Rainbow Electronics W29C020C User Manual

W29C020C

256K x 8 CMOS FLASH MEMORY

GENERAL DESCRIPTION

The W29C020C is a 2-megabit, 5-volt only CMOS flash memory organized as 256K × 8 bits. The device can be written (erased and programmed) in-system with a standard 5V power supply. A 12-volt VPP is not required. The unique cell architecture of the W29C020C results in fast write (erase/program) operations with extremely low current consumption compared to other comparable 5-volt flash memory products. The device can also be written (erased and programmed) by using standard EPROM programmers.

FEATURES

• Single 5-volt write (erase and program)

operations

• Fast page-write operations

− 128 bytes per page

− Page write (erase/program) cycle: 10 mS

(max.)

− Effective by te-write (erase/program) cycle time: 39 µS

− Optional software-protected data write

• Fast chip-erase operation: 50 mS

• Two 8 KB boot blocks with lockout

• Whole chip cycling:

10K (typ.)

• Read access time: 70/90/120 nS

• Twenty-year data retention

• Software and hardware data protection

• Low power consumption

− Active current: 25 mA (typ.)

− Standby current: 20 µA (typ.)

• Automatic write (erase/program) timing with

internal VPP generation

• End of write (erase/program) detection

− Toggle bit

− Data polling

• Latched address and data

• All inputs and outputs directly TTL compatible

• JEDEC standard byte-wide pinouts

• Available packages: 32-pin 600 mil DIP, 32-pin

TSOP, and 32-pin PLCC

Publication Release Date: April 1999

- 1 - Revision A1

PIN CONFIGURATIONS BLOCK DIAGRAM

123

910111213

1415163231

45678

ARRAY

CONTROL

BUFFER

WEA0A17

W29C020C

A16

A15

A12

A5 A4 A3 A2 A1 A0

DQ0 DQ1 DQ2 GND

A7 A6 A5 A4 A3 A2 A1 A0

DQ0

A11

A8 A13 A14 A17

A16

A15

A12

16 A3

32-pin

DIP

16N

5 6 7 8

32-pin PLCC

9 10 11 12 13

32-pin TSOP

A17

A14

A13

A11

A10

DQ7

DQ6

DQ5

DQ4

DQ3

1 7

3031321234

A14

A13

A11

A10

DQ7

20191817161514

OUTPUT

DQ0

DQ7

8K Byte Boot Block (Optional)

. .

DECODER

CORE

8K Byte Boot Block (Optional)

PIN DESCRIPTION

SYMBOL PIN NAME

A0−A17 Address Inputs

A10

DQ7

DQ6

DQ5

DQ4

DQ3

GND

DQ2

DQ1

DQ0

18 17

DQ0−DQ7 Data Inputs/Outputs

Chip Enable Output Enable Write Enable

VDD Power Supply

GND Ground

NC No Connection

- 2 -

W29C020C

FUNCTIONAL DESCRIPTION

Read Mode

The read operation of the W29C020C is controlled by CE and OE , both of which have to be low for the host to obtain data from the outputs. CE is used for device selection. When CE is high, the chip is deselected and only standby power will be consumed. OE is the output control and is used to gate data from the output pins. The data bus is in high impedance state when either CE or OE is high.

Refer to the read cycle timing waveforms for further details.

Page Write Mode

The W29C020C is written (erased/programmed) on a page basis. Every page contains 128 bytes of data. If a byte of data within a page is to be changed, data for the entire page must be loaded into the device. Any byte that is not loaded will be erased to "FF hex" during the write operation of the page.

The write operation is initiated by forcing CE and WE low and OE high. The write procedure consists of two steps. Step 1 is the byte-load cycle, in which the host writes to the page buffer of the device.

Step 2 is an internal write (erase/program) cycle, during which the data in the page buffers are simultaneously written into the memory array for non-volatile storage.

During the byte-load cycle, the addresses are latched by the falling edge of either CE or WE, whichever occurs last. The data are latched by the rising edge of either CE or WE, whichever occurs

first. If the host loads a second byte into the page buffer within a byte-load cycle time (TBLC ) of 200 µS after the initial byte-load cycle, the W29C020C will stay in the page load cycle. Additional bytes can then be loaded consecutively. The page load cycle will be terminated and the internal write (erase/program) cycle will start if no additional byte is loaded into the page buffer A7 to A17 specify the page address. All bytes that are loaded into the page buffer must have the same page address. A0 to A6 specify the byte address within the page. The bytes may be loaded in any order; sequential loading is not required.

In the internal write cycle, all data in the page buffers, i.e., 128 bytes of data, are written simultaneously into the memory array. Before the completion of the internal write cycle, the host is free to perform other tasks such as fetching data from other locations in the system to prepare to write the next page.

Software-protected Data Write

The device provides a JEDEC-approved optional software-protected data write. Once this scheme is enabled, any write operation requires a three-byte command sequence (with specific data to a specific address) to be performed before the data load operation. The three-byte load command sequence begins the page load cycle, without which the write operation will not be activated. This write scheme provides optimal protection against inadvertent write cycles, such as cycles triggered by noise during system power-up and power-down.

The W29C020C is shipped with the software data protection enabled. To enable the software data protection scheme, perform the three-byte command cycle at the beginning of a page load cycle. The device will then enter the software data protection mode, and any subsequent write operation must be preceded by the three-byte command sequence cycle. Once enabled, the software data protection will remain enabled unless the disable commands are issued. A power transition will not reset the software data protection feature. To reset the device to unprotected mode, a six-byte command sequence is required. For information about specific codes, see the Command Codes for Software Data Protection in the Table of Operating Modes. For information about timing waveforms, see the timing diagrams below.

