CY7C0853V-100BBC Cypress Semiconductor Corp, CY7C0853V-100BBC Datasheet - Page 8

• Manufacturer Part Number: CY7C0853V-100BBC
• Description: IC,SYNC SRAM,256KX36,CMOS,BGA,172PIN,PLASTIC
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY7C0853V-100BBC

• Format - Memory: RAM
• Memory Type: SRAM - Dual Port, Synchronous
• Memory Size: 9M (256K x 36)
• Speed: 100MHz
• Interface: Parallel
• Voltage - Supply: 3.135 V ~ 3.465 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 172-LFBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Document #: 38-06070 Rev. *D
Address Counter and Mask Register
Operations
This
CY7C0850V/CY7C0851V/CY7C0852V devices, but not to
CY7C0853 device. Each port of these devices has a program-
mable burst address counter. The burst counter contains three
registers: a counter register, a mask register, and a mirror
register.
The counter register contains the address used to access the
RAM array. It is changed only by the Counter Load, Increment,
Counter Reset, and by master reset (MRST) operations.
The mask register value affects the Increment and Counter
Reset operations by preventing the corresponding bits of the
counter register from changing. It also affects the counter
interrupt output (CNTINT). The mask register is changed only
by the Mask Load and Mask Reset operations, and by the
MRST. The mask register defines the counting range of the
counter register. It divides the counter register into two
regions: zero or more “0s” in the most significant bits define
the masked region, one or more “1s” in the least significant bits
define the unmasked region. Bit 0 may also be “0,” masking
the least significant counter bit and causing the counter to
increment by two instead of one.
The mirror register is used to reload the counter register on
increment operations (see “retransmit,” below). It always
contains the value last loaded into the counter register, and is
changed only by the Counter Load, and Counter Reset opera-
tions, and by the MRST.
Table 3 summarizes the operation of these registers and the
required input control signals. The MRST control signal is
asynchronous. All the other control signals in Table 3
(CNT/MSK, CNTRST, ADS, CNTEN) are synchronized to the
port’s CLK. All these counter and mask operations are
independent of the port’s chip enable inputs (CE0 and CE1).
Counter enable (CNTEN) inputs are provided to stall the
operation of the address input and utilize the internal address
generated by the internal counter for fast, interleaved memory
applications. A port’s burst counter is loaded when the port’s
address strobe (ADS) and CNTEN signals are LOW. When the
port’s CNTEN is asserted and the ADS is deasserted, the
address counter will increment on each LOW to HIGH
transition of that port’s clock signal. This will Read/Write one
word from/into each successive address location until CNTEN
is deasserted. The counter can address the entire memory
array, and will loop back to the start. Counter reset (CNTRST)
is used to reset the unmasked portion of the burst counter to
0s. A counter-mask register is used to control the counter
wrap.
Counter Reset Operation
All unmasked bits of the counter and mirror registers are reset
to “0.” All masked bits remain unchanged. A Mask Reset
followed by a Counter Reset will reset the counter and mirror
registers to 00000, as will master reset (MRST).
Notes:
10. This section describes the CY7C0852V, which have 17 address bits and a maximum address value of 1FFFF. The CY7C0851V has 16 address bits, register
11. CNTINT and CNTRST specs are guaranteed by design to operate properly at speed grade operating frequency when tied together.
lengths of 16 bits, and a maximum address value of FFFF. The CY7C0850V has 15 address bits, register lengths of 15 bits, and a maximum address value of 7FFF
section
[10]
describes
the
features
only
apply
to
Counter Load Operation
The address counter and mirror registers are both loaded with
the address value presented at the address lines.
Counter Readback Operation
The internal value of the counter register can be read out on
the address lines. Readback is pipelined; the address will be
valid t
address readback occurs while the port is enabled (CE0 LOW
and CE1 HIGH), the data lines (DQs) will be three-stated.
Figure 1 shows a block diagram of the operation.
Counter Increment Operation
Once the address counter register is initially loaded with an
external address, the counter can internally increment the
address value, potentially addressing the entire memory array.
Only the unmasked bits of the counter register are incre-
mented. The corresponding bit in the mask register must be
a “1” for a counter bit to change. The counter register is incre-
mented by 1 if the least significant bit is unmasked, and by 2
if it is masked. If all unmasked bits are “1,” the next increment
will wrap the counter back to the initially loaded value. If an
Increment results in all the unmasked bits of the counter being
“1s,” a counter interrupt flag (CNTINT) is asserted. The next
Increment will return the counter register to its initial value,
which was stored in the mirror register. The counter address
can instead be forced to loop to 00000 by externally
connecting CNTINT to CNTRST.
in one or more of the unmasked bits of the counter being “0”
will de-assert the counter interrupt flag. The example in
Figure 2 shows the counter mask register loaded with a mask
value of 0003Fh unmasking the first 6 bits with bit “0” as the
LSB and bit “16” as the MSB. The maximum value the mask
register can be loaded with is 1FFFFh. Setting the mask
register to this value allows the counter to access the entire
memory space. The address counter is then loaded with an
initial value of 8h. The base address bits (in this case, the 6th
address through the 16th address) are loaded with an address
value but do not increment once the counter is configured for
increment operation. The counter address will start at address
8h. The counter will increment its internal address value till it
reaches the mask register value of 3Fh. The counter wraps
around the memory block to location 8h at the next count.
CNTINT is issued when the counter reaches its maximum
value.
Counter Hold Operation
The value of all three registers can be constantly maintained
unchanged for an unlimited number of clock cycles. Such
operation is useful in applications where wait states are
needed, or when address is available a few cycles ahead of
data in a shared bus interface.
CA2
after the next rising edge of the port’s clock. If
CY7C0850V/CY7C0851V
CY7C0852V/CY7C0853V
[11]
An increment that results
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