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| AT28C256 Features * * * * * * * * * * * Fast Read Access Time - 150 ns Automatic Page Write Operation Internal Address and Data Latches for 64-Bytes Internal Control Timer Fast Write Cycle Times Page Write Cycle Time: 3 ms or 10 ms Maximum 1 to 64-Byte Page Write Operation Low Power Dissipation 50 mA Active Current 200 A CMOS Standby Current Hardware and Software Data Protection DATA Polling for End of Write Detection High Reliability CMOS Technology Endurance: 104 or 105 Cycles Data Retention: 10 Years Single 5V 10% Supply CMOS and TTL Compatible Inputs and Outputs JEDEC Approved Byte-Wide Pinout Full Military, Commercial, and Industrial Temperature Ranges 256K (32K x 8) Paged CMOS E2PROM Description The AT28C256 is a high-performance Electrically Erasable and Programmable Read Only Memory. Its 256K of memory is organized as 32,768 words by 8 bits. Manufactured with Atmel's advanced nonvolatile CMOS technology, the device offers access times to 150 ns with power dissipation of just 440 mW. When the device is deselected, the CMOS standby current is less than 200 A. (continued) Pin Configurations Pin Name A0 - A14 CE OE WE I/O0 - I/O7 NC DC Function Addresses Chip Enable Output Enable Write Enable Data Inputs/Outputs No Connect Don't Connect TSOP Top View AT28C256 PGA Top View LCC, PLCC Top View CERDIP, PDIP, FLATPACK, SOIC Top View Note: PLCC package pins 1 and 17 are DON'T CONNECT. 0006F 2-217 Description (Continued) The AT28C256 is accessed like a Static RAM for the read or write cycle without the need for external components. The device contains a 64-byte page register to allow writing of up to 64-bytes simultaneously. During a write cycle, the addresses and 1 to 64-bytes of data are internally latched, freeing the address and data bus for other operations. Following the initiation of a write cycle, the device will automatically write the latched data using an internal control timer. The end of a write cycle can be detected by DATA POLLING of I/O7. Once the end of a write cycle has been detected a new access for a read or write can begin. Atmel's 28C256 has additional features to ensure high quality and manufacturability. The device utilizes internal error correction for extended endurance and improved data retention characteristics. An optional software data protection mechanism is available to guard against inadvertent writes. The device also includes an extra 64-bytes of E2PROM for device identification or tracking. Block Diagram Absolute Maximum Ratings* Temperature Under Bias................. -55C to +125C Storage Temperature...................... -65C to +150C All Input Voltages (including NC Pins) with Respect to Ground ................... -0.6V to +6.25V All Output Voltages with Respect to Ground .............-0.6V to VCC + 0.6V Voltage on OE and A9 with Respect to Ground ................... -0.6V to +13.5V *NOTICE: Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2-218 AT28C256 AT28C256 Device Operation READ: The AT28C256 is accessed like a Static RAM. When CE and OE are low and WE is high, the data stored at the memory location determined by the address pins is asserted on the outputs. The outputs are put in the high impedance state when either CE or OE is high. This dualline control gives designers flexibility in preventing bus contention in their system. BYTE WRITE: A low pulse on the WE or CE input with CE or WE low (respectively) and OE high initiates a write cycle. The address is latched on the falling edge of CE or WE, whichever occurs last. The data is latched by the first rising edge of CE or WE. Once