®
AS7C33512PFS32A
AS7C33512PFS36A
12/23/04, v 2.6 Alliance Semiconductor 4 of 19
Functional description
The AS7C33512PFS32A/36A is a high-performance CMOS 16-Mbit synchronous Static Random Access Memory (SRAM) device
organized as 524,288 words x 32/36. It incorporates a two-stage register-register pipeline for highest frequency on any given technology.
Fast cycle times of 6/7.5 ns with clock access times (t
CD
) of 3.4/3.8 ns enable 166, and 133 MHz bus frequencies. Three chip enable (CE)
inputs permit easy memory expansion. Burst operation is initiated in one of two ways: the controller address strobe (ADSC
), or the processor
address strobe (ADSP
). The burst advance pin (ADV) allows subsequent internally generated burst addresses.
Read cycles are initiated with ADSP
(regardless of WE and ADSC) using the new external address clocked into the on-chip address register
when ADSP
is sampled low, the chip enables are sampled active, and the output buffer is enabled with OE. In a read operation, the data
accessed by the current address registered in the address registers by the positive edge of CLK are carried to the data-out registers and driven
on the output pins on the next positive edge of CLK. ADV is ignored on the clock edge that samples ADSP asserted, but is sampled on all
subsequent clock edges. Address is incremented internally for the next access of the burst when ADV
is sampled low and both address
strobes are high. Burst mode is selectable with the
LBO
input. With
LBO
unconnected or driven high, burst operations use an interleaved
count sequence. With
LBO
driven low, the device uses a linear count sequence.
Write cycles are performed by disabling the output buffers with OE and asserting a write command. A global write enable GWE writes all 32/
36 regardless of the state of individual BW[a:d] inputs. Alternately, when GWE is high, one or more bytes may be written by asserting BWE
and the appropriate individual byte BWn signals.
BWn
is ignored on the clock edge that samples ADSP low, but it is sampled on all subsequent clock edges. Output buffers are disabled when
BWn
is sampled lOW regardless of OE. Data is clocked into the data input register when BWn is sampled low. Address is incremented
internally to the next burst address if BWn and ADV are sampled low. This device operates in single-cycle deselect feature during read
cycles.
Read or write cycles may also be initiated with ADSC instead of ADSP. The differences between cycles initiated with ADSC and ADSP are
as follows:
•ADSP
must be sampled high when ADSC is sampled low to initiate a cycle with ADSC.
•WE signals are sampled on the clock edge that samples ADSC low (and ADSP high).
• Master chip enable CE0 blocks ADSP, but not ADSC.
The AS7C33512PFS32A/36A family operates from a core 3.3V power supply. I/Os use a separate power supply that can operate at 2.5V or
3.3V. These devices are available in a 100-pin TQFP package.
TQFP capacitance
* Guaranteed not tested
TQFP thermal resistance
Parameter Symbol Test conditions Min Max Unit
Input capacitance C
IN
*
V
IN
= 0V - 5 pF
I/O capacitance C
I/O
*
V
OUT
= 0V - 7 pF
Description Conditions Symbol Typical Units
Thermal resistance
(junction to ambient)
1
1 This parameter is sampled
Test conditions follow standard test methods
and procedures for measuring thermal
impedance, per EIA/JESD51
1–layer θ
JA
40 °C/W
4–layer θ
JA
22 °C/W
Thermal resistance
(junction to top of case)
1
θ
JC
8 °C/W
