
A49FL004
PRELIMINARY       (September, 2005, Version 0.0) 
9 
AMIC Technology, Corp.
LPC MODE SELECTION 
The A49FL004 can operate in two configurable interfaces: 
The In-System Hardware interface and Address/Address 
Multiplexed (A/A Mux) interface controlled by IC pin. If the IC 
pin is set to logic high (V
IH
), the devices enter into A/A Mux 
interface mode. If the IC pin is set logic low (V
IL
), the devices 
will be in in-system hardware interface mode. During the in-
system hardware interface mode, the devices can 
automatically detect the Firmware Hub (FWH) or Low Pin 
Count (LPC) memory cycle sent from host system and 
response to the command accordingly. The IC pin must be 
setup during power-up or system reset, and stays no change 
during device operation. 
When working in-system, typically on a PC or Notebook for 
non Intel Platform, the A49FL004 is connected to the host 
system through a 5-pin communication interface operated 
based on a 33-MHz synchronous clock. The 5-pin interface is 
defined as LAD[3:0] and 
LFRAME
 pins under LPC mode for 
easy understanding as to those existing compatible products. 
When 
working 
off-system, 
Programmer, the device is operated through 11-pin 
multiplexed address - A[10:0] and 8-pin data I/O - I/O[7:0] 
interfaces. The memory addresses of device are input 
through two bus cycles as row and column addresses 
controlled by a 
C
R/
pin. 
typically 
on 
a 
EPROM 
LPC MODE OPERATION 
In LPC mode, the A49FL004 is connected through a 5-pin 
communication interface - LAD[3:0] and 
LFRAME
  pins to 
work with non Intel Family of South Bridge chipset 
platforms. The LPC mode also supports JEDEC standard 
Software Data Protection (SDP) product ID entry, byte 
program, sector erase, and block erase command sequences. 
The chip erase command sequence is only available in A/A 
Mux mode.  
The addresses and data are transmitted through the 4-bit 
LAD[3:0] bus synchronized with the input clock on CLK pin 
during a LAD memory cycle operation. The address or data 
on LAD[3:0] bus is latched on the rising edge of the clock. 
The pulse of 
LFRAME
 pin is inserted for one clock indicates 
the start of a LPC memory read or memory write cycle. The 
address or data on LAD[3:0] is latched on the rising edge of 
CLK. The device enters standby mode when 
LFRAME
 is 
high and no internal operation is in progress. The device is in 
ready mode when 
LFRAME
  is low and no activity is on the 
LPC bus. 
LPC Mode Memory Read/Write Operation  
In LPC mode, the A49FL004 uses the 5-pin LPC interface 
includes 4-bit LAD[3:0] and LFRAME pins to communicate 
with the host system. The addresses and data are 
transmitted through the 4-bit LAD[3:0] bus synchronized with 
the input clock on CLK pin during a LPC memory cycle 
operation. The address or data on LAD[3:0] bus is latched on 
the rising edge of the clock. The pulse of LFRAME signal 
inserted for one or more clocks indicates the start of a LPC 
memory read or write cycle. 
Once the LPC memory cycle is started, asserted by 
LFRAME , a START value “0000b” is expected by the device 
as a valid command cycle.  
Then a CYCTYPE + DIR value (“010xb” for memory read 
cycle or “011xb” for memory write cycle) is used to indicates 
the type of memory cycle. Refer to Table 4 and 5 for LPC 
Memory Read and Write Cycle Definition. 
There are 8 clock fields in a LPC memory cycle that gives a 
32 bit memory address A31 - A0 through LAD[3:0] with the 
most-significant nibble first. The memory space of A49FL004 
is mapped directly to top of 4 Gbyte system memory space. 
See Figure 8 for System Memory Map. 
The A49FL004 is mapped to the address location of 
(FFFFFFFFh - FFF80000h), the A31- A19 must be loaded 
with “1” to select and activate the device during a LPC 
memory operation. Only A18 - A0 is used to decode and 
access the 512 KByte memory. 
LPC Abort Operation 
The 
LFRAME
  is driven low for one or more clock cycles 
during a LPC cycle, the cycle will be terminated and the 
device will wait for the ABORT command. The host may drive 
the LAD[3:0] with “1111b” (ABORT command) to return the 
device to the ready mode. If abort occurs during a Write 
operation such as checking the operation status  with 
Data
Polling (I/O
7
) or Toggle Bit (I/O
6
) pins, the read status 
cycle will be aborted but the internal program or erase 
operation will not be affected. In this case, only the reset 
operation initiated by 
RST
  or INIT pin can terminate the 
write operation. 
Response TO Invalid Fields 
During LPC operations, the A49FL004 will not explicitly 
indicate that it has received invalid field sequences. The 
responses to specific invalid fields or sequence is as follows: 
Address out of range:
 The A49FL004 will only response to 
address range as specified in Table 9. Address A22 has the 
special function of directing reads and writes to the flash 
memory (A22=1) or to the register space (A22=0). 
ID mismatch:
 The A49FL004 will compare ID bits in the 
address field with the hardware strapping. If there is a 
mismatch, the device will ignore the cycle.