27256 EPROM

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M27C256B256 Kbit (32Kb 8) UV EPROM and OTP EPROMFeature summary

5V 10% supply voltage in Read operation Access time: 45ns Low power consumption: Active Current 30mA at 5MHz Standby Current 100A Programming voltage: 12.75V 0.25V Programming time: 100s/Word Electronic signature Manufacturer Code: 20h Device Code: 8Dh ECOPACK packages available PDIP28 (B)2828

1

FDIP28W (F)

1

PLCC32 (C)

May 2006

Rev 2

1/24www.st.com 1

Contents

M27C256B

Contents1 2 Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Device operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 Read mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Two-line output control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 System considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 PRESTO II programming algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Program inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Program Verify . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Electronic signature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Erasure operation (applies for UV EPROM) . . . . . . . . . . . . . . . . . . . . . . . 11

3 4 5 6 7

Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Package mechanical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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M27C256B

List of tables

List of tablesTable 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Electronic signature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 AC measurement conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Read mode DC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Programming mode DC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Read mode AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Read mode AC characteristics 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Programming mode AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 FDIP28WB - 28 pin Ceramic Frit-seal DIP, with window (round 0.280"), package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 PDIP28 - 28 pin Plastic DIP, 600 mils width, package mechanical data . . . . . . . . . . . . . . 20 PLCC32 - 32 pin Rectangular Plastic Leaded Chip Carrier, package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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List of figures

M27C256B

List of figuresFigure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 DIP connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 LCC connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Programming flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 AC testing input output waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 AC testing load circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Read mode AC waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Programming and Verify modes AC waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 FDIP28WB - 28 pin Ceramic Frit-seal DIP, with window, package outline . . . . . . . . . . . . . 19 PDIP28 - 28 pin Plastic DIP, 600 mils width, package outline . . . . . . . . . . . . . . . . . . . . . . 20 PLCC32 - 32 pin Rectangular Plastic Leaded Chip Carrier, package outline. . . . . . . . . . . 21

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M27C256B

Summary description

1

Summary descriptionThe M27C256B is a 256 Kbit EPROM offered in the two ranges UV (ultra violet erase) and OTP (one time programmable). It is ideally suited for microprocessor systems and is organized as 32,768 by 8 bits. The FDIP28W (window ceramic frit-seal package) has a transparent lid which 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 programming procedure. For applications where the content is programmed only one time and erasure is not required, the M27C256B is offered in PDIP28 and PLCC32 packages. In order to meet environmental requirements, ST offers the M27C256B in ECOPACK packages. ECOPACK packages are Lead-free. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. Figure 1. Logic diagramVCC VPP

15 A0-A14

8 Q0-Q7

E G

M27C256B

VSSAI00755B

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Summary description Table 1.A0-A14 Q0-Q7 E G VPP VCC VSS NC DU

M27C256B Signal namesAddress Inputs Data Outputs Chip Enable Output Enable Program Supply Supply Voltage Ground Not Connected Internally Dont Use

Figure 2.

DIP connectionsVPP A12 A7 A6 A5 A4 A3 A2 A1 A0 Q0 Q1 Q2 VSS 1 28 2 27 3 26 4 25 5 24 6 23 7 22 M27C256B 8 21 9 20 10 19 11 18 12 17 13 16 14 15AI00756

VCC A14 A13 A8 A9 A11 G A10 E Q7 Q6 Q5 Q4 Q3

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M27C256B Figure 3. LCC connectionsA7 A12 VPP DU VCC A14 A13

Summary description

1 32 A6 A5 A4 A3 A2 A1 A0 NC Q0 A8 A9 A11 NC G A10 E Q7 Q6

9

M27C256B

25

17 Q1 Q2 VSS DU Q3 Q4 Q5AI00757

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Device operation

M27C256B

2

Device operationThe operating modes of the M27C256B are listed in the Operating Modes. A single power supply is required in the read mode. All inputs are TTL levels except for VPP and 12V on A9 for Electronic Signature.

2.1

Read modeThe M27C256B has two control functions, both of which must be logically active in order to obtain data at the outputs. Chip Enable (E) is the power control and should be used for device selection. Output Enable (G) is the output control and should be used to gate data to the output pins, independent of device selection. Assuming that the addresses are stable, the address access time (tAVQV) is equal to the delay from E to output (tELQV). Data is available at the output after delay of tGLQV from the falling edge of G, assuming that E has been low and the addresses have been stable for at least tAVQV-tGLQV.

2.2

Standby modeThe M27C256B has a standby mode which reduces the supply current from 30mA to 100A. The M27C256B is placed in the standby mode by applying a CMOS high signal to the E input. When in the standby mode, the outputs are in a high impedance state, independent of the G input.

2.3

Two-line output controlBecause EPROMs are usually used in larger memory arrays, this product features a 2 line control function which accommodates the use of multiple memory connection. The two line control function allows:

the lowest possible memory power dissipation, complete assurance that output bus contention will not occur.

For the most efficient use of these two control lines, E should be decoded and used as the primary device selecting function, while G should be made a common connection to all devic