9517A 查看數據表（PDF） - NXP Semiconductors.

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9517A

Level translating I2C-bus repeater

NXP Semiconductors. 

NXP Semiconductors

PCA9517A

Level translating I2C-bus repeater

5.2 Pin description

Table 3.

Symbol

VCC(A)

SCLA

SDAA

GND

EN

SDAB

SCLB

VCC(B)

Pin description

Pin

SO8,

TSSOP8

1

2

3

4

5

6

7

8

HWSON8

7

8

1

2[1]

3

4

5

6

Description

port A supply voltage (0.9 V to 5.5 V)

serial clock port A bus

serial data port A bus

supply ground (0 V)

active HIGH repeater enable input

serial data port B bus

serial clock port B bus

port B supply voltage (2.7 V to 5.5 V)

[1] HWSON8 package die supply ground is connected to both GND pin and exposed center pad. GND pin

must be connected to supply ground for proper device operation. For enhanced thermal, electrical, and

board level performance, the exposed pad needs to be soldered to the board using a corresponding

thermal pad on the board and for proper head conduction through the board, thermal vias need to be

incorporated in the printed-circuit board in the thermal pad region.

6. Functional description

Refer to Figure 1 “Functional diagram of PCA9517A”.

The PCA9517A enables I2C-bus or SMBus translation down to VCC(A) as low as 0.9 V

without degradation of system performance. The PCA9517A contains two bidirectional

open-drain buffers specifically designed to support up-translation/down-translation

between the low voltage (as low as 0.9 V) and a 3.3 V or 5 V I2C-bus or SMBus. All inputs

and I/Os are overvoltage tolerant to 5.5 V even when the device is unpowered (VCC(B)

and/or VCC(A) = 0 V). The PCA9517A includes a power-up circuit that keeps the output

drivers turned off until VCC(B) is above 2.5 V and the VCC(A) is above 0.8 V. VCC(B) and

VCC(A) can be applied in any sequence at power-up. After power-up and with the enable

(EN) HIGH, a LOW level on port A (below 0.3VCC(A)) turns the corresponding port B driver

(either SDA or SCL) on and drives port B down to about 0.5 V. When port A rises above

0.3VCC(A), the port B pull-down driver is turned off and the external pull-up resistor pulls

the pin HIGH. When port B falls first and goes below 0.4 V the port A driver is turned on

and port A pulls down to 0 V. The port A pull-down is not enabled unless the port B

voltage goes below 0.4 V. If the port B low voltage goes below 0.4 V, the port B pull-down

driver is enabled and port B will only be able to rise to 0.5 V until port A rises above

0.3VCC(A), then port B will continue to rise being pulled up by the external pull-up resistor.

The VCC(A) is only used to provide the 0.3VCC(A) reference to the port A input comparators

and for the power good detect circuit. The PCA9517A logic and all I/Os are powered by

the VCC(B) pin.

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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