急，谁能提供给我74ls245的功能说明和引脚图，谢谢了
发布网友
发布时间：2022-04-22 05:28
共2个回答
热心网友
时间：2023-08-24 22:07
74ls245引脚图与用法
74LS245引脚图
74LS245是我们常用的芯片，用来驱动led或者其他的设备,用法很简单如上图,这里简单的给出一些资料，他是8路同相三态双向总线收发器，可双向传输数据。
74LS245还具有双向三态功能，既可以输出，也可以输入数据。
当8051单片机的P0口总线负载达到或超过P0最大负载能力时，必须接入74LS245等总线驱动器。
当片选端/CE低电平有效时，DIR=“0”，信号由 B 向 A 传输；（接收）
*DIR=“1”，信号由 A 向 B 传输；（发送）当/CE为高电平时，A、B均为高阻态。
74LS245是我们常用的芯片，用来驱动led或者其他的设备，它是8路同相三态双向总线收发器，可双向传输数据。
*74LS245还具有双向三态功能，既可以输出，也可以输入数据。
*当8051单片机的P0口总线负载达到或超过P0最大负载能力时，必须接入74LS245等总线驱动器。
*当片选端/CE低电平有效时，DIR=“0”，信号由 B 向 A 传输；（接收）
*DIR=“1”，信号由 A 向 B 传输；（发送）当/CE为高电平时，A、B均为高阻态。
由于P2口始终输出地址的高8位，接口时74LS245的三态控制端/1G和/2G接地，P2口与驱动器输入线对应相连。
P0口与74LS245输入端相连,/E端接地，保证数据现畅通。8051的/RD和/PSEN相与后接DIR，使得/RD或/PSEN有效时，74LS245输入（P0.i←Di），其它时间处于输出（P0.i→Di）。
不好意思，图片太大弄不上
热心网友
时间：2023-08-24 22:08
我的资料是PDF的，图贴不上去，文字部分如下
TL/F/13
54LS245/DM54LS245/DM74LS245 TRI-STATE Octal Bus Transceiver
June 19
54LS245/DM54LS245/DM74LS245
TRI-STATEÉ Octal Bus Transceiver
General Description
These octal bus transceivers are 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 upon the logic
level at the direction control (DIR) input. The enable input
(G) can be used to disable the device so that the buses are
effectively isolated.
Features
Y Bi-Directional bus transceiver in a high-density 20-pin
package
Y TRI-STATE outputs drive bus lines directly
Y PNP inputs rece DC loading on bus lines
Y Hysteresis at bus inputs improve noise margins
Y Typical propagation delay times, port-to-port 8 ns
Y Typical enable/disable times 17 ns
Y IOL (sink current)
54LS 12 mA
74LS 24 mA
Y IOH (source current)
54LS b12 mA
74LS b15 mA
Y Alternate Military/Aerospace device (54LS245) is available.
Contact a National Semiconctor Sales Office/
Distributor for specifications.
Connection Diagram
Dual-In-Line Package
TL/F/13±1
Order Number 54LS245DMQB, 54LS245FMQB, 54LS245LMQB,
DM54LS245J, DM54LS245W, DM74LS245WM or DM74LS245N
See NS Package Number E20A, J20A, M20B, N20A or W20A
Function Table
Enable
Direction
Operation
G
Control
DIR
L L B data to A bus
L H A data to B bus
H X Isolation
H e High Level, L e Low Level, X e Irrelevant
TRI-STATEÉ is a registered trademark of National Semiconctor Corporation.
C1995 National Semiconctor Corporation RRD-B30M105/Printed in U. S. A.
Absolute Maximum Ratings (Note)
If Military/Aerospace specified devices are required,
please contact the National Semiconctor Sales
Office/Distributors for availability and specifications.
Supply Voltage 7V
Input Voltage
DIR or G 7V
A or B 5.5V
Operating Free Air Temperature Range
DM54LS and 54LS b55§C to a125§C
DM74LS 0§C to a70§C
Storage Temperature Range b65§C to a150§C
Note: The ``Absolute Maximum Ratings'' are those values
beyond which the safety of the device cannot be guaranteed.
