COP8782C Datasheet, PDF (21/28 Pages) National Semiconductor (TI) – 8-Bit One-Time Programmable (OTP) Microcontroller

Development Support (Continued)
CUSTOMER RESPONSE CENTER
Complete product information and technical support is avail-
able from National’s customer response centers
CANADA U S Tel
email
[phone]
support tevm2 nsc com
EUROPE
email
europe support nsc com
Deutsch Tel a49 (0) 180-530 85 85
English Tel
a49 (0) 180-532 78 32
Fran ais Tel a49 (0) 180-532 93 58
Italiano Tel
a49 (0) 180-534 16 80
JAPAN
Tel
a81-043-299-2309
S E ASIA
Beijing Tel
(a86) 10-6856-8601
Shanghai Tel (a86) 21-6415-4092
Hong Kong Tel (a852) 2737-1600
Korea Tel
(a82) 2-3771-6909
Malaysia Tel (a60-4) 644-9061
Singapore Tel (a65) 255-2226
Taiwan Tel
a886-2-521-3288
AUSTRALIA Tel
(a61) 3-9558-9999
INDIA
Tel
(a91) 80-559-9467
Programming Considerations
In addition to the application program the ECON register
needs to be programmed as well The following tables pro-
vide examples of some ECON register values For more de-
tailed information refer to the ECON REGISTER section
EPROM Security Disabled
RAM
Memory
64 Bytes
128 Bytes
External
CKI
38
3A
RC
Oscillator
30
32
Crystal
Oscillator
20
22
RAM
Memory
64 Bytes
128 Bytes
EPROM Security Enabled
External
CKI
RC
Oscillator
18
10
1A
12
Crystal
Oscillator
00
02
EPROM programmer manufacturers may not all calculate a
‘‘checksum’’ the same way Before implementing an in-
house verification by comparing checksums need to ensure
how each programming system utilized calculates a check-
sum It is strongly recommended not to include the ECON
register in the checksum for not all programmers include
this byte in their calculated checksum
ERASING THE COP8780C EPROM
The EPROM program memory is erased by exposing the
transparent window on the UV erasable packages to an ul-
traviolet light source Erasure begins to occur when ex-
posed to light with wavelengths shorter than approximately
4000 Angstroms ( ) It should be noted that sunlight and
certain types of fluorescent lamps have wavelengths in the
3000 to 4000 range
After programming ‘‘truly opaque’’ labels should be placed
over the window of the device to prevent functional failure
due to the generation of photo currents erasure and exces-
sive HALT current The term ‘‘truly opaque’’ needs addition-
al clarification when used in the context of covering quartz
windows on these devices The typical white colored stick-
ers or labels are normally used for they are easy to write on
These stickers are not opaque but translucent they do let a
certain percentage of UV-light through The black write-pro-
tect labels supplied with 5 25 floppy disks work extremely
well If problems are encountered during programming (fails
blank check) or during normal operation (intermittent func-
tional or logical failures) need to determine first if an appro-
priate opaque label is being used to cover the quartz win-
dow at all times Note that the device will also draw more
current than normal (especially in HALT mode) when the
window of the device is not covered with an opaque label
The recommended erasure procedure for the device is ex-
posure to short wave ultraviolet light which has a wave-
length of 2537 The integrated dose (UV intensity c expo-
sure time) for erasure should be a minimum of 30W-sec
cm²
The device should be placed within one inch of the lamp
tubes during erasure Some lamps have a filter on their
tubes which should be removed before erasure The follow-
ing table shows the minimum erasure time for various light
intensities
Minimum Erasure Time
Light Intensity
(Micro-Watts cm²)
Erasure Time
(Minutes)
15 000
36
10 000
50
8 500
60
Does not include light intensity ramp up time
An erasure system should be calibrated periodically The
distance from lamp to device should be maintained at one
inch The erasure time increases as the square of the dis-
tance Lamps lose intensity as they age When a lamp has
aged the system should be checked to make certain that
adequate UV dosages are being applied for full erasure
Common symptoms of insufficient erasure are
 Inability to be programmed
 Operational malfunctions associated with V_CC tempera-
ture or clock frequency
 Loss of data in program memory
 A change in configuration values in the ECON register
21
http www national com