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| AT28HC256 Features * * * * * * * * * * * Fast Read Access Time - 70 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 80 mA Active Current 3 mA 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 256 (32K x 8) High Speed CMOS E2PROM Description The AT28HC256 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 AT28HC256 offers access times to 70 ns with power dissipation of just 440 mW. When the AT28HC256 is deselected, the standby current is less than 5 mA. (continued) Pin Configurations Pin Name A0 - A14 CE OE WE I/O0 - I/O7 NC DC Function Addresses Chip Enable Output Enable Write Enable TSOP Top View AT28HC256 Data Inputs/Outputs No Connect Don't Connect PGA Top View CERDIP, PDIP, FLATPACK Top View LCC, PLCC Top View Note: PLCC package pins 1 and 17 are DON'T CONNECT. 0007F 2-279 Description (Continued) The AT28HC256 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 address and 1 to 64-bytes of data are internally latched, freeing the addresses 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 28HC256 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. 2-280 AT28HC256 AT28HC256 Device Operation READ: The AT28HC256 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: T h e p a g e w r i t e o p e r a t i o n o f t h e AT28HC256 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. That is, 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 AT28HC256 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: I n a d d i t i o n t o DATA P o l l i n g t h e AT28HC256 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. Testing the toggle bit may begin at any time during the write cycle. DATA PROTECTION: If precautions are not taken, inadvertent writes to any 5-volt-only nonvolatile memory may occur during transition 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 AT28HC256 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 AT28HC256. When enabled, the software data protection (SDP), will prevent inadvertent writes. The SDP feature may be enabled or disabled by the user; the AT28HC256 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 AT28HC256 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 AT28HC256. This is done by preceding the data to be written by the same 3-byte command sequence. Once set, SDP will remain active unless the disable command sequence is issued. Power transitions do not disable SDP and SDP will protect the AT28HC256 during power-up and power-down conditions. All command sequences must conform to the page write timing specifications. It should also be noted that 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 three 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) 2-281 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 AT28HC256-70 Operating Temperature (Case) VCC Power Supply Com. Ind. Mil. 5V 10% 0C - 70C -40C - 85C AT28HC256-90 0C - 70C -40C - 85C -55C - 125C 5V 10% AT28HC256-12 0C - 70C -40C - 85C -55C - 125C 5V 10% Operating Modes Mode Read Write (2) Standby/Write Inhibit Write Inhibit Write Inhibit Output Disable Chip Erase 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 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 TTL VCC Standby Current CMOS VCC Active Current Input Low Voltage Input High Voltage Output Low Voltage Output High Voltage IOL = 6.0 mA IOH = -4 mA 2.4 2.0 .45 Condition VIN = 0V to VCC + 1V VI/O = 0V to VCC CE = 2.0V to VCC + 1V CE = -3.0V to VCC + 1V f = 5 MHz; IOUT = 0 mA AT28HC256-90, -12 AT28HC256-70 AT28HC256-90, -12 Min Max 10 10 3 60 300 80 0.8 Units A A mA mA A mA V V V V 2-282 AT28HC256 AT28HC256 AC Read Characteristics AT28HC256-70 Symbol tACC tCE tOE tDF tOH (1) (2) (3, 4) AT28C256-90 Min Max AT28HC256-12 Min Max 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 Units ns ns ns ns ns 70 70 0 0 0 35 35 0 0 0 90 90 40 40 0 0 0 120 120 50 50 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 < 5 ns 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. 2-283 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 2-284 AT28HC256 AT28HC256 Page Mode Write 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 AT28HC256 AT28HC256F 0 50 50 0 100 150 Min Typ 5 2 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 2-285 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: 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. 2-286 AT28HC256 AT28HC256 Data Polling Characteristics (1) Symbol tDH tOEH tOE tWR Parameter Data Hold Time OE Hold Time OE to Output Delay (2) Min 0 0 0 Typ Max Units ns ns ns ns Write Recovery Time Notes: 1. These parameters are characterized and not 100% tested. 2. See AC Read Characteristics. 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 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. 2-287 2-288 AT28HC256 AT28HC256 Ordering Information (1) tACC (ns) 70 ICC (mA) Active 80 80 90 80 80 80 Standby 60 0.3 0.3 0.3 0.3 AT28HC256(E,F)-70JC AT28HC256(E,F)-70PC AT28HC256(E,F)-70JI AT28HC256(E,F)-70PI AT28HC256(E,F)-90JC AT28HC256(E,F)-90PC AT28HC256(E,F)-90JI AT28HC256(E,F)-90PI AT28HC256(E,F)-90DM/883 AT28HC256(E,F)-90FM/883 AT28HC256(E,F)-90LM/883 AT28HC256(E,F)-90UM/883 AT28HC256(E,F)-12JC AT28HC256(E,F)-12PC AT28HC256(E,F)-12SC AT28HC256(E,F)-12TC AT28HC256(E,F)-12JI AT28HC256(E,F)-12PI AT28HC256(E,F)-12SI AT28HC256(E,F)-12TI AT28HC256(E,F)-12DM/883 AT28HC256(E,F)-12FM/883 AT28HC256(E,F)-12LM/883 AT28HC256(E,F)-12UM/883 5962-88634 03 UX 5962-88634 03 XX 5962-88634 03 YX 5962-88634 03 ZX 5962-88634 04 UX 5962-88634 04 XX 5962-88634 04 YX 5962-88634 04 ZX 5962-88634 01 UX 5962-88634 01 XX 5962-88634 01 YX 5962-88634 01 ZX 5962-88634 02 UX 5962-88634 02 XX 5962-88634 02 YX 5962-88634 02 ZX Ordering Code Package 32J 28P6 32J 28P6 32J 28P6 32J 28P6 28D6 28F 32L 28U 32J 28P6 28S 28T 32J 28P6 28S 28T 28D6 28F 32L 28U 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F 28U 28D6 32L 28F Operation Range Commercial (0C to 70C) Industrial (-40C to 85C) Commercial (0C to 70C) Industrial (-40C to 85C) Military/883C Class B, Fully Compliant (-55C to 125C) Commercial (0C to 70C) 120 80 0.3 80 0.3 Industrial (-40C to 85C) 80 0.3 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) 90 80 0.3 80 0.3 120 80 0.3 80 0.3 Note: 1. See Valid Part Number table below. 2-289 Ordering Information Note Previous data sheets included the low power suffixes L, LE and LF on the AT28HC256 for 120 ns and 90 ns speeds. The low power parameters are now standard; therefore, the L, LE and LF suffixes are no longer required. Valid Part Numbers The following table lists standard Atmel products that can be ordered. Device Numbers AT28HC256 AT28HC256 AT28HC256E AT28HC256F AT28HC256 AT28HC256E AT28HC256F Speed 70 90 90 90 12 12 12 Package and Temperature Combinations JC, JI, PC, PI JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883 JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883 JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883 JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883 JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883 JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883 Package Type 28D6 28F 32J 32L 28P6 28S 28T 28U 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) 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 2-290 AT28HC256 |
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