PA9517A 데이터 시트보기 (PDF) - NXP Semiconductors.
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PA9517A Datasheet PDF : 22 Pages
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NXP Semiconductors
PCA9517A
Level translating I2C-bus repeater
6.1 Enable
The EN pin is active HIGH with an internal pull-up to VCC(B) 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
I2C-bus operation because disabling during a bus operation will hang the bus and
enabling part way through a bus cycle could confuse the I2C-bus parts being enabled.
The enable pin should only change state when the global bus and the repeater port are in
an idle state to prevent system failures.
6.2 I2C-bus systems
As with the standard I2C-bus system, pull-up resistors are required to provide the logic
HIGH levels on the buffered bus (standard open-collector configuration of the I2C-bus).
The size of these pull-up resistors depends on the system, but each side of the repeater
must have a pull-up resistor. This part designed to work with Standard mode and Fast
mode I2C-bus devices in addition to SMBus devices. Standard mode I2C-bus devices only
specify 3 mA output drive; this limits the termination current to 3 mA in a generic I2C-bus
system where Standard-mode devices and multiple masters are possible. Under certain
conditions higher termination currents can be used.
Please see Application Note AN255, I2C/SMBus Repeaters, Hubs and Expanders for
additional information on sizing resistors and precautions when using more than one
PCA9517A in a system or using the PCA9517A in conjunction with other bus buffers.
7. Application design-in information
A typical application is shown in Figure 5. In this example, the system master is running
on a 3.3 V I2C-bus while the slave is connected to a 1.2 V bus. Both buses run at 400 kHz.
Master devices can be placed on either bus.
3.3 V
1.2 V
10 kΩ
SDA
SCL
BUS
MASTER
400 kHz
10 kΩ
VCC(B)
SDAB
SCLB
10 kΩ
VCC(A)
SDAA
SCLA
PCA9517A
EN
10 kΩ
SDA
SCL
SLAVE
400 kHz
bus B
bus A
002aad468
Fig 5. Typical application
The PCA9517A is 5 V tolerant, so it does not require any additional circuitry to translate
between 0.9 V to 5.5 V bus voltages and 2.7 V to 5.5 V bus voltages.
PCA9517A
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 4.1 — 24 May 2016
© NXP Semiconductors N.V. 2016. All rights reserved.
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