NTE2764 查看數據表（PDF） - NTE Electronics
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NTE2764 Datasheet PDF : 5 Pages
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Function (Cont’d):
The recommended erasure procedure for the NTE2764 is exposure to ultraviolet light with wave-
lengths of 2,537 Angstroms. The integrated dose (i.e. UV intensity x exposure time) for erasure
should be not less than 15W–sec/cm2. The erasure time is approximately 15 to 20 minutes using
an ultraviolet lamp of 12,000 µW/cm2 power rating.
During erasure, the NTE2764 should be placed within 1 inch of the lamp tubes. If the lamps have
filters on the tubes, the filters should be removed before erasure.
Operation:
The five operation modes of the NTE2764 are listed in the Mode Selection table. In READ mode, the
only power supply required is a +5V supply. During programming, all inputs are TTL levels except
for VPP which is pulsed from TTL level to 21V.
Read Mode:
When CE and OE are at low (0) level, READ is set and data is available at the outputs after tOE from
the falling edge of OE and tACC after setting the address.
Standby Mode:
The NTE2764 is placed in standby mode with the application of a high (1) level TTL signal to the CE
input. In this mode, the outputs are in a high impedance state, independent of the OE input. The active
power dissipation is reduced by 67% from 788mW to 262mW.
Programming:
Programming begins with erasing all data and consequently having all bits in the high (1) level state.
Data is then entered by programming a low (0) level TTL signal into the chosen bit location.
The NTE2764 is placed in programming mode by applying a low (0) level TTL signal to the CE and
PGM with Vpp at +21V. The data to be programmed is applied to the output pins in 8–bit parallel form
at TTL levels.
Any location can be programmed at any time, either individually, sequentially or at random.
When multiple NTE2764s are connected in parallel except for CE, individual NTE2764 can be pro-
grammed by applying a low (0) level TTL pulse to the PGM input of the desired NTE2764 to be pro-
grammed.
Programming of multiple NTE2764s in parallel with the same data is easily accomplished. All the like
inputs are tied together and programmed by applying a low (0) level TTL pulse to the PGM inputs.
Programming Inhibit Mode:
Programming multiple NTE2764 in parallel with different data is easier with the program inhibit mode.
Except for CE (or PGM) all like inputs (including OE) of the parallel NTE2764 may be common. Pro-
gramming is accomplished by applying a low (0) TTL–level program pulse to the CE (or PGM) input
with VPP at +21V. A high (1) level applied to the CE (or PGM) of the other NTE2764 will inhibit it from
being programmed.
Program Verify Mode:
A verify should be performed on the programmed bits to determine that the data was correctly pro-
grammed. The program verify can be performed with CE and OE at low (0) levels and PGM at high
(1) level.
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