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SST49LF020A

2 Mbit LPC Flash

Silicon Storage Technology 

Data Sheet

DESIGN CONSIDERATIONS

SST recommends a high frequency 0.1 µF ceramic capac-

itor to be placed as close as possible between VDD and

VSS less than 1 cm away from the VDD pin of the device.

Additionally, a low frequency 4.7 µF electrolytic capacitor

from VDD to VSS should be placed within 5 cm of the VDD

pin. If you use a socket for programming purposes add an

additional 1-10 µF next to each socket.

PRODUCT IDENTIFICATION

The Product Identification mode identifies the device as the

SST49LF020A and manufacturer as SST.

TABLE 2: Product Identification

Manufacturer’s ID

Device ID

SST49LF020A

Address

0000H

0001H

Data

BFH

52H

T2.2 1206

MODE SELECTION

The SST49LF020A flash memory devices can operate in

two distinct interface modes: the LPC mode and the Parallel

Programming (PP) mode. The mode pin is used to set the

interface mode selection. If the mode pin is set to logic High,

the device is in PP mode. If the mode pin is set Low, the

device is in the LPC mode. The mode selection pin must be

configured prior to device operation. The mode pin is inter-

nally pulled down if the pin is left unconnected. In LPC

mode, the device is configured to its host using standard

LPC interface protocol. Communication between Host and

the SST49LF020A occurs via the 4-bit I/O communication

signals, LAD [3:0] and LFRAME#. In PP mode, the device

is programmed via an 11-bit address and an 8-bit data I/O

parallel signals. The address inputs are multiplexed in row

and column selected by control signal R/C# pin. The row

addresses are mapped to the lower internal addresses

(A10-0), and the column addresses are mapped to the

higher internal addresses (AMS-11). See Figure 4, the

Device Memory Map, for address assignments.

2 Mbit LPC Flash

SST49LF020A

LPC MODE

Device Operation

The LPC mode uses a 5-signal communication interface, a

4-bit address/data bus, LAD[3:0], and a control line,

LFRAME#, to control operations of the SST49LF020A.

Cycle type operations such as Memory Read and Memory

Write are defined in Intel Low Pin Count Interface Specifi-

cation, Revision 1.0. JEDEC Standard SDP (Software

Data Protection) Program and Erase commands

sequences are incorporated into the standard LPC mem-

ory cycles. See Figures 7 through 12 for command

sequences.

LPC signals are transmitted via the 4-bit Address/Data bus

(LAD[3:0]), and follow a particular sequence, depending on

whether they are Read or Write operations. LPC memory

Read and Write cycle is defined in Tables 5 and 6.

Both LPC Read and Write operations start in a similar way

as shown in Figures 5 and 6. The host (which is the term

used here to describe the device driving the memory)

asserts LFRAME# for one or more clocks and drives a start

value on the LAD[3:0] bus.

At the beginning of an operation, the host may hold the

LFRAME# active for several clock cycles, and even change

the Start value. The LAD[3:0] bus is latched every rising

edge of the clock. On the cycle in which LFRAME# goes

inactive, the last latched value is taken as the Start value.

CE# must be asserted one cycle before the start cycle to

select the SST49LF020A for Read and Write operations.

Once the SST49LF020A identify the operation as valid (a

start value of all zeros), it next expects a nibble that indi-

cates whether this is a memory Read or Write cycle. Once

this is received, the device is now ready for the Address

cycles. The LPC protocol supports a 32-bit address phase.

The SST49LF020A encode ID and register space access

in the address field. See Table 3 for address bits definition.

For Write operation the Data cycle will follow the Address

cycle, and for Read operation TAR and SYNC cycles occur

between the Address and Data cycles. At the end of every

operation, the control of the bus must be returned to the

host by a 2-clock TAR cycle.

TABLE 3: Address bits definition

A31: A23

1111 1111 1b

A22

1 = Memory Access

0 = Register access

1. See Table 7 for multiple device selection configuration.

A21: A18

ID[3:0]1

A17:A0

Device Memory address

T3.0 1206

©2006 Silicon Storage Technology, Inc.

10

S71206-08-000

5/06

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