Page 1
Low voltage CMOS octal bus buffer (3-state)
Features
■ 5V tolerant inputs and outputs
■ High speed:
–t
= 8.0ns (Max) at V
PD
■ Power down protection on inputs and outputs
■ Symmetrical output impedance:
–|I
■ PCI bus levels guaranteed at 24mA
■ Balanced propagation delays:
–t
■
Operating voltage range:
–V
■ Pin and function compatible with
| = IOL = 24mA (Min) at VCC = 3V
OH
≅ t
PLH
PHL
(Opr) = 2.0V to 3.6V
CC
74 series 541
■ Latch-up performance exceeds
500mA (JESD 17)
■ ESD performance:
– HBM > 2000V
(MIL STD 883 method 3015); MM > 200V
CC
= 3V
74LCX541
with 5V tolerant inputs and outputs
SO-20 TSSOP20
Description
The 74LCX541 is a low voltage CMOS octal bus
buffer (non-inverted) fabricated with sub-micron
silicon gate and double-layer metal wiring C
technology. It is ideal for low power and high
speed 3.3V applications; it can be interfaced to
5V signal environment for both inputs and
outputs.
The 3 STATE control gate operates as two input
AND such that if either G1 and G2 are high, all
eight outputs are in the high impedance state. In
order to enhance PC board layout the 74LCX541
offers a pinout having inputs and outputs on
opposite sides of the package.
2
MOS
It has same speed performance at 3.3V than 5V
AC/ACT family, combined with a lower power
consumption.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
Order codes
Part number Package Packaging
74LCX541MTR SO-20 Tape and reel
74LCX541TTR TSSOP20 Tape and reel
January 2007 Rev 5 1/17
www.st.com
17
Page 2
Contents 74LCX541
Contents
1 Logic symbols and I/O equivalent circuit . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Logic states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Truth table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Test circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7 Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2/17
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74LCX541 Logic symbols and I/O equivalent circuit
1 Logic symbols and I/O equivalent circuit
Figure 1. IEC logic symbols
Figure 2. Input and output equivalent circuit
3/17
Page 4
Pin settings 74LCX541
2 Pin settings
2.1 Pin connection
Figure 3. Pin connection (top through view)
2.2 Pin description
Table 1. Pin description
Pin N° Symbol Name and function
1, 19 G1
2, 3, 4, 5,
6, 7, 8, 9
18, 17, 16, 15,
14, 13, 12, 11
10 GND Ground (0V)
20 V
, G2 Output enable inputs
A1 to A8 Data inputs
Y1 to Y8 Data outputs
CC
Positive supply voltage
4/17
Page 5
74LCX541 Logic states
3 Logic states
3.1 Truth table
Table 2. Truth table
Input Output
G1
HXX Z
XHX Z
LLH L
LLL H
Note: X : Do not care
Z : High impedance
G2 An Yn
5/17
Page 6
Maximum rating 74LCX541
4 Maximum rating
Stressing the device above the rating listed in the “absolute maximum ratings” table may
cause permanent damage to the device. these are stress ratings only and operation of the
device at these or any other conditions above those indicated in the operating sections of
this specification is not implied. exposure to absolute maximum rating conditions for
extended periods may affect device reliability. refer also to the STMicroelectronics sure
program and other relevant quality documents.