a byte write has been started it will automatically time itself to completion. Once a programming operation has been initiated and for the duration of tWC, a read operation will effectively be a polling operation. PAGE WRITE: The page write operation of the AT28C256 allows 1 to 64-bytes of data to be written into the device during a single internal programming period. A page write operation is initiated in the same manner as a byte write; the first byte written can then be followed by 1 to 63 additional bytes. Each successive byte must be written within 150 s (tBLC) of the previous byte. If the tBLC limit is exceeded the AT28C256 will cease accepting data and commence the internal programming operation. All bytes during a page write operation must reside on the same page as defined by the state of the A6 - A14 inputs. For each WE high to low transition during the page write operation, A6 - A14 must be the same. The A0 to A5 inputs are used to specify which bytes within the page are to be written. The bytes may be loaded in any order and may be altered within the same load period. Only bytes which are specified for writing will be written; unnecessary cycling of other bytes within the page does not occur. DATA POLLING: The AT28C256 features DATA Polling to indicate the end of a write cycle. During a byte or page write cycle an attempted read of the last byte written will result in the complement of the written data to be presented on I/O7. Once the write cycle has been completed, true data is valid on all outputs, and the next write cycle may begin. DATA Polling may begin at anytime during the write cycle. TOGGLE BIT: In addition to DATA Polling the AT28C256 provides another method for determining the end of a write cycle. During the write operation, successive attempts to read data from the device will result in I/O6 toggling between one and zero. Once the write has completed, I/O6 will stop toggling and valid data will be read. Reading the toggle bit may begin at any time during the write cycle. DATA PROTECTION: If precautions are not taken, inadvertent writes may occur during transitions of the host system power supply. Atmel has incorporated both hardware and software features that will protect the memory against inadvertent writes. HARDWARE PROTECTION: Hardware features protect against inadvertent writes to the AT28C256 in the following ways: (a) VCC sense - if VCC is below 3.8V (typical) the write function is inhibited; (b) VCC power-on delay - once VCC has reached 3.8V the device will automatically time out 5 ms (typical) before allowing a write: (c) write inhibit holding any one of OE low, CE high or WE high inhibits write cycles; (d) noise filter - pulses of less than 15 ns (typical) on the WE or CE inputs will not initiate a write cycle. SOFTWARE DATA PROTECTION: A software controlled data protection feature has been implemented on the AT28C256. When enabled, the software data protection (SDP), will prevent inadvertent writes. The SDP feature may be enabled or disabled by the user; the AT28C256 is shipped from Atmel with SDP disabled. SDP is enabled by the host system issuing a series of three write commands; three specific bytes of data are written to three specific addresses (refer to Software Data Protection Algorithm). After writing the 3-byte command sequence and after tWC the entire AT28C256 will be protected against inadvertent write operations. It should be noted, that once protected the host may still perform a byte or page write to the AT28C256. This is done by preceding the data to be written by the same 3-byte command sequence used to enable SDP. Once set, SDP