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参数资料
| 型号： | N74F657DB |
| 厂商： | NXP SEMICONDUCTORS |
| 元件分类： | 总线收发器 |
| 英文描述： | Octal transceiver with 8-bit parit generator/checker |
| 中文描述： | F/FAST SERIES, 8-BIT TRANSCEIVER, TRUE OUTPUT, PDSO24 |
| 封装： | PLASTIC, SSOP-24 |
| 文件页数： | 5/12页 |
| 文件大小： | 109K |
| 代理商： | N74F657DB |
Philips Semiconductors
Product specification
74F657
Octal transceiver with 8-bit parity generator/checker
2
90 July 30
853 1117 00081
FEATURES
Combines 74F245 and 74F280A functions in one package
High impedance base input for reduced loading (70A in
high and low states)
Ideal in applications where high output drive and light bus
loading are required (IIL is 70A vs FAST std of 600A)
3–state buffer outputs sink 64mA and source 15mA
Input diodes for termination effects
24–pin plastic slim DIP (300mil) package
Industrial temperature range available (–40°C to +85°C)
DESCRIPTION
The 74F657 is an octal transceiver featuring non–inverting
buffers with 3–state outputs and an 8–bit parity
generator/checker, and is intended for bus–oriented
applications. The buffers have a guaranteed current sinking
capability of 24mA at the A ports and 64mA at the B ports.
The transmit/receive (T/R) input determines the direction of
the data flow through the bidirectional transceivers.
Transmit (active high) enables data from A ports to B ports;
receive (active low) enables data from B ports to A ports.
The output enable (OE) input disables both the A and B ports by
placing them in a high impedance condition when the OE input is
high
.
The parity select (ODD/EVEN) input gives the user the option of
odd or even parity systems
.
The parity (PARITY) pin is an output from the generator/checker
when transmitting from the port A to B (T/R = high) and an input
when receiving from port B to A port ( T/R = low).
When transmitting (T/R = high) the parity select (ODD/EVEN) input
is set, then the A port data is polled to determined the number of
high bits. The parity (PARITY) output then goes to the logic state
determined by the parity select (ODD/EVEN) setting and by the
number of high bits on port A.
For example, if the parity select (ODD/EVEN) is set low (even
parity), and the number of high bits on port A is odd, then the parity
(PARITY) output will be high, transmitting even parity. If the number
of high bits on port A is even, then the parity (PARITY) output will
be low, keeping even parity.
When in receive mode (T/R = low) the B port is polled to determine
the number of high bits. If parity select (ODD/EVEN) is low (even
parity) and the number of highs on port B is:
(1) odd and the parity (PARITY) input is high, then ERROR will be
high, significantly no error.
(2) even and the parity (PARITY) input is high, then ERROR will be
asserted low, indicating an error.
TYPE
TYPICAL PROPAGA-
TION DELAY
TYPICAL SUPPLY
CURRENT( TOTAL)
74F657
8.0ns
100mA
ORDERING INFORMATION
ORDER CODE
COMMERCIAL RANGE
INDUSTRIAL RANGE
DESCRIPTION
VCC = 5V ±10%,
PKG DWG #
Tamb = 0°C to +70°C
Tamb = –40°C to +85°C
24–pin plastic slim
DIP (300mil)
N74F657N
I74F657N
SOT222-1
24–pin plastic SOL
N74F657D
I74F657D
SOT137-1
24–pin plastic SSOP
N74F657DB
I74F657DB
SOT340-1
INPUT AND OUTPUT LOADING AND FAN OUT TABLE
PINS
DESCRIPTION
74F (U.L.)
HIGH/LOW
LOAD VALUE
HIGH/LOW
A0 – A7
A ports 3–state inputs
3.5/0.117
70
A/70A
B0 – B7
B ports 3–state inputs
3.5/0.117
70
A/70A
PARITY
Parity input
3.5/0.117
70
A/70A
T/R
Transmit/receive input
2.0/0.066
40
A/40A
ODD/EVEN
Parity select input
1.0/0.033
20
A/20A
OE
Output enable input (active low)
2.0/0.066
40
A/40A
A0 – A7
A ports 3–state outputs
150/40
3.0mA/24mA
B0 – B7
B ports 3–state outputs
750/106.7
15mA/64mA
PARITY
Parity output
750/106.7
15mA/64mA
ERROR
Error output
750/106.7
15mA/64mA
Note to input and output loading and fan out table
1. One (1.0) FAST unit load is defined as: 20
A in the high state and 0.6mA in the low state.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| N74F657DB-T | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Single 8-bit Bus Transceiver |
| N74F657D-T | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Single 8-bit Bus Transceiver |
| N74F657N | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Octal transceiver with 8-bit parit generator/checker |
| N74F657N,602 | 功能描述:总线收发器 OCTAL BUFFER W/PARITY GEN/CHEK RoHS:否 制造商:Fairchild Semiconductor 逻辑类型:CMOS 逻辑系列:74VCX 每芯片的通道数量:16 输入电平:CMOS 输出电平:CMOS 输出类型:3-State 高电平输出电流:- 24 mA 低电平输出电流:24 mA 传播延迟时间:6.2 ns 电源电压-最大:2.7 V, 3.6 V 电源电压-最小:1.65 V, 2.3 V 最大工作温度:+ 85 C 封装 / 箱体:TSSOP-48 封装:Reel |
| N74F670D | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:4 x 4 register file 3-State |
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