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
V
V
V
I
I
I
GND
T
T
1. IO absolute maximum rating must be observed
2. VO < GND
Supply voltage -0.5 to +7.0 V
CC
V
DC input voltage -0.5 to +7.0 V
I
DC output voltage (OFF state) -0.5 to +7.0 V
O
DC output voltage (high or low state)
O
I
DC input diode current -50 mA
IK
DC output diode current
OK
I
DC output current ±50 mA
O
DC supply current per supply pin ± 100 mA
CC
(2)
(1)
-0.5 to VCC + 0.5
-50 mA
DC ground current per supply pin ± 100 mA
Storage temperature -65 to +150 °C
stg
Lead temperature (10 sec) 300 °C
L
V
4.1 Recommended operating conditions
Table 4. Recommended operating conditions
Symsbol Parameter Value Unit
V
V
V
V
Supply voltage
CC
Input voltage 0 to 5.5 V
I
Output voltage (OFF state) 0 to 5.5 V
O
Output voltage (high or low state)
O
IOH, IOLHigh or low level output current (VCC = 3.0 to 3.6V)
I
, IOLHigh or low level output current (VCC = 2.7V)
OH
T
dt/dv
1. Truth table guaranteed: 1.5V to 3.6V
2. VIN from 0.8V to 2V at VCC = 3.0V
Operating temperature -40 to 85 °C
op
Input rise and fall time
6/17
(1)
(2)
2.0 to 3.6 V
0 to V
CC
± 24 mA
± 12 mA
0 to 10 ns/V
V
Page 7
74LCX541 Electrical characteristics
5 Electrical characteristics
Table 5. DC specifications
Test condition Value
Symbol Parameter
V
CC
(V)
V
V
High level input voltage
IH
Low level input voltage 0.8 V
IL
2.7 to 3.6
2.7 to 3.6
2.7
V
High level output voltage
OH
3.0
2.7 to 3.6
2.7
V
Low level output voltage
OL
3.0
I
Input leakage current 2.7 to 3.6
I
I
I
I
∆I
Table 6. Dynamic switching characteristics
Power OFF leakage
off
current
High impedance output
OZ
leakage current
Quiescent supply current 2.7 to 3.6
CC
I incr. per Input 2.7 to 3.6
CC
0
2.7 to 3.6
IO = -100µAVCC-0.2
= -12mA
I
O
I
= -18mA
O
I
= -24mA
O
IO = 100µA
= 12mA
I
O
I
= 16mA
O
I
= 24mA
O
= 0 to 5.5V
V
I
VI or VO = 5.5V
V
= VIH or V
I
VO = 0 to V
V
= VCC or GND
I
V
or VO = 3.6 to 5.5V
I
= VCC - 0.6V
V
IH
IL
CC
-40 to 85°C
Min Max
2.0 V
2.2
2.4
2.2
0.2
0.4
0.4
0.55
± 5 µA
10 µA
± 5 µA
10
± 10
500 µA
Test condition Value
= 25 °C
Symbol Parameter
V
CC
(V)
V
OLP
V
OLV
1. Number of outputs defined as "n". Measured with "n-1" outputs switching from HIGH to LOW or LOW to
HIGH. The remaining output is measured in the LOW state.
Dynamic low level quiet
(1)
output
3.3
C
= 50pF
L
= 0V, VIH = 3.3V
V
IL
T
A
Min Typ Max
0.8
-0.8
Unit
V
V
µA
Unit
V
7/17
Page 8
Electrical characteristics 74LCX541
Table 7. AC electrical characteristics
Test condition Value
Symbol Parameter
t
PLH tPHL
Propagation delay
time
V
CC
(V)
C
(pF)
L
R
(Ω)
L
ts = t
(ns)
2.7 50 500 2.5 1.5 9.0 ns
3.0 to 3.6 1.5 8.0
r
-40 to 85 °C
Min Max
Unit
t
PZL tPZH
t
PLZ tPHZ
t
OSLH
t
OSHL
1. Skew is defined as the absolute value of the difference between the actual propagation delay for any two
outputs of the same device switching in the same direction, either HIGH or LOW (t
t
OSHL
2. Parameter guaranteed by design
Output enable
time
Output disable
time
output to output
skew time
= | t
PHLm
- t
PHLn
(1) (2)
|)
2.7 50 500 2.5 1.5 9.5 ns
3.0 to 3.6 1.5 8.5
2.7 50 500 2.5 1.5 8.5 ns
3.0 to 3.6 1.5 7.5