will remain active unless the disable command sequence is issued. Power transitions do not disable SDP and SDP will protect the AT28C256 during power-up and power-down conditions. All command sequences must conform to the page write timing specifications. The data in the enable and disable command sequences is not written to the device and the memory addresses used in the sequence may be written with data in either a byte or page write operation. After setting SDP, any attempt to write to the device without the 3-byte command sequence will start the internal write timers. No data will be written to the device; however, for the duration of tWC, read operations will effectively be polling operations. (continued) 2-219 Device Operation (Continued) DEVICE IDENTIFICATION: A n e x t r a 6 4 - b y t e s o f E2PROM memory are available to the user for device identification. By raising A9 to 12V 0.5V and using address locations 7FC0H to 7FFFH the additional bytes may be written to or read from in the same manner as the regular memory array. OPTIONAL CHIP ERASE MODE: The entire device can be erased using a 6-byte software code. Please see Software Chip Erase application note for details. DC and AC Operating Range AT28C256-15 Com. Operating Temperature (Case) VCC Power Supply Ind. Mil. 0C - 70C -40C - 85C -55C - 125C 5V 10% AT28C256-20 0C - 70C -40C - 85C -55C - 125C 5V 10% AT28C256-25 0C - 70C -40C - 85C -55C - 125C 5V 10% -55C - 125C 5V 10% AT28C256-35 Operating Modes Mode Read Write (2) CE VIL VIL VIH X X X VIL OE VIL VIH X (1) WE VIH VIL X VIH X X VIL I/O DOUT DIN High Z Standby/Write Inhibit Write Inhibit Write Inhibit Output Disable Chip Erase X VIL VIH VH (3) High Z High Z Notes: 1. X can be VIL or VIH. 2. Refer to AC Programming Waveforms. 3. VH = 12.0V 0.5V. DC Characteristics Symbol ILI ILO ISB1 ISB2 ICC VIL VIH VOL VOH Parameter Input Load Current Output Leakage Current VCC Standby Current CMOS VCC Standby Current TTL VCC Active Current Input Low Voltage Input High Voltage Output Low Voltage Output High Voltage IOL = 2.1 mA IOH = -400 A 2.4 2.0 .45 Condition VIN = 0V to VCC + 1V VI/O = 0V to VCC CE = VCC - 0.3V to VCC + 1V CE = 2.0V to VCC + 1V f = 5 MHz; IOUT = 0 mA Com., Ind. Mil. Min Max 10 10 200 300 3 50 0.8 Units A A A A mA mA V V V V 2-220 AT28C256 AT28C256 AC Read Characteristics AT28C256-15 AT28C256-20 AT28C256-25 AT28C256-35 Symbol tACC tCE tOE tDF tOH (1) (2) (3, 4) Parameter Address to Output Delay CE to Output Delay OE to Output Delay CE or OE to Output Float Output Hold from OE, CE or Address, whichever occurred first Min Max Min Max Min Max Min Max Units ns ns ns ns ns 150 150 0 0 0 70 50 0 0 0 200 200 80 55 0 0 0 250 250 100 60 0 0 0 350 350 100 70 AC Read Waveforms (1, 2, 3, 4) Notes: 1. CE may be delayed up to tACC - tCE after the address transition without impact on tACC. 2. OE may be delayed up to tCE - tOE after the falling edge of CE without impact on tCE or by tACC - tOE after an address change without impact on tACC. 3. tDF is specified from OE or CE whichever occurs first (CL = 5 pF). 4. This parameter is characterized and is not 100% tested. Input Test Waveforms and Measurement Level Output Test Load tR, tF < 5ns Pin Capacitance (f = 1 MHz, T = 25C) (1) Typ CIN COUT Note: Max 6 12 Units pF pF Conditions VIN = 0V VOUT = 0V 4 8 1. This parameter is characterized and is not 100% tested. 