7
4Mb: 256K x 18, 128K x 32/36 Flow-Through ZBT SRAM Micron Technology, Inc., reserves the right to change products or specifications without notice.
MT55L256L18F1_C.p65 – Rev. 6/01 ©2001, Micron Technology, Inc.
4Mb: 256K x 18, 128K x 32/36
FLOW-THROUGH ZBT SRAM
PRELIMINARY
TQFP PIN DESCRIPTIONS (continued)
x18 x32/x36 SYMBOL TYPE DESCRIPTION
88 88 R/W# Input Read/Write: This input determines the cycle type when
ADV/LD# is LOW and the only means for determining
READs and WRITEs. READ cycles may not be converted into
WRITEs (and vice versa) other than by loading a new
address. A LOW on this pin permits BYTE WRITE opera-
tions and must meet the setup and hold times around the
rising edge of CLK. Full bus-width WRITEs occur if all byte
write enables are LOW.
(a) 58, 59, 62, 63, (a) 52, 53, 56-59, DQa Input/ SRAM Data I/Os: Byte “a” is DQa pins; Byte “b” is DQb
68, 69, 72-74 62, 63 Output pins; Byte “c” is DQc pins; Byte “d” is DQd pins. Input data
(b) 8, 9, 12, 13, (b) 68, 69, 72-75, DQb must meet setup and hold times around the rising edge
18, 19, 22-24 78, 79 CLK.
(c) 2, 3, 6-9, DQc
12, 13
(d) 18, 19, 22-25, DQd
28, 29
N/A 51 NC/DQa NC/ No Connect/Data Bits: On the x32 version, these pins are
80 NC/DQb I/O no connect (NC) and can be left floating or connected to
1NC/DQc GND to minimize thermal impedance. On the x36 version,
30 NC/DQd these bits are DQs.
31 31 MODE Input Mode: This input selects the burst sequence. A LOW on
(LBO#) this pin selects linear burst. NC or HIGH on this pin selects
interleaved burst. Do not alter input state while device is
operating. LBO# is the JEDEC-standard term for MODE.
1-3, 6, 7, 25, N/A NC NC No Connect: These pins can be left floating or connected
28-30, 51-53, 56, to GND to minimize thermal impedance.
57, 75, 78, 79,
95, 96
83, 84 83, 84 NF –No Function: These pins are internally connected to the
die and will have the capacitance of input pins. It is
allowable to leave these pins unconnected or driven by
signals. Reserved for address expansion, pin 83 becomes
an SA at 8Mb density and pin 84 becomes an SA at 16Mb
density.
38, 39, 42, 43 38, 39, 42, 43 DNU –Do Not Use: These signals may either be unconnected or
wired to GND to minimize thermal impedance.
15, 16, 41, 65, 91 15, 16, 41, 65, 91 V
DD
Supply Power Supply:
See DC Electrical Characteristics and
Operating Conditions for range.
4, 11, 20, 27, 4, 11, 20, 27, V
DD
Q Supply Isolated Output Buffer Supply:
See DC Electrical
54, 61, 70, 77 54, 61, 70, 77 Characteristics and Operating Conditions for range.
5, 10, 14, 17, 21, 5, 10, 14, 17, 21, V
SS
Supply Ground:
GND.
26, 40, 55, 60, 26, 40, 55, 60,
66, 67, 71, 76, 90 66, 67, 71, 76, 90