3.0 to 3.6 50 500 2.5 1.0 ns
OSLH
= | t
PLHm
- t
PLHn
Table 8. Capacitive characteristics
Test condition Value
T
Symbol Parameter
V
CC
(V)
= 0 to V
C
C
C
1. CPD is defined as the value of the IC’s internal equivalent capacitance which is calculated from the
operating current consumption without load. (Refer to Test Circuit). Average operating current can be
obtained by the following equation. I
Input capacitance 3.3
IN
Output capacitance 3.3
OUT
Power dissipation
PD
capacitance
(1)
3.3
= CPD x VCC x fIN + ICC/8 (per buffer)
CC(opr)
V
IN
= 0 to V
V
IN
fIN = 10MHz
= 0 or V
V
IN
CC
CC
CC
= 25 °C
A
Min Typ Max
6pF
12 pF
25 pF
|,
Unit
8/17
Page 9
74LCX541 Test circuit
6 Test circuit
Figure 4. Test circuit
Figure 5. Test circuit
Test Switch
t
t
t
PLH
PZL
PZH
, t
PHL
, t
PLZ
, t
PHZ
Open
6V
GND
CL = 50pF or equivalent (includes jig and probe capacitance)
R
= R1 = 500Ω or equivalent
L
R
= Z
T
of pulse generator (typically 50Ω)
OUT
9/17
Page 10
Waveforms 74LCX541
7 Waveforms
Figure 6. Propagation delays (f = 1MHz; 50% duty cycle)
Figure 7. Output enable and disable time (f = 1MHz; 50% duty cycle)
10/17
Page 11
74LCX541 Package mechanical data
8 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a Lead-free second level interconnect . The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
11/17
Page 12
Package mechanical data 74LCX541
SO-20 MECHANICAL DATA
DIM.
A 2.35 2.65 0.093 0.104
A1 0.1 0.30 0.004 0.012
B 0.33 0.51 0.013 0.020
C 0.23 0.32 0.009 0.013
D 12.60 13.00 0.496 0.512
E 7.4 7.6 0.291 0.299
e 1.27 0.050
H 10.00 10.65 0.394 0.419
h 0.25 0.75 0.010 0.030
L 0.4 1.27 0.016 0.050
k0° 8°0° 8°
ddd 0.100 0.004
MIN. TYP MAX. MIN. TYP. MAX.
mm. inch
12/17
0016022D
Page 13
74LCX541 Package mechanical data
TSSOP20 MECHANICAL DATA
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 1.2 0.047
A1 0.05 0.15 0.002 0.004 0.006
A2 0.8 1 1.05 0.031 0.039 0.041
b 0.19 0.30 0.007 0.012
c 0.09 0.20 0.004 0.0079
D 6.4 6.5 6.6 0.252 0.256 0.260
E 6.2 6.4 6.6 0.244 0.252 0.260
E1 4.3 4.4 4.48 0.169 0.173 0.176
e 0.65 BSC 0.0256 BSC
K0˚ 8˚0˚ 8˚
L 0.45 0.60 0.75 0.018 0.024 0.030
mm. inch
A2
A
A1
PIN 1 IDENTIFICATION
b
e
K
c
L
E
D
E1
1
0087225C
13/17
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Package mechanical data 74LCX541
Tape & Reel SO-20 MECHANICAL
mm. inch
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 60 2.362
T 30.4 1.197
Ao 10.8 11 0.425 0.433
Bo 13.2 13.4 0.520 0.528
Ko 3.1 3.3 0.122 0.130
Po 3.9 4.1 0.153 0.161
P 11.9 12.1 0.468 0.476
DATA
14/17
Page 15
74LCX541 Package mechanical data
Tape & Reel TSSOP20 MECHANICAL DATA
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 60 2.362
T 22.4 0.882
Ao 6.8 7 0.268 0.276
Bo 6.9 7.1 0.272 0.280
Ko 1.7 1.9 0.067 0.075
Po 3.9 4.1 0.153 0.161
P 11.9 12.1 0.468 0.476
mm. inch
15/17
Page 16
Revision history 74LCX541
9 Revision history
Table 9. Revision history
Date Revision Changes
15-Sep-2004 4 Ordering Codes Revision - pag. 1.
24-Jan-2007 5 The document has been reformatted, temperature ranges updated
16/17
Page 17
74LCX541
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