- 3 -

W29C020C

Hardware Data Protection

The integrity of the data stored in the W29C020C is also hardware protected in the following ways: (1) Noise/Glitch Protection: A WE pulse of less than 15 nS in duration will not initiate a write cycle.

(2) VDD Power Up/Down Detection: The write operation is inhibited when VDD is less than 2.5V. (3) Write Inhibit Mode: Forcing OE low, CE high, or WE high will inhibit the write operation. This

prevents inadvertent writes during power-up or power-down periods.

(4) VDD power-on delay: When VDD reaches its sense level, the device will automatically timeout for

5 mS before any write (erase/program) operation.

Chip Erase Modes

The entire device can be erased by using a six-byte software command code. See the Software Chip Erase Timing Diagram.

Boot Block Operation

There are two boot blocks (8K bytes each) in this device, which can be used to store boot code. One of them is located in the first 8K bytes and the other is located in the last 8K bytes of the memory. The first 8K or last 8K of the memory can be set as a boot block by using a seven-byte command sequence.

See Command Codes for Boot Block Lockout Enable for the specific code. Once this feature is set the data for the designated block cannot be erased or programmed (programming lockout); other memory locations can be changed by the regular programming method. Once the boot block programming lockout feature is activated, the chip erase function will be disabled. In order to detect whether the boot block feature is set on the two 8K blocks, users can perform a six-byte command sequence: enter the product identification mode (see Command Codes for Identification/Boot Block Lockout Detection for specific code), and then read from address "00002 hex" (for the first 8K bytes) or "3FFF2 hex" (for the last 8K bytes). If the output data is "FF hex," the boot block programming lockout feature is activated; if the output data is "FE hex," the lockout feature is deactivated and the block can be programmed.

To return to normal operation, perform a three-byte command sequence to exit the identification mode. For the specific code, see Command Codes for Identification/Boot Block Lockout Detection.

Data Polling (DQ7)- Write Status Detection

The W29C020C includes a data polling feature to indicate the end of a write cycle. When the W29C020C is in the internal write cycle, any attempt to read DQ7 from the last byte loaded during the page/byteload cycle will receive the complement of the true data. Once the write cycle is completed. DQ7 will

show the true data. See the DATA Polling Timing Diagram.

- 4 -

W29C020C

CEOEWE

Toggle Bit (DQ6)- Write Status Detection

In addition to data polling, the W29C020C provides another method for determining the end of a write cycle. During the internal write cycle, any consecutive attempts to read DQ6 will produce alternating 0's and 1's. When the write cycle is completed, this toggling between 0's and 1's will stop. The device is then ready for the next operation. See Toggle Bit Timing Diagram.

Product Identification

The product ID operation outputs the manufacturer code and device code. The programming equipment automatically matches the device with its proper erase and programming algorithms.

The manufacturer and device codes can be accessed through software or by hardware operation. In the software access mode, a six-byte command sequence can be used to access the product ID. A read from address "00000 hex" outputs the manufacturer code "DA hex." A read from address "00001 hex" outputs the device code "45 hex." The product ID operation can be terminated by a three-byte command sequence.

In the hardware access mode, access to the product ID is activated by forcing CE and OE low, WE high, and raising A9 to 12 volts.

TABLE OF OPERATING MODES

Operating Mode Selection

Operating Range: 0 to 70° C (Ambient Temperature), VDD = 5V ±10%, VSS = 0V, VHH = 12V

MODE PINS

ADDRESS DQ.

Read VIL VIL VIH AIN Dout Write VIL VIH VIL AIN Din Standby VIH X X X High Z Write Inhibit X VIL X X High Z/DOUT

X X VIH X High Z/DOUT Output Disable X VIH X X High Z Product ID VIL VIL VIH A0 = VIL; A1−A17 = VIL;

A9 = VHH

VIL VIL VIH A0 = VIH; A1−A17 = VIL;

A9 = VHH

Manufacturer Code DA (Hex)

Device Code 45 (Hex)

Publication Release Date: April 1999

- 5 - Revision A1

W29C020C

address 5555

of page data

Pause 10 mS

Exit

Pause 10 mS

Exit

Command Codes for Software Data Protection

BYTE SEQUENCE TO ENABLE PROTECTION TO DISABLE PROTECTION

ADDRESS DATA ADDRESS DATA

0 Write 5555H AAH 5555H AAH 1 Write 2AAAH 55H 2AAAH 55H 2 Write 5555H A0H 5555H 80H 3 Write - - 5555H AAH 4 Write - - 2AAAH 55H 5 Write - - 5555H 20H

Software Data Protection Acquisition Flow

(Optional page-load

operation)

Software Data Protection Enable Flow

Load data AA

Load data 55

address 2AAA

Load data A0

address 5555

Sequentially load

up to 128 bytes

Software Data Protection Disable Flow

Load data AA

address 5555

Load data 55

address 2AAA

Load data 80

address 5555

Load data AA

Load data 55

address 2AAA

Load data 20

Notes for software program code: Data Format: DQ7−DQ0 (Hex) Address Format: A14−A0 (Hex)

- 6 -

Command Codes for Software Chip Erase

BYTE SEQUENCE ADDRESS DATA

0 Write 5555H AAH 1 Write 2AAAH 55H 2 Write 5555H 80H 3 Write 5555H AAH 4 Write 2AAAH 55H 5 Write 5555H 10H

Software Chip Erase Acquisition Flow

Load data AA

address 5555

Load data 55

address 2AAA

W29C020C

Notes for software chip erase: Data Format: DQ7−DQ0 (Hex) Address Format: A14−A0 (Hex)

Load data 80

address 5555

Load data AA

address 5555

Load data 55

address 2AAA

Load data 10

address 5555

Pause 50 mS

Exit

Publication Release Date: April 1999

- 7 - Revision A1

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Rainbow Electronics W29C020C User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual