TI SN54ABT7820

SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
D
D
D
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Member of the Texas Instruments
Widebus  Family
Advanced BiCMOS Technology
Released as DSCC SMD (Standard
Microcircuit Drawing) 5962-9650901QXA
Independent Asynchronous Inputs and
Outputs
Two Separate 512 × 18 FIFOs Buffering
Data in Opposite Directions
Programmable Almost-Full/Almost-Empty
Flag
Empty, Full, and Half-Full Flags
Fast Access Times of 12 ns With a 50-pF
Load and Simultaneous Switching Data
Outputs
Packaged in 84-Pin Ceramic Pin Grid
Array
D
D
D
GB PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
9
10 11
A
B
C
D
E
F
G
H
J
K
L
description
A FIFO memory is a storage device that allows data to be written into and read from its array at independent
data rates. The SN54ABT7820 is arranged as two 512 × 18-bit FIFOs for high speed and fast access times.
It processes data at rates up to 40 MHz, with access times of 18 ns in a bit-parallel format.
The SN54ABT7820 consists of bus transceiver circuits, two 512 × 18 FIFOs, and control circuitry arranged for
multiplexed transmission of data directly from the data bus or from the internal FIFO memories. Enable inputs
GAB and GBA control the transceiver functions. The SAB and SBA control inputs select whether real-time or
stored data is transferred. The circuitry used for select control eliminates the typical decoding glitch that occurs
in a multiplexer during the transition between stored and real-time data. Figure 1 illustrates the eight
fundamental bus-management functions that can be performed with the SN54ABT7820.
The SN54ABT7820 is characterized for operation over the full military temperature range of –55°C to 125°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Widebus is a trademark of Texas Instruments.
Copyright  1998, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
On products compliant to MIL-PRF-38535, all parameters are tested
unless otherwise noted. On all other products, production
processing does not necessarily include testing of all parameters.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
Terminal Assignments
TERMINAL
NAME
TERMINAL
NAME
TERMINAL
NAME
TERMINAL
A1
PENA
B11
FULLB
F9
NC
K2
A11
A2
GBA
C1
GND
F10
B6
K3
GND
A3
SBA
C2
HFA
F11
GND
K4
A4
LDCKA
C5
UNCKB
G1
A5
K5
VCC
GND
A5
VCC
VCC
C6
NC
G2
GND
K6
A17
C7
G3
A4
K7
GND
C10
G9
B4
K8
A8
VCC
LDCKB
VCC
HFB
C11
GND
G10
GND
K9
VCC
GND
A9
SAB
D1
A1
G11
B5
K10
B10
A10
GAB
D2
A0
H1
A7
K11
B9
A11
AF/AEB
D10
B0
H2
GND
L1
A10
B1
FULLA
D11
B1
H10
GND
L2
A12
B2
AF/AEA
E1
A3
H11
B7
L3
A13
B3
RSTA
E2
A2
J1
A8
L4
A14
B4
GND
E3
J2
A16
EMPTYB
E9
J5
VCC
A15
L5
B5
VCC
VCC
L6
B15
B6
UNCKA
E10
B2
J6
NC
L7
B16
B7
EMPTYA
E11
B3
J7
B17
L8
B14
B8
GND
F1
A6
J10
L9
B13
B9
RSTB
F2
GND
J11
VCC
B8
L10
B12
B10
PENB
F3
NC
K1
A9
L11
B11
A6
A7
2
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
NAME
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
Terminal Functions
TERMINAL
NAME
I/O
DESCRIPTION
A0 – A17
I/O
Port-A data. The 18-bit bidirectional data port for side A.
AF/AEA
O
FIFO A almost-full/almost-empty flag. Depth offset values can be programmed for AF/AEA, or the default value of 128
can be used for both the almost-empty offset (X) and the almost-full offset (Y). AF/AEA is high when FIFO A contains
X or fewer words or (512 – Y) or more words. AF/AEA is set high after FIFO A is reset.
AF/AEB
O
FIFO B almost-full/almost-empty flag. Depth offset values can be programmed for AF/AEB, or the default value of 128
can be used for both the almost-empty offset (X) and the almost-full offset (Y). AF/AEB is high when FIFO B contains
X or fewer words or (512 – Y) or more words. AF/AEB is set high after FIFO B is reset.
B0 – B17
I/O
Port-B data. The 18-bit bidirectional data port for side B.
EMPTYA
O
FIFO A empty flag. EMPTYA is low when FIFO A is empty and is high when FIFO A is not empty. EMPTYA is set low
after FIFO A is reset.
EMPTYB
O
FIFO B empty flag. EMPTYB is low when FIFO B is empty and is high when FIFO B is not empty. EMPTYB is set low
after FIFO B is reset.
FULLA
O
FIFO A full flag. FULLA is low when FIFO A is full and is high when FIFO A is not full. FULLA is set high after FIFO A
is reset.
FULLB
O
FIFO B full flag. FULLB is low when FIFO B is full and is high when FIFO B is not full. FULLB is set high after FIFO B
is reset.
GAB
I
Port-B output enable. B0 – B17 outputs are active when GAB is high and are in the high-impedance state when GAB
is low.
GBA
I
Port-A output enable. A0 – A17 outputs are active when GBA is high and are in the high-impedance state when GBA
is low.
HFA
O
FIFO A half-full flag. HFA is high when FIFO A contains 256 or more words and is low when FIFO A contains 255 or
fewer words. HFA is set low after FIFO A is reset.
HFB
O
FIFO B half-full flag. HFB is high when FIFO B contains 256 or more words and is low when FIFO B contains 255 or
fewer words. HFB is set low after FIFO B is reset.
LDCKA
I
FIFO A load clock. Data is written into FIFO A on a low-to-high transition of LDCKA when FULLA is high. The first word
written into an empty FIFO A is sent directly to the FIFO A data outputs.
LDCKB
I
FIFO B load clock. Data is written into FIFO B on a low-to-high transition of LDCKB when FULLB is high. The first word
written into an empty FIFO B is sent directly to the FIFO B data outputs.
PENA
I
FIFO A program enable. After reset and before a word is written into FIFO A, the binary value on A0 – A7 is latched as
an AF/AEA offset value when PENA is low and LDCKA is high.
PENB
I
FIFO B program enable. After reset and before a word is written into FIFO B, the binary value on B0 – B7 is latched as
an AF/AEB offset value when PENB is low and LDCKB is high.
RSTA
I
FIFO A reset. A low level on RSTA resets FIFO A, forcing EMPTYA low, HFA low, FULLA high, and AF/AEA high.
RSTB
I
FIFO B reset. A low level on RSTB resets FIFO B, forcing EMPTYB low, HFB low, FULLB high, and AF/AEB high.
SAB
I
Port-B read select. SAB selects the source of B0 – B17 read data. A low level selects real-time data from A0 – A17. A
high level selects the FIFO A output.
SBA
I
Port-A read select. SBA selects the source of A0 – A17 read data. A low level selects real-time data from B0 – B17. A
high level selects the FIFO B output.
UNCKA
I
FIFO A unload clock. Data is read from FIFO A on a low-to-high transition of UNCKA when EMPTYA is high.
UNCKB
I
FIFO B unload clock. Data is read from FIFO B on a low-to-high transition of UNCKB when EMPTYB is high.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
3
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
logic symbol†
SAB
SBA
GAB
GBA
RSTA
PENA
LDCKA
UNCKA
FULLA
EMPTYA
A9
A3
A10
A2
A1
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
EN1
EN2
RESET B
PROG ENA
PROG ENB
LDCKA
LDCKB
A4
B6
B1
B7
AF/AEA
A0
MODE
0
B3
B2
HFA
1
Φ
FIFO
512 × 18 × 2
SN54ABT7820
C2
D2
UNCKA
UNCKB
EMPTYB
ALMOST-FULL/
ALMOST-EMPTY B
HALF-FULL B
0
0
D1
B11
B5
A11
C10
D10
D11
E2
E10
E1
E11
G3
G9
G1
G11
F1
F10
H1
H11
J1
J11
K1
A Data
K11
B Data
L1
K10
K2
L11
L2
L10
L3
L9
L4
L8
J5
L6
L5
L7
K6
RSTB
PENB
LDCKB
UNCKB
FULLB
EMPTYB
AF/AEB
HFB
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B12
B13
B14
J7
17
17
† This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
4
A8
FULLB
HALF-FULL A
B10
C5
FULLA
EMPTYA
ALMOST-FULL/
ALMOST-EMPTY A
B9
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
B15
B16
B17
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
logic diagram (positive logic)
SAB
SBA
Φ
FIFO B
512 × 18
HFB
RSTB
AF/AEB
PENB
EMPTYB
FULLB
UNCKB
LDCKB
Q
GBA
[1]
D
B0
[2]
[3]
[4]
1 of 18 Channels
[15]
[16]
To Other Channels
[17]
[18]
GAB
Φ
FIFO A
512 × 18
RSTA
PENA
HFA
AF/AEA
EMPTYA
UNCKA
FULLA
LDCKA
A0
D
[1]
Q
[2]
[3]
[4]
1 of 18 Channels
[15]
[16]
To Other Channels
[17]
[18]
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
5
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
In
FIFO A
Out
Bus A
Bus B
Bus A
Bus B
FIFO B
Out
In
FIFO B
Out
In
SAB SBA GAB GBA
L
X
H
L
In
SAB SBA GAB GBA
X
X
L
L
FIFO A
Out
In
Bus A
Bus B
Bus B
FIFO B
Out
In
SAB SBA GAB GBA
X
L
L
H
SAB SBA GAB GBA
H
L
H
H
FIFO A
Out
In
Bus A
Bus B
Bus B
FIFO B
Out
In
SAB SBA GAB GBA
H
X
H
L
SAB SBA GAB GBA
L
H
H
H
FIFO A
Out
In
FIFO A
Out
Bus A
Bus A
Bus B
Bus B
FIFO B
Out
In
FIFO B
Out
In
SAB SBA GAB GBA
X
H
L
H
SAB SBA GAB GBA
H
H
H
H
Figure 1. Bus-Management Functions
6
FIFO A
Out
Bus A
FIFO B
Out
In
In
FIFO A
Out
Bus A
FIFO B
Out
In
In
FIFO A
Out
In
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
SELECT-MODE CONTROL TABLE
OPERATION
CONTROL
SBA
SAB
A BUS
B BUS
L
L
Real-time B to A bus
Real-time A to B bus
H
L
FIFO B to A bus
Real-time A to B bus
L
H
Real-time B to A bus
FIFO A to B bus
H
H
FIFO B to A bus
FIFO A to B bus
OUTPUT-ENABLE CONTROL TABLE
OPERATION
CONTROL
GBA
GAB
A BUS
B BUS
L
L
Isolation/input to A bus
Isolation/input to B bus
H
L
A bus enabled
Isolation/input to B bus
L
H
Isolation/input to A bus
B bus enabled
H
H
A bus enabled
B bus enabled
Figure 1. Bus-Management Functions (Continued)
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
7
0
Î
Î
Î
É
Î
É
Î
Î
Î
Î
ÎÎ
Î
Î
Î
Î
Î
Î
ÎÎ
ÎÎ
Î
Î
ÎÎ
ÎÎ
Î
Î
ÎÎ
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
Î
ÎÎ
Î
Î
Î
Î
Î
Î
Î
Î
Î
ÎÎ
LDCKA
A0 – A17
Word
1
Word
129
Word
2
Word
256
Word
384
Word
512
Don’t Care
Word
2
Word 1
Q0 – Q17
Word
129
Word
130
Word
257
Word
258
Word
384
Word
385
Î
Î
Î
Î
ÎÎ
POST OFFICE BOX 655303
Î
Î
ÎÎ
Î
ÎÎ
Î
UNCKA
Word
512
Invalid
• DALLAS, TEXAS 75265
EMPTYA
FULLA
HFA
AF/AEA
Set X = Y = 128
Empty + X
Half-Full
Full – Y
Full
Full – Y
† SAB = GAB = H, GBA = L
Operation of FIFO B is identical to that of FIFO A.
†
Figure 2. Timing Diagram for FIFO A
Half-Full
Empty + X
Empty
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
1
PENA
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
8
RSTA
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
offset values for almost-full/almost-empty (AF/AE) flagFigure 2
The AF/AE flag of each FIFO has two programmable limits: the almost-empty offset value (X) and the almost-full
offset value (Y). The offsets of a flag can be programmed from the input of its FIFO after it is reset and before
any data is written to its memory. An AF/AE flag is high when its FIFO contains X or fewer words or (512 – Y)
or more words.
To program the offset values for AF/AEA, PENA can be brought low after FIFO A is reset and only when LDCKA
is low. On the following low-to-high transition of LDCKA, the binary value on A0 – A7 is stored as the
almost-empty offset value (X) and the almost-full offset value (Y). Holding PENA low for another low-to-high
transition of LDCKA reprograms Y to the binary value on A0 – A7 at the time of the second LDCKA low-to-high
transition.
PENA can be brought back high only when LDCKA is low during the first two LDCKA cycles. PENA can be
brought high at any time after the second LDCKA pulse returns low. A maximum value of 255 can be
programmed for either X or Y (see Figure 3). To use the default values of X = Y = 128 for AF/AEA, PENA must
be tied high. No data is stored in the FIFO when its AF/AE offsets are programmed.
The AF/AEB flag is programmed in the same manner. PENB enables LDCKB to program the AF/AEB offset
values taken from B0 – B7.
RSTA
LDCKA
1
ÌÌÌÌÌÌÌÌÌÌÌ
ÌÌÌÌÌÌÌÌÌÌÌ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÌÌÌÌÌ
ÌÌÌÌÌ
ÌÌÌÌÌ
2
ÏÏÏÏÏÏÏÏ
ÏÏÏÏÏÏÏÏ
PENA
A0 – A17
X and Y
Y
Word 1
EMPTYA
Figure 3. Programming X and Y Separately for AF/AEA
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
9
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
absolute maximum ratings over operating free-air temperature (unless otherwise noted)†
Supply voltage range, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.5 V to 7 V
Input voltage range, VI (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.5 V to VCC + 0.5 V
Voltage range applied to any output in the high state or power-off state, VO . . . . . . . . . . . . . . – 0.5 V to 5.5 V
Current into any output in the low state, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 mA
Input clamp current, IIK (VI < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 18 mA
Output clamp current, IOK (VO < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 50 mA
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: The input and output negative-voltage ratings may be exceeded if the input and output clamp-current ratings are observed.
recommended operating conditions
VCC
VIH
Supply voltage
VIL
VI
Low-level input voltage
IOH
IOL
∆t / ∆v
Input transition rise or fall rate
TA
Operating free-air temperature
High-level input voltage
MIN
NOM
MAX
4.5
5
5.5
2
UNIT
V
V
0.8
V
V
High-level output current
VCC
–12
Low-level output current
24
mA
5
ns / V
Input voltage
0
– 55
125
mA
°C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
VIK
TEST CONDITIONS
VCC = 4.5 V,
VCC = 4.5 V,
II = – 18 mA
IOH = – 3 mA
VCC = 5 V,
VCC = 4.5 V,
IOH = – 3 mA
IOH = – 12 mA
VOL
II
VCC = 4.5 V,
VCC = 5.5 V,
IOL = 24 mA
VI = VCC or GND
IOZH§
IOZL §
VCC = 5.5 V,
VCC = 5.5 V,
VO = 2.7 V
VO = 0.5 V
IO ¶
VCC = 5.5 V,
VO = 2.5 V
VOH
ICC
VCC = 5.5 V,
Ci
Control inputs
Co
Flags
Cio
A or B ports
IO = 0,
MIN
MAX
UNIT
– 1.2
V
2.5
2
– 40
VI = VCC or GND
– 100
0.55
V
±5
µA
50
µA
– 50
µA
– 180
mA
Outputs high
15
Outputs low
95
Outputs disabled
15
VI = 2.5 V or 0.5 V
VO = 2.5 V or 0.5 V
POST OFFICE BOX 655303
V
3
VO = 2.5 V or 0.5 V
‡ All typical values are at VCC = 5 V, TA = 25°C.
§ The parameters IOZH and IOZL include the input leakage current.
¶ Not more than one output should be tested at a time, and the duration of the test should not exceed one second.
10
TYP‡
• DALLAS, TEXAS 75265
mA
6
pF
4
pF
8
pF
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
timing requirements over recommended operating free-air temperature range (unless otherwise
noted) (see Figure 4)
MIN
fclock
tw
Clock frequency
Pulse duration
LDCKA, LDCKB high
9
LDCKA, LDCKB low
9
UNCKA, UNCKB high
9
UNCKA, UNCKB low
th
Setup time
Hold time
UNIT
40
MHz
ns
9
RSTA, RSTB low
tsu
MAX
10
A0 – A17 before LDCKA↑ and B0 – B17 before LDCKB↑
4
PENA before LDCKA↑ and PENB before LDCKB↑
6
LDCKA inactive before RSTA high and LDCKB inactive before RSTB high
4
A0 – A17 after LDCKA↑ and B0 – B17 after LDCKB↑
0
PENA after LDCKA low and PENB after LDCKB low
3
LDCKA inactive after RSTA high and LDCKB inactive after RSTB high
4
ns
ns
switching characteristics over recommended ranges of supply voltage and operating free-air
temperature, CL = 50 pF (unless otherwise noted) (see Figure 4)
PARAMETER
FROM (INPUT)
fmax
LDCK, UNCK
tpd
d
tPLH
TO (OUTPUT)
LDCKA↑, LDCKB↑
B/A
EMPTYA, EMPTYB
UNCKA↑, UNCKB↑
tPHL
RSTA low, RSTB low
LDCKA↑, LDCKB↑
EMPTYA EMPTYB
EMPTYA,
FULLA, FULLB
UNCKA↑, UNCKB↑
tPLH
tpd
d
tPLH
tPHL
tpd
d
ten
tdis
RSTA low,
RSTB low
LDCKA↑, LDCKB↑
UNCKA↑, UNCKB↑
MAX
40
UNCKA↑, UNCKB↑
LDCKA↑, LDCKB↑
MIN
FULLA, FULLB
AF/AEA AF/AEB
AF/AEA,
UNIT
MHz
3
18
3
15
3
17
3
16
5
18
5
16
5
17
7
22
7
18
7
18
ns
ns
ns
ns
ns
RSTA low, RSTB low
AF/AEA, AF/AEB
1
16
LDCKA↑, LDCKB↑
HFA, HFB
6
17
7
17
1
16
1
12
1
11
1
10
ns
1
13
ns
UNCKA, UNCKB
RSTA low, RSTB low
SAB/SBA†
HFA HFB
HFA,
B/A
A/B
GBA/GAB
A/B
GBA/GAB
A/B
† These parameters are measured with the internal output state of the storage register opposite that of the bus input.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
ns
ns
ns
11
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
PARAMETER MEASUREMENT INFORMATION
7V
PARAMETER
S1
ten
500 Ω
From Output
Under Test
Test
Point
tdis
tpd
500 Ω
CL = 50 pF
(see Note A)
S1
tPZH
tPZL
tPHZ
tPLZ
tPLH
tPHL
LOAD CIRCUIT
Open
Closed
Open
Closed
Open
Open
tw
3V
3V
Timing
Input
1.5 V
0V
0V
VOLTAGE WAVEFORMS
PULSE DURATION
th
3V
Data
Input
1.5 V
3V
1.5 V
0V
VOLTAGE WAVEFORMS
SETUP AND HOLD TIMES
1.5 V
0V
1.5 V
VOL
Output
Waveform 2
S1 at Open
VOL + 0.3 V
1.5 V
VOH – 0.3 V
VOH
≈0V
NOTE A: CL includes probe and jig capacitance.
Figure 4. Load Circuit and Voltage Waveforms
• DALLAS, TEXAS 75265
VOL
tPHZ
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES
POST OFFICE BOX 655303
tPLZ
1.5 V
tPZH
VOH
12
1.5 V
≈ 3.5 V
Output
Waveform 1
S1 at 7 V
tPHL
1.5 V
1.5 V
0V
1.5 V
tPLH
Output
Control
tPZL
3V
Output
1.5 V
1.5 V
tsu
Input
Input
SN54ABT7820
512 × 18 × 2
STROBED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY
SGBS303E – AUGUST 1994 – REVISED APRIL 2000
TYPICAL CHARACTERISTICS
PROPAGATION DELAY TIME
vs
LOAD CAPACITANCE
SUPPLY CURRENT
vs
CLOCK FREQUENCY
160
VCC = 5 V
TA = 25°C
RL = 500 Ω
VCC = 5.5 V
140
I CC(f) – Supply Current – mA
t pd – Propagation Delay Time – ns
typ + 6
TA = 75°C
CL = 0 pF
typ + 4
typ + 2
typ
120
VCC = 5 V
100
80
VCC = 4.5 V
60
40
typ – 2
0
50
100
150
200
250
300
20
10 15 20 25 30 35 40 45
CL – Load Capacitance – pF
50 55 60 65 70
fclock – Clock Frequency – MHz
Figure 6
Figure 5
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
13
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