 3 years in
room-level fluorescent lighting) could cause inadver-
tent erasure. If an application subjects the device to
this type of exposure, it is suggested that an opaque
label be placed over the window.
X = OGN’T CARE”
+5V
o
f
X
{:
VIM
Vcc
PI
P2.0-
P2.3
P2.4
P2.5
‘-m
x
8751H
ALE
ALE/PROO
50 ma PULSE TO GND
P2.6
P2,7
fi +
EAYPP
XTAU
m
RST —
WH1
XTAL1
Vss
*
7 PSEN
*
272318-13
Figure7. Programmingthe SecurityBit
The recommended erasure procedure is exposure
to ultraviolet light (at 2537 Angstroms) to an integrat-
ed dose of at least 15 W-sec/cm2. Exposing the
EPROM to an ultraviolet lamp of 12,000 pW/cm2
rating for 20 to 30 minutes, at a distance of about
1 inch, should be sufficient.
Erasure leaves the array in an all 1‘s state.
EPROM PROGRAMMING AND VERIFICATION CHARACTERISTICS
TA = 21°C to 27”C; VCC = 5V + 10%; VSS = OV
Symbol
Parameter
Min
Max
VPP
Programming Supply Voltage
20.5
21.5
IPP
Programming Supply Current
30
1/TCLCL
Oscillator Frequency
4
6
TAVGL
Address Setup to PROG Low
46TCLCL
TGHAX
Address Hold after PROG
48TCLCL
TDVGL
Data Setup to PROG Low
48TCLCL
TGHDX
Data Hold after~
48TCLCL
TEHSH
P2.7 (ENABLE) High to VPP
48TCLCL
TSHGL
VPP Setup to PROG Low
10
TGHSL
VPP Hold after PROG
10
TGLGH
PROG Width
45
55
TAVQV
Address to Data Valid
48TCLCL
TELQV
ENABLE Low to Data Valid
48TCLCL
TEHQZ
Data Float after ENABLE
o
48TCLCL
Unita
v
mA
MHz
ps
ps
ms
15
Direct download click here

 

Share Link : 

All Rights Reserved © datasheetbank.com 2014 - 2020 [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]