2-221 AC Write Characteristics Symbol tAS, tOES tAH tCS tCH tWP tDS tDH, tOEH tDV Note: Parameter Address, OE Set-up Time Address Hold Time Chip Select Set-up Time Chip Select Hold Time Write Pulse Width (WE or CE) Data Set-up Time Data, OE Hold Time Time to Data Valid Min 0 50 0 0 100 50 0 NR (1) Max Units ns ns ns ns ns ns ns 1. NR = No Restriction AC Write Waveforms WE Controlled CE Controlled 2-222 AT28C256 AT28C256 Page Mode Characteristics Symbol tWC tAS tAH tDS tDH tWP tBLC tWPH Parameter Write Cycle Time Address Set-up Time Address Hold Time Data Set-up Time Data Hold Time Write Pulse Width Byte Load Cycle Time Write Pulse Width High 50 AT28C256 AT28C256F 0 50 50 0 100 150 Min Max 10 3.0 Units ms ms ns ns ns ns ns s ns Page Mode Write Waveforms (1, 2) Notes: 1. A6 through A14 must specify the same page address during each high to low transition of WE (or CE). 2. OE must be high only when WE and CE are both low. Chip Erase Waveforms tS = tH = 5 sec (min.) tW = 10 msec (min.) VH = 12.0V 0.5V 2-223 Software Data Protection Enable Algorithm (1) LOAD DATA AA TO ADDRESS 5555 LOAD DATA 55 TO ADDRESS 2AAA LOAD DATA A0 TO ADDRESS 5555 LOAD DATA XX TO ANY ADDRESS (4) LOAD LAST BYTE TO LAST ADDRESS Software Data Protection Disable Algorithm (1) LOAD DATA AA TO ADDRESS 5555 LOAD DATA 55 TO ADDRESS 2AAA LOAD DATA 80 TO ADDRESS 5555 LOAD DATA AA TO ADDRESS 5555 LOAD DATA 55 TO ADDRESS 2AAA LOAD DATA 20 TO ADDRESS 5555 LOAD DATA XX TO ANY ADDRESS (4) LOAD LAST BYTE TO LAST ADDRESS WRITES ENABLED (2) ENTER DATA PROTECT STATE Notes for software program code: 1. Data Format: I/O7 - I/O0 (Hex); Address Format: A14 - A0 (Hex). 2. Write Protect state will be activated at end of write even if no other data is loaded. 3. Write Protect state will be deactivated at end of write period even if no other data is loaded. 4. 1 to 64-bytes of data are loaded. EXIT DATA PROTECT STATE (3) Software Protected Write Cycle Waveforms (1, 2) Notes: 1. A6 through A14 must specify the same page address during each high to low transition of WE (or CE) after the software code has been entered. 2. OE must be high only when WE and CE are both low. 2-224 AT28C256 AT28C256 Data Polling Characteristics (1) Symbol tDH tOEH tOE tWR Parameter Data Hold Time OE Hold Time OE to Output Delay (2) Write Recovery Time 0 2. See AC Read Characteristics. Min 0 0 Typ Max Units ns ns ns ns Notes: 1. These parameters are characterized and not 100% tested. Data Polling Waveforms Toggle Bit Characteristics (1) Symbol tDH tOEH tOE tOEHP tWR Parameter Data Hold Time OE Hold Time OE to Output Delay OE High Pulse Write Recovery Time (2) Min 10 10 150 0 Typ Max Units ns ns ns ns ns Notes: 1. These parameters are characterized and not 100% tested. 2. See AC Read Characteristics. Toggle Bit Waveforms (1, 2, 3) Notes: 1. Toggling either OE or CE or both OE and CE will operate toggle bit. 2. Beginning and ending state of I/O6 will vary. 3. Any address location may be used but the address should not vary. 2-225 2-226 AT28C256 AT28C256 Ordering Information (2) tACC (ns) 150 ICC (mA) Active 50 Standby 0.2 AT28C256(E,F)-15JC AT28C256(E,F)-15PC AT28C256(E,F)-15SC AT28C256(E,F)-15TC AT28C256(E,F)-15JI AT28C256(E,F)-15PI AT28C256(E,F)-15SI AT28C256(E,F)-15TI 50 0.3 AT28C256(E,F)-15DM/883 AT28C256(E,F)-15FM/883 AT28C256(E,F)-15LM/883 AT28C256(E,F)-15UM/883 AT28C256(E,F)-20JC AT28C256(E,F)-20PC AT28C256(E,F)-20SC AT28C256(E,F)-20TC AT28C256(E,F)-20JI AT28C256(E,F)-20PI AT28C256(E,F)-20SI AT28C256(E,F)-20TI 50 0.3 AT28C256(E,F)-20DM/883 AT28C256(E,F)-20FM/883 AT28C256(E,F)-20LM/883 AT28C256(E,F)-20UM/883 AT28C256(E,F)-25JC AT28C256(E,F)-25PC AT28C256-W AT28C256(E,F)-25JI AT28C256(E,F)-25PI 50 0.3 AT28C256(E,F)-25DM/883 AT28C256(E,F)-25FM/883 AT28C256(E,F)-25LM/883 AT28C256(E,F)-25UM/883 AT28C256(E,F)-35UM/883 AT28C256-W Ordering Code Package 32J 28P6 28S 28T 32J 28P6 28S 28T 28D6 28F 32L 28U 32J 28P6 28S 28T 32J 28P6 