Obsolete Device 27C256 256K (32K x 8) CMOS EPROM 30 31 1 32 2 A7 A12 VPP NU Vcc A14 A13 3 4 5 29 6 28 7 27 8 9 10 11 26 25 24 23 A8 A9 A11 NC OE A10 CE O7 O6 20 19 18 17 21 16 22 13 15 12 14 A6 A5 A4 A3 A2 A1 A0 NC O0 DIP/SOIC VPP A12 A7 A6 A5 A4 A3 A2 A1 A0 O0 O1 O2 VSS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 27C256 DESCRIPTION PLCC 27C256 • High speed performance - 90 ns access time available • CMOS Technology for low power consumption - 20 mA Active current - 100 µA Standby current • Factory programming available • Auto-insertion-compatible plastic packages • Auto ID aids automated programming • Separate chip enable and output enable controls • High speed “express” programming algorithm • Organized 32K x 8: JEDEC standard pinouts - 28-pin Dual-in-line package - 32-pin PLCC Package - 28-pin SOIC package - Tape and reel • Data Retention > 200 years • Available for the following temperature ranges: - Commercial: 0°C to +70°C - Industrial: -40°C to +85°C - Automotive: -40°C to +125°C PACKAGE TYPES O1 O2 VSS NU O3 O4 O5 FEATURES 28 27 26 25 24 23 22 21 20 19 18 17 16 15 VCC A14 A13 A8 A9 A11 OE A10 CE O7 O6 O5 O4 O3 The Microchip Technology Inc. 27C256 is a CMOS 256K bit electrically Programmable Read Only Memory (EPROM). The device is organized as 32K words by 8 bits (32K bytes). Accessing individual bytes from an address transition or from power-up (chip enable pin going low) is accomplished in less than 90 ns. This very high speed device allows the most sophisticated microprocessors to run at full speed without the need for WAIT states. CMOS design and processing enables this part to be used in systems where reduced power consumption and reliability are requirements. A complete family of packages is offered to provide the most flexibility in applications. For surface mount applications, PLCC, or SOIC packaging is available. Tape and reel packaging is also available for PLCC or SOIC packages. 2004 Microchip Technology Inc. DS11001N-page 1 27C256 1.0 ELECTRICAL CHARACTERISTICS 1.1 Maximum Ratings* TABLE 1-1: PIN FUNCTION TABLE Name Function VCC and input voltages w.r.t. VSS ........ -0.6V to +7.25V A0-A14 VPP voltage w.r.t. VSS during programming ....................................... -0.6V to +14.0V CE Chip Enable OE Output Enable Output voltage w.r.t. VSS ................-0.6V to VCC +1.0V VPP Programming Voltage Storage temperature ..........................-65°C to +150°C O0 - O7 Ambient temp. with power applied .....-65°C to +125°C VCC +5V Power Supply *Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. VSS Ground NC No Connection; No Internal Connection NU Not Used; No External Connection Is Allowed Voltage on A9 w.r.t. VSS ...................... -0.6V to +13.5V TABLE 1-2: Address Inputs Data Output READ OPERATION DC CHARACTERISTICS VCC = +5V (±10%) Commercial: Industrial: Extended (Automotive): Parameter Tamb = 0°C to +70°C Tamb = -40°C to +85°C Tamb = -40°C to +125°C Part* Status Symbol Min. Max. Units Conditions Input Voltages all Logic "1" Logic "0" VIH VIL 2.0 -0.5 VCC+1 0.8 V V Input Leakage all — ILI -10 10 µA VIN = 0 to VCC Output Voltages all Logic "1" Logic "0" VOH VOL 2.4 0.45 V V IOH = -400 µA IOL = 2.1 mA Output Leakage all — ILO -10 10 µA VOUT = 0V to VCC Input Capacitance all — CIN — 6 pF VIN = 0V; Tamb = 25°C; f = 1 MHz Output Capacitance all — COUT — 12 pF VOUT = 0V; Tamb = 25°C; f = 1 MHz Power Supply Current, Active C I,E TTL input TTL input ICC1 ICC2 — — 20 25 mA mA VCC = 5.5V; VPP = VCC f = 1 MHz; OE = CE = VIL; IOUT = 0 mA; VIL = -0.1 to 0.8V; VIH = 2.0 to VCC; Note 1 Power Supply Current, Standby C I, E all TTL input TTL input CMOS input ICC(S) — 2 3 100 mA