M27256 STMICROELECTRONICS | Alldatasheet

Document overview

  • Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
  • PDF pages: 10

Technical content

This is information on a product still in production but not recommended for new designs. M27256 NMOS 256 Kbit (32Kb x 8) UV EPROM I FAST ACCESS TIME: 170ns I EXTENDED TEMPERATURE RANGE I SINGLE 5V SUPPLY VOLTAGE I LOW STANDBY CURRENT: 40mA max I TTL COMPATIBLE DURING READ and PROGRAM I FAST PROGRAMMING ALGORITHM I ELECTRONIC SIGNATURE I PROGRAMMING VOLTAGE: 12V

DESCRIPTION

The M27256 is a 262,144 bit UV erasable and electrically programmable memory EPROM. It is organized as 32.768 words by 8 bits. The M27256 is housed in a 28 pin Window Ceram- ic Frit-Seal Dual-in-Line package. The transparent lid allows the user to expose the chip to ultraviolet light to erase the bit pattern. A new pattern can then be written to the device by following the pro- gramming procedure. Figure 1. Logic Diagram

Figure 2. DIP Pin Connections may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents. Table 2. Absolute Maximum Ratings control and should be used for device selection. dresses have been stable for at least tAVQV -tGLQV .

from a particular memory device. EPROMs require careful decoupling of the devices. by the inductive effects of PCB traces. EPROM), all bits of the M27256 are in the “1" state. Table 3. Operating Modes Table 4. Electronic Signature

Note: 1. VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP . Table 6. Read Mode DC Characteristics (1) Notes:1. VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP .

  1. Sampled only, not 100% tested.

Note. 1. VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP . Table 8. Programming Mode DC Characteristics (1) Notes. 1. VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP .

  1. The Initial Program Pulse width tolerance is 1 ms ± 5%.
  2. The length of the Over-program Pulse varies from 2.85 ms to 78.95 ms, depending on the multiplication value of the iteration counter.
  3. Sampled only, not 100% tested.

Table 9. Programming Mode AC Characteristics (1)

VIH), and VPP = 12.5V. The outputs will be in a Hi-z state according to the signal presented to G. There- fore, all devices with VPP = 12.5V and G = VIL will present data on the bus independent of the E state. When parallel programming several devices which share the common bus, VPP should be lowered to VCC (6V) and the normal read mode used to exe- cute a program verify. Electronic Signature The Electronic Signature mode allows the reading out of a binary code from an EPROM that will identify its manufacturer and type. This mode is intended for use by programming equipment for the purpose of automatically matching the device to be programmed with its corresponding programming algorithm. This mode is functional in the 25°C ± 5°C ambient temperature range that is required when programming the M27256. To activate this mode, the programming equipment must force 11.5V to 12.5V on address line A9 of the M27256. Two identifier bytes may then be sequenced from the device outputs by toggling address line A0 from V IL to VIH. All other address lines must be held at VIL during Electronic Signature mode. Byte 0 (A0 = VIL) represents the manufacturer code and byte 1 (A0 = VIH) the device identifier code. For the STMi- croelectronics M27256, these two identifier bytes are given below. ERASURE OPERATION (applies to UV EPROM) The erasure characteristic of the M27256 is such that erasure begins when the cells are exposed to light with wavelengths shorter than approximately 4000 Å. It should be noted that sunlight and some type of fluorescent lamps have wavelengths in the 3000-4000 Å range. Research shows that constant exposure to room level fluorescent lighting could erase a typical M27256 in about 3 years, while it would take approximately 1 week to cause erasure when exposed to direct sunlight. If the M27256 is to be exposed to these types of lighting conditions for extended periods of time, it is suggested that opaque lables be put over the M27256 window to prevent unintentional erasure. The recommended erasure procedure for the M27256 is exposure to short wave ultraviolet light which has wavelength 2537 Å. The integrated dose (i.e. UV intensity x exposure time) for erasure should be a minimum of 15 W-sec/cm 2. The erasure time with this dosage is approximately 15 to 20 minutes using an ultra- violet lamp with 12000 µW/cm 2 power rating. The M27256 should be placed within 2.5cm (1 inch) of the lamp tubes during the erasure. Some lamps have a filter on their tubes which should be re- moved before erasure. Speed and VCC Tolerance -1 170 ns, 5V ±5% -2 200 ns, 5V ±5% blank 250 ns, 5V ±5% -3 300 ns, 5V ±5% -4 400 ns, 5V ±5% -20 200 ns, 5V ±10% -25 250 ns, 5V ±10% Package F FDIP28W Temperature Range 1 0 to 70 °C 6 –40 to 85 °C Example: M27256 -1 F 1 ORDERING INFORMATION SCHEME For a list of available options (Speed, VCC Tolerance, Package, etc) refer to the current Memory Shortform catalogue. For further information on any aspect of this device, please contact STMicroelectronics Sales Office nearest to you. DEVICE OPERATION (cont’d) M27256

A L B1 B e1 D S E1 E N Cα eA Symb mm inches Typ Min Max Typ Min Max A 5.71 0.225 A1 0.50 1.78 0.020 0.070 A2 3.90 5.08 0.154 0.200 B 0.40 0.55 0.016 0.022 B1 1.17 1.42 0.046 0.056 C 0.22 0.31 0.009 0.012 D 38.10 1.500 E 15.40 15.80 0.606 0.622 E1 13.05 13.36 0.514 0.526 eA 16.17 18.32 0.637 0.721 L 3.18 4.10 0.125 0.161 S 1.52 2.49 0.060 0.098 α 4° 15° 4° 15° N2 8 2 8 Drawing is not to scale FDIP28W - 28 pin Ceramic Frit-seal DIP , with window M27256

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is registered trademark of STMicroelectronics All other names are the property of their respective owners  2000 STMicroelectronics - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A.