 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
27C256-20L Datasheet(PDF) 6 Page - Microchip Technology |
|
||||||||||||||||||||||||||||||
27C256-20L Datasheet(HTML) 6 Page - Microchip Technology |
|
|
6 / 12 page  27C256 DS11001L-page 6 © 1996 Microchip Technology Inc. 1.3 Standby Mode The standby mode is defined when the CE pin is high (VIH) and a program mode is not defined. When these conditions are met, the supply current will drop from 20 mA to 100 µA. 1.4 Output Enable This feature eliminates bus contention in multiple bus microprocessor systems and the outputs go to a high impedance when the following condition is true: • The OE pin is high and the program mode is not defined. 1.5 Erase Mode (U.V. Windowed Versions) Windowed products offer the ability to erase the mem- ory array. The memory matrix is erased to the all 1’s state when exposed to ultraviolet light. To ensure com- plete erasure, a dose of 15 watt-second/cm2 is required. This means that the device window must be placed within one inch and directly underneath an ultra- violet lamp with a wavelength of 2537 Angstroms, intensity of 12,000 µW/cm2 for approximately 20 min- utes. 1.6 Programming Mode The Express Algorithm has been developed to improve on the programming throughput times in a production environment. Up to ten 100-microsecond pulses are applied until the byte is verified. No overprogramming is required. A flowchart of the express algorithm is shown in Figure 1-3. Programming takes place when: a) VCC is brought to the proper voltage, b) VPP is brought to the proper VH level, c) the OE pin is high, and d) the CE pin is low. Since the erased state is “1” in the array, programming of “0” is required. The address to be programmed is set via pins A0-A14 and the data to be programmed is pre- sented to pins O0-O7. When data and address are sta- ble, a low going pulse on the CE line programs that location. 1.7 Verify After the array has been programmed it must be veri- fied to ensure all the bits have been correctly pro- grammed. This mode is entered when all the following conditions are met: a) VCC is at the proper level, b) VPP is at the proper VH level, c) the CE line is high, and d) the OE line is low. 1.8 Inhibit When programming multiple devices in parallel with dif- ferent data, only CE need be under separate control to each device. By pulsing the CE line low on a particular device, that device will be programmed; all other devices with CE held high will not be programmed with the data, although address and data will be available on their input pins. 1.9 Identity Mode In this mode specific data is output which identifies the manufacturer as Microchip Technology Inc. and device type. This mode is entered when Pin A9 is taken to VH (11.5V to 12.5V). The CE and OE lines must be at VIL. A0 is used to access any of the two non-erasable bytes whose data appears on O0 through O7. Pin Input Output Identity A0 0 7 O 6 O 5 O 4 O 3 O 2 O 1 O 0 H e x Manufacturer Device Type* VIL VIH 0 1 0 0 1 0 0 0 1 1 0 1 0 0 1 0 29 8C * Code subject to change |
Similar Part No. - 27C256-20L |
|
Similar Description - 27C256-20L |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.NET |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