mA µA all all Read Mode Read Mode IPP VPP 100 VCC µA V IPP Read Current VPP Read Voltage VCC-0.7 CE = VCC ± 0.2V VPP = 5.5V * Parts: C=Commercial Temperature Range; I, E=Industrial and Extended Temperature Ranges Note 1: Typical active current increases .75 mA per MHz up to operating frequency for all temperature ranges. DS11001N-page 2 2004 Microchip Technology Inc. 27C256 TABLE 1-3: READ OPERATION AC CHARACTERISTICS AC Testing Waveform: Output Load: Input Rise and Fall Times: Ambient Temperature: VIH = 2.4V and VIL = 0.45V; VOH = 2.0V VOL = 0.8V 1 TTL Load + 100 pF 10 ns Commercial: Tamb = 0°C to +70°C Industrial: Tamb = -40°C to +85°C Automotive: Tamb = -40°C to +125°C 27C256-90* 27C256-10* 27C256-12 27C256-15 27C256-20 Parameter Sym Units Conditions Min Max Min Max Min Max Min Max Min Max Address to Output Delay tACC — 90 — 100 — 120 — 150 — 200 ns CE=OE =VIL CE to Output Delay tCE — 90 — 100 — 120 — 150 — 200 ns OE = VIL OE to Output Delay tOE — 40 — 45 — 55 — 65 — 75 ns CE = VIL CE or OE to O/P High Impedance tOFF 0 30 0 30 0 35 0 50 0 55 ns Output Hold from Address CE or OE, whichever goes first tOH 0 — 0 — 0 — 0 — 0 — ns * -10, -90 AC Testing Waveform: VIH = 2.4V and VIL = .45V; VOH = 1.5V and VOL = 1.5V Output Load: 1 TTL Load + 30pF FIGURE 1-1: READ WAVEFORMS V IH Address Valid Address V IL V IH CE V IL t CE(2) V IH OE V IL Outputs O0 - O7 V OH t OFF(1,3) t OH t OE(2) High Z High Z Valid Output V OL t ACC Notes: (1) t OFF is specified for OE or CE, whichever occurs first (2) OE may be delayed up to t CE - t OE after the falling edge of CE without impact on t (3) This parameter is sampled and is not 100% tested. 2004 Microchip Technology Inc. CE DS11001N-page 3 27C256 TABLE 1-4: PROGRAMMING DC CHARACTERISTICS Ambient Temperature: Tamb = 25°C ± 5°C VCC = 6.5V ± 0.25V, VPP = VH = 13.0V ± 0.25V Parameter Status Symbol Min Max. Units Input Voltages Logic”1” Logic”0” VIH VIL 2.0 -0.1 VCC+1 0.8 V V Input Leakage — ILI -10 10 µA VIN = 0V to VCC Logic”1” Logic”0” VOH VOL 2.4 0.45 V V IOH = -400 µA IOL = 2.1 mA VCC Current, program & verify — ICC2 — 20 mA Note 1 VPP Current, program — IPP2 — 25 mA Note 1 A9 Product Identification — VH 11.5 12.5 V Output Voltages Conditions Note 1: VCC must be applied simultaneously or before VPP and removed simultaneously or after VPP TABLE 1-5: PROGRAMMING AC CHARACTERISTICS for Program, Program Verify and Program Inhibit Modes Parameter AC Testing Waveform: VIH=2.4V and VIL=0.45V; VOH=2.0V; VOL=0.8V Output Load: 1 TTL Load + 100pF Ambient Temperature: Tamb=25°C ± 5°C VCC= 6.5V ± 0.25V, VPP = VH = 13.0V ± 0.25V Symbol Min. Max. Units Address Set-Up Time tAS 2 — µs Data Set-Up Time tDS 2 — µs Data Hold Time tDH 2 — µs Address Hold Time tAH 0 — µs Float Delay (2) tDF 0 130 ns VCC Set-Up Time tVCS 2 — µs Program Pulse Width (1) tPW 95 105 µs CE Set-Up Time tCES 2 — µs OE Set-Up Time tOES 2 — µs VPP Set-Up Time tVPS 2 — µs Data Valid from OE tOE — 100 ns Remarks 100 µs typical Note 1: For express algorithm, initial programming width tolerance is 100 µs ±5%. 2: This parameter is only sampled and not 100% tested. Output float is defined as the point where data is no longer driven (see timing diagram). DS11001N-page 4 2004 Microchip Technology Inc. 27C256 FIGURE 1-2: PROGRAMMING WAVEFORMS Program Verify V IH Address Address Stable V IL t AS t AH V IH High Z Data Data Stable V IL t DS Data Out Valid t DF (1) t DH 13.0V(2) V PP t VPS 5.0V 6.5V(2) V CC t VCS 5.0V V IH CE V IL t OES t PW V IH OE t OE (1) V IL Notes: TABLE 1-6: (1) t DF and t OE are characteristics of the device but must be accommodated by the programmer (2) V CC = 6.5 V ±0.25V, V PP = V H = 13.0V ±0.25V for