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| 型號： | PCA9509 |
| 廠商： | NXP Semiconductors N.V. |
| 英文描述： | Level translating I2C-bus/SMBus repeater |
| 中文描述： | 級別翻譯I2C-bus/SMBus中繼器 |
| 文件頁數(shù)： | 4/16頁 |
| 文件大?。?/td> | 92K |
| 代理商： | PCA9509 |
PCA9509_1
Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet
Rev. 01 — 27 June 2006
4 of 16
Philips Semiconductors
PCA9509
Level translating I
2
C-bus/SMBus repeater
pull-down driver is enabled until port A rises above approximately 0.15 V (V
ILc
), then
port B, if not externally driven LOW, will continue to rise being pulled up by the external
pull-up resistor.
Remark:
Ground offset between the PCA9509 ground and the ground of devices on
port A of the PCA9509 must be avoided.
The reason for this cautionary remark is that a CMOS/NMOS open-drain capable of
sinking 3 mA of current at 0.4 V will have an output resistance of 133
or less (R = E / I).
Such a driver will share enough current with the port A output pull-down of the PCA9509
to be seen as a LOW as long as the ground offset is zero. If the ground offset is greater
than 0 V, then the driver resistance must be less. Since V
ILc
can be as low as 90 mV at
cold temperatures and the low end of the current distribution, the maximum ground offset
should not exceed 50 mV.
Bus repeaters that use an output offset are not interoperable with the port A of the
PCA9509 as their output LOW levels will not be recognized by the PCA9509 as a LOW. If
the PCA9509 is placed in an application where the V
IL
of port A of the PCA9509 does not
go below its V
ILc
it will pull port B LOW initially when port A input transitions LOW but the
port B will return HIGH, so it will not reproduce the port A input on port B. Such
applications should be avoided.
Port B is interoperable with all I
2
C-bus slaves, masters and repeaters.
6.1 Enable
The EN pin is active HIGH and allows the user to select when the repeater is active. This
can be used to isolate a badly behaved slave on power-up until after the system power-up
reset. It should never change state during an I
2
C-bus operation because disabling during
a bus operation will hang the bus and enabling part way through a bus cycle could
confuse the I
2
C-bus parts being enabled.
The enable pin should only change state when the bus and the repeater port are in an idle
state to prevent system failures.
6.2 I
2
C-bus systems
As with the standard I
2
C-bus system, pull-up resistors are required to provide the logic
HIGH levels on the buffered bus (standard open-collector configuration of the I
2
C-bus).
The size of these pull-up resistors depends on the system. Each of the port A I/Os has an
internal pull-up current source and does not require the external pull-up resistor. Port B is
designed to work with Standard-mode and Fast-mode I
2
C-bus devices in addition to
SMBus devices. Standard-mode I
2
C-bus devices only specify 3 mA output drive; this
limits the termination current to 3 mA in a generic I
2
C-bus system where Standard-mode
devices and multiple masters are possible. Under certain conditions higher termination
currents can be used.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PCA9509A | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Smart, simple solutions for the 12 most common design concerns |
| PCA9509ADP,118 | 功能描述:接口-信號緩沖器、中繼器 I2CbusSMBus repeater RoHS:否 制造商:Texas Instruments 工作電源電壓: 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VSSOP-8 封裝:Reel |
| PCA9509ADP118 | 制造商:Rochester Electronics LLC 功能描述: 制造商:NXP 功能描述: 制造商:NXP Semiconductors 功能描述: |
| PCA9509AGM,125 | 功能描述:接口-信號緩沖器、中繼器 I2CbusSMBus repeater RoHS:否 制造商:Texas Instruments 工作電源電壓: 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VSSOP-8 封裝:Reel |
| PCA9509D | 功能描述:接口-信號緩沖器、中繼器 I2C LV LVL TRANSLATR RoHS:否 制造商:Texas Instruments 工作電源電壓: 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VSSOP-8 封裝:Reel |
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