Datasheet

UNISONIC TECHNOLOGIES CO., LTD
U74AHC245
CMOS IC
OCTAL BUS TRANSCEIVERS
WITH 3-STATE OUTPUTS

DESCRIPTION
The U74AHC245 octal bus transceivers is designed for
asynchronous two-way communication between data buses. The
control-function implementation minimizes external timing
requirements.
The device allows data transmission from the A bus to the B
bus or from the B bus to the A bus, depending on the logic level at
the direction-control (DIR) input. The output-enable ( OE ) input can
be used to disable the device so that the buses are effectively
isolated.
To ensure the high-impedance state during power up or power
down, OE should be tied to VCC through a pullup resistor; the
minimum value of the resistor is determined by the current-sinking
capability of the driver.

FEATURES
* Operating range 2V to 5.5V VCC

ORDERING INFORMATION
Ordering Number
U74AHC245G-P20-R
U74AHC245G-R20-R
U74AHC245G-S20-R

Package
TSSOP-20
SSOP-20
SOP-20
Packing
Tape Reel
Tape Reel
Tape Reel
MARKING
www.unisonic.com.tw
Copyright © 2014 Unisonic Technologies Co., Ltd
1 of 5
QW-R502-987.B
U74AHC245
CMOS IC

PIN CONFIGURATION

FUNCTION TABLE
INPUT
OE
H
L
L
Note: H: HIGH voltage level;
L: LOW voltage level;
X: Don’t care

FUNCTION
DIR
X
H
L
Isolation
Transmit data from A bus to B bus
Transmit data from B bus to A bus
LOGIC DIAGRAM
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
2 of 5
QW-R502-987.B
U74AHC245

CMOS IC
ABSOLUTE MAXIMUM RATING (TA=25°С, unless otherwise specified)
PARAMETER
SYMBOL
RATINGS
UNIT
Supply Voltage
VCC
-0.5~7.0
V
Input Voltage Range
VI
-0.5~7.0
V
Output Voltage Range
VO
-0.5~VCC+0.5
V
Input Clamp Current (ViN<0)
IIK
-20
mA
Output Clamp Current (VO<0 or VO>VCC)
IOK
±20
mA
Output Current
IOUT
±25
mA
VCC or GND Current
ICC
±75
mA
Storage Temperature
TSTG
-65 ~ +150
°C
Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2. The input and output voltage ratings may be exceeded if the input and output current ratings are
observed.

RECOMMENDED OPERATING CONDITIONS (TA=25°С, unless otherwise specified)
PARAMETER
Supply Voltage
Input Voltage
Output Voltage
Operating Temperature
Input Transition Rise or Fall Rate
SYMBOL
VCC
VIN
VOUT
TOPR
VCC =3.3V±0.3V
VCC =5V±0.5V
Operating Free-air Temperature

MIN
2
0
0
-40
TYP
∆t/∆v
TA
-40
MAX
5.5
5.5
VCC
85
100
20
85
UNIT
V
V
V
°C
ns/V
°C
THERMAL CHARACTERISTICS
PARAMETER
Junction to Ambient
SYMBOL
SOP-20
SSOP-20
TSSOP-20
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
θJA
RATINGS
80
96
103
UNIT
°C/W
°C/W
°C/W
3 of 5
QW-R502-987.B
U74AHC245

CMOS IC
ELECTRICAL CHARACTERISTICS (TA=25°С, unless otherwise specified)
PARAMETER
SYMBOL
HIGH-level input voltage
VIH
LOW-lever output voltage
VIL
High-Level Output Voltage
Low-Level Output Voltage
VOH
VOL
TEST CONDITIONS
VCC=2V
VCC=3V
VCC=5.5V
VCC=2V
VCC=3V
VCC=5.5V
VCC=2V, IOH=-50μA
VCC=3V, IOH=-50μA
VCC=4.5V, IOH=-50μA
VCC=3V, IOH=-4mA
VCC=4.5V, IOH=-8mA
VCC=2V, IOL=50μA
VCC=3V, IOL=50μA
VCC=4.5V, IOL=50μA
VCC=3V, IOL=4mA
MIN
1.5
2.1
3.85
TYP
V
0.5
0.9
1.65
1.9
2.9
4.4
2.58
3.94
2
3
4.5
A or B inputs
OE or DIR
Output OFF-state current
Quiescent Supply Current
II(LEAK)
VCC=5.5V, VIN=VCC or GND
VCC=0 to 5.5V, VIN=VCC or GND
VCC=5.5V, VOUT=VCC or GND
VCC=5.5V, VIN=VCC or GND, IOUT=0
Input Capacitance( OE or DIR)
CI
VCC=5V, VIN=VCC or GND
2.5
Input Capacitance(A or B inputs)
CIO
VCC=5V, VIN=VCC or GND
4
±0.1
μA
±0.25
4
μA
μA
10
pF
pF
SWITCHING CHARACTERISTICS (RL=1kΩ, TA=25°С, unless otherwise specified)
PARAMETER
SYMBOL
Propagation delay from input
(A or B) to output (B or A)
tpd
(tPLH/tPHL)
3-state output enable time from input
ten
(tPZL/tPZH)
( OE ) to output (A or B)
3-state output disable time from
input ( OE ) to output (A or B)

V
0.36
IOZ
IQ

V
V
0.1
0.1
0.1
0.36
VCC=4.5V, IOL=8mA
Input Leakage Current
MAX UNIT
tdis
(tPLZ/tPHZ)
TEST CONDITIONS
VCC=3.3V±0.3V, CL=15pF
VCC=3.3V±0.3V, CL=50pF
VCC=5V±0.5V, CL=15pF
VCC=5V±0.5V, CL=50pF
VCC=3.3V±0.3V, CL=15pF
VCC=3.3V±0.3V, CL=50pF
VCC=5V±0.5V, CL=15pF
VCC=5V±0.5V, CL=50pF
VCC=3.3V±0.3V, CL=15pF
VCC=3.3V±0.3V, CL=50pF
VCC=5V±0.5V, CL=15pF
VCC=5V±0.5V, CL=50pF
MIN
TYP MAX UNIT
5.8
8.4
8.3 11.9
ns
4
5.5
5.5
7.5
8.5 13.2
11 16.7
ns
5.8
8.5
7.3 10.6
8.9 12.5
11.5 15.8
ns
5.6
7.8
7
9.7
OPERATING CHARACTERISTICS(VCC=5V, TA=25°С, unless otherwise specified)
PARAMETER
Power Dissipation Capacitance
SYMBOL
CPD
TEST CONDITIONS
No load, f=1MHz
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
TYP MAX UNIT
14
pF
4 of 5
QW-R502-987.B
U74AHC245

CMOS IC
TEST CIRCUIT AND WAVEFORMS
VCC
K1
From Output
CL
(Note 1)
RL
K2
Notes: 1. CL includes probe and jig capacitance.
2. All input pulses are supplied by generators having the following characteristics:
PRR≤1MHZ, ZO=50Ω, tr ≤ 3ns, tf ≤ 3ns.
3. The outputs are measured one at a time with one input transition per measurement.
Figure 1. Load Circuit and Voltage Waveforms
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
5 of 5
QW-R502-987.B