express algorithm MODES Operation Mode CE OE VPP A9 O0 - O7 Read VIL VIL VCC X DOUT Program VIL VIH VH X DIN Program Verify VIH VIL VH X DOUT Program Inhibit VIH VIH VH X High Z Standby VIH X VCC X High Z Output Disable VIL VIH VCC X High Z Identity VIL VIL VCC VH Identity Code X = Don’t Care 1.2 Read Mode (See Timing Diagrams and AC Characteristics) Read Mode is accessed when: a) b) For Read operations, if the addresses are stable, the address access time (tACC) is equal to the delay from CE to output (tCE). Data is transferred to the output after a delay from the falling edge of OE (tOE). the CE pin is low to power up (enable) the chip the OE pin is low to gate the data to the output pins 2004 Microchip Technology Inc. DS11001N-page 5 27C256 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 memory array. The memory matrix is erased to the all 1’s state when exposed to ultraviolet light. To ensure complete 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 ultraviolet lamp with a wavelength of 2537 Angstroms, intensity of 12,000µW/cm2 for approximately 20 minutes. 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) b) c) d) VCC is brought to the proper voltage, VPP is brought to the proper VH level, the OE pin is high, and the CE pin is low. 1.7 Verify After the array has been programmed it must be verified to ensure all the bits have been correctly programmed. This mode is entered when all the following conditions are met: VCC is at the proper level, VPP is at the proper VH level, the CE line is high, and the OE line is low. a) b) c) d) 1.8 Inhibit When programming multiple devices in parallel with different 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 Identity Manufacturer Device Type* Input Output H e x A0 0 O O O O O O O 7 6 5 4 3 2 1 0 VIL VIH 0 0 1 0 1 0 0 1 29 1 0 0 0 1 1 0 0 8C * Code subject to change 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 presented to pins O0-O7. When data and address are stable, a low going pulse on the CE line programs that location. DS11001N-page 6 2004 Microchip Technology Inc. 27C256 FIGURE 1-3: PROGRAMMING EXPRESS ALGORITHM Conditions: Tamb = 25•C ±5•C V CC = 6.5 ±0.25V V PP = 13.0 ±0.25V Start ADDR = First Location V CC = 6.5V V PP = 13.0V X=0 Program one 100 µs pulse Increment X Verify Byte Pass Fail No Yes X = 10 ? Last Address? Device Failed Yes No Increment Address V CC = V PP = 4.5V, 5.5V Device Passed 2004 Microchip Technology Inc. Yes All bytes = original data? No Device Failed DS11001N-page 7 27C256 27C256 Product Identification System To order or to obtain information (e.g., on pricing or delivery), please use listed part numbers, and refer to factory or listed sales offices. 27C256 – 90 I /TS Package: Temperature Range: Access Time: Device DS11001N-page 8 L = Plastic Leaded Chip Carrier P = Plastic DIP (Mil 600) SO = Plastic SOIC (Mil 300) Blank = 0°C to +70°C I = -40°C to +85°C E = -40°C to +125°C 90 10 12 15 20 27C256 = = = = = 90 ns 100 ns 120 ns 150 ns 200 ns 256K (32K x 8) CMOS EPROM 2004 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, PowerSmart, rfPIC, and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, SmartTel and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2004, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona and Mountain View, California in October 2003. The Company’s quality system processes and procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. 2004 Microchip Technology Inc. DS11001N-page 9 WORLDWIDE SALES AND SERVICE AMERICAS China - Beijing Singapore Corporate Office Unit 706B Wan Tai Bei Hai Bldg. No. 6 Chaoyangmen Bei Str. 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