Datasheet 搜索 > 逻辑控制器 > TI（德州仪器） > TCA9546APWR 数据手册 > TCA9546APWR 数据手册 17/30 页
器件3D模型￥ 2.519
TCA9546APWR 数据手册 - TI（德州仪器）
制造商:
TI（德州仪器）
分类:
逻辑控制器
封装:
TSSOP-16
描述:
TCA9546APWR 编带
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
页面导航:
引脚图在P3Hot
典型应用电路图在P16P17P18
原理图在P10P16
封装尺寸在P23P25P26
标记信息在P23
封装信息在P22P23P24P25P26
技术参数、封装参数在P4
应用领域在P1P16
电气规格在P5P6P17
导航目录
TCA9546APWR数据手册
Page:
of 30 Go
若手册格式错乱，请下载阅览PDF原文件
r
p(max)
b
R
0.8473 C
t
=
´
DPUX OL(max)
p(min)
OL
V V
R
I
-
=
TCA9546A
www.ti.com
SCPS205A –APRIL 2014–REVISED FEBRUARY 2015
Typical Application (continued)
10.2.1 Design Requirements
The A0, A1, and A2 pins are hardware selectable to control the slave address of the TCA9546A. These pins may
be tied directly to GND or V
CC
in the application.
If multiple slave channels will be activated simultaneously in the application, then the total I
OL
from SCL/SDA to
GND on the master side will be the sum of the currents through all pull-up resistors, R
p
.
The pass-gate transistors of the TCA9546A are constructed such that the V
CC
voltage can be used to limit the
maximum voltage that is passed from one I
2
C bus to another.
Figure 16 shows the voltage characteristics of the pass-gate transistors (note that the graph was generated using
data specified in the Electrical Characteristics section of this data sheet). In order for the TCA9546A to act as a
voltage translator, the V
pass
voltage must be equal to or lower than the lowest bus voltage. For example, if the
main bus is running at 5 V and the downstream buses are 3.3 V and 2.7 V, V
pass
must be equal to or below 2.7 V
to effectively clamp the downstream bus voltages. As shown in Figure 16, V
pass(max)
is 2.7 V when the TCA9546A
supply voltage is 4 V or lower, so the TCA9546A supply voltage could be set to 3.3 V. Pull-up resistors then can
be used to bring the bus voltages to their appropriate levels (see Figure 15).
10.2.2 Detailed Design Procedure
Once all the slaves are assigned to the appropriate slave channels and bus voltages are identified, the pull-up
resistors, R
p
, for each of the buses need to be selected appropriately. The minimum pull-up resistance is a
function of V
DPUX
, V
OL,(max)
, and I
OL
:
(1)
The maximum pull-up resistance is a function of the maximum rise time, t
r
(300 ns for fast-mode operation, f
SCL
=
400 kHz) and bus capacitance, C
b
:
(2)
The maximum bus capacitance for an I
2
C bus must not exceed 400 pF for fast-mode operation. The bus
capacitance can be approximated by adding the capacitance of the TCA9546A, C
io(OFF)
, the capacitance of
wires/connections/traces, and the capacitance of each individual slave on a given channel. If multiple channels
will be activated simultaneously, each of the slaves on all channels will contribute to total bus capacitance.
Copyright © 2014–2015, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: TCA9546A
器件 Datasheet 文档搜索
AiEMA 数据库涵盖高达 72,405,303 个元件的数据手册，每天更新 5,000 多个 PDF 文件