28S 28T 28D6 28F 32L 28U 32J 28P6 DIE 32J 28P6 28D6 28F 32L 28U 28U DIE Operation Range Commercial (0C to 70C) Industrial (-40C to 85C) Military/883C Class B, Fully Compliant (-55C to 125C) Commercial (0C to 70C) 200 50 0.2 Industrial (-40C to 85C) Military/883C Class B, Fully Compliant (-55C to 125C) Commercial (0C to 70C) Industrial (-40C to 85C) Military/883C Class B, Fully Compliant (-55C to 125C) 250 50 0.2 50 0.2 Commercial (0C to 70C) (continued) 2-227 Ordering Information (Continued) tACC (ns) 150 (3) ICC (mA) Active 50 Standby 0.35 5962-88525 16 UX 5962-88525 16 XX 5962-88525 16 YX 5962-88525 16 ZX 5962-88525 15 UX 5962-88525 15 XX 5962-88525 15 YX 5962-88525 15 ZX 5962-88525 14 UX 5962-88525 14 XX 5962-88525 14 YX 5962-88525 14 ZX 50 0.35 5962-88525 08 UX 5962-88525 08 XX 5962-88525 08 YX 5962-88525 08 ZX 5962-88525 07 UX 5962-88525 07 XX 5962-88525 07 YX 5962-88525 07 ZX 5962-88525 06 UX 5962-88525 06 XX 5962-88525 06 YX 5962-88525 06 ZX 200 (3) 50 0.35 5962-88525 12 UX 5962-88525 12 XX 5962-88525 12 YX 5962-88525 12 ZX 5962-88525 04 UX 5962-88525 04 XX 5962-88525 04 YX 5962-88525 04 ZX 5962-88525 13 UX 5962-88525 13 XX 5962-88525 13 YX 5962-88525 13 ZX 5962-88525 11 UX 5962-88525 11 XX 5962-88525 11 YX 5962-88525 11 ZX Ordering Code Package 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F Operation Range Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) 50 0.35 250 (3) 50 0.35 (continued) 2-228 AT28C256 AT28C256 Ordering Information (Continued) tACC (ns) 250 ICC (mA) Active 50 Standby 0.35 5962-88525 05 UX 5962-88525 05 XX 5962-88525 05 YX 5962-88525 05 ZX 5962-88525 03 UX 5962-88525 03 XX 5962-88525 03 YX 5962-88525 03 ZX 300 50 0.35 5962-88525 10 UX 5962-88525 10 XX 5962-88525 10 YX 5962-88525 10 ZX 5962-88525 02 UX 5962-88525 02 XX 5962-88525 02 YX 5962-88525 02 ZX 5962-88525 09 UX 5962-88525 09 XX 5962-88525 09 YX 5962-88525 09 ZX 5962-88525 01 UX 5962-88525 01 XX 5962-88525 01 YX 5962-88525 01 ZX Ordering Code Package 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F Operation Range Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) Military/883C Class B, Fully Compliant (-55C to 125C) 50 0.35 350 50 0.35 50 0.35 Notes: 1. Electrical specifications for these speeds are defined by Standard Microcircuit Drawing 5962-88525. 2. See Valid Part Number table below. 3. SMD specifies Software Data Protection feature for device type, although Atmel product supplied to every device type in the SMD is 100% tested for this feature. Valid Part Numbers The following table lists standard Atmel products that can be ordered. Device Numbers AT28C256 AT28C256E AT28C256F AT28C256 AT28C256E AT28C256F AT28C256 AT28C256E AT28C256F AT28C256 Speed 15 15 15 20 20 20 25 25 25 - Package and Temperature Combinations JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 JC, JI, PC, PI, SC, SI, TC, TI, DM/883, FM/883, LM/883, UM/883 W 2-229 Package Type 28D6 28F 32J 32L 28P6 28S 28T 28U W 28 Lead, 0.600" Wide, Non-Windowed, Ceramic Dual Inline Package (Cerdip) 28 Lead, Non-Windowed, Ceramic Bottom-Brazed Flat Package (Flatpack) 32 Lead, Plastic J-Leaded Chip Carrier (PLCC) 32 Pad, Non-Windowed, Ceramic Leadless Chip Carrier (LCC) 28 Lead, 0.600" Wide, Plastic Dual Inline Package (PDIP) 28 Lead, 0.300" Wide, Plastic Gull Wing Small Outline (SOIC) 28 Lead, Plastic Thin Small Outline Package (TSOP) 28 Pin, Ceramic Pin Grid Array (PGA) Die Options Blank E F Standard Device: Endurance = 10K Write Cycles; Write Time = 10 ms High Endurance Option: Endurance = 100K Write Cycles Fast Write Option: Write Time = 3 ms 2-230 AT28C256 |
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