The device should not be operated at these limits. The
parametric values defined in the ``Electrical Characteristics''
table are not guaranteed at the absolute maximum ratings.
The ``Recommended Operating Conditions'' table will define
the conditions for actual device operation.
Recommended Operating Conditions
Symbol Parameter
DM54LS245 DM74LS245
Units
Min Nom Max Min Nom Max
VCC Supply Voltage 4.5 5 5.5 4.75 5 5.25 V
VIH High Level Input Voltage 2 2 V
VIL Low Level Input Voltage 0.7 0.8 V
IOH High Level Output Current b12 b15 mA
IOL Low Level Output Current 12 24 mA
TA Free Air Operating Temperature b55 125 0 70 §C
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min
Typ
Max Units
(Note 1)
VI Input Clamp Voltage VCC e Min, IIe b18 mA b1.5 V
HYS Hysteresis (VTa b VTb) VCC e Min 0.2 0.4 V
VOH High Level Output Voltage VCC e Min, VIH e Min DM74
2.7
VIL e Max, IOHe b1 mA
VCC e Min, VIL e Min DM54/DM74
2.4 3.4 V
VIL e Max, IOHe b3 mA
VCC e Min, VIH e Min DM54/DM74
2
VIL e 0.5V, IOH e Max
VOL Low Level Output Voltage VCC e Min IOL e 12 mA DM74 0.4
VIL e Max
IOL e Max DM54 0.4 V
VIH e Min
DM74 0.5
IOZH Off-State Output Current, VCC e Max VO e 2.7V
20 mA
High Level Voltage Applied VIL e Max
IOZL Off-State Output Current,
VIH e Min
VO e 0.4V
b200 mA
Low Level Voltage Applied
II Input Current at Maximum VCC e Max A or B VI e 5.5V 0.1
mA
Input Voltage
DIR or G VI e 7V 0.1
IIH High Level Input Current VCC e Max, VI e 2.7V 20 mA
IIL Low Level Input Current VCC e Max, VI e 0.4V b0.2 mA
IOS Short Circuit Output Current VCC e Max (Note 2) b40 b225 mA
ICC Supply Current Outputs High VCC e Max 48 70
Outputs Low 62 90 mA
Outputs at Hi-Z 95
Note 1: All typicals are at VCC e 5V, TA e 25§C.
Note 2: Not more than one output should be shorted at a time, not to exceed one second ration
2
Switching Characteristics VCC e 5V, TA e 25§C (See Section 1 for Test Waveforms and Output Load)
DM54/74
Symbol Parameter Conditions LS245 Units
Min Max
tPLH Propagation Delay Time, Low-to-High-Level Output 12 ns
tPHL Propagation Delay Time, High-to-Low-Level Output CL e 45 pF 12 ns
tPZL Output Enable Time to Low Level
RL e 667X 40 ns
tPZH Output Enable Time to High Level 40 ns
tPLZ Output Disable Time from Low Level CL e 5 pF 25 ns
tPHZ Output Disable Time from High Level
RL e 667X 25 ns
tPLH Propagation Delay Time, Low-to-High-Level Output 16 ns
tPHL Propagation Delay Time, High-to-Low-Level Output CL e 150 pF 17 ns
tPZL Output Enable Time to Low Level
RL e 667X 45 ns
tPZH Output Enable Time to High Level 45 ns
3
Physical Dimensions inches (millimeters)
Ceramic Leadless Chip Carrier Package (E)
Order Number 54LS245LMQB
NS Package Number E20A
20-Lead Ceramic Dual-In-Line Package (J)
Order Number 54LS245DMQB or DM54LS245J
NS Package Number J20A
4
Physical Dimensions inches (millimeters) (Continued)
20-Lead Small Outline Molded Package (M)
Order Number DM74LS245WM
NS Package Number M20B
20-Lead Molded Dual-In-Line Package (N)
Order Number DM74LS245N
NS Package Number N20A
5
54LS245/DM54LS245/DM74LS245 TRI-STATE Octal Bus Transceiver
Physical Dimensions inches (millimeters) (Continued)
20-Lead Ceramic Flat Package (W)
Order Number 54LS245FMQB or DM54LS245W
NS Package Number W20A
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