PCA9517 查看數據表（PDF） - NXP Semiconductors.

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PCA9517

Level translating I2C-bus repeater

NXP Semiconductors. 

NXP Semiconductors

5. Pinning information

5.1 Pinning

PCA9517

Level translating I2C-bus repeater

VCCA 1

SCLA 2

SDAA 3

GND 4

8 VCCB

7 SCLB

PCA9517D

6 SDAB

5 EN

002aac198

Fig 2. Pin configuration for SO8

VCCA 1

SCLA 2

SDAA 3

GND 4

PCA9517DP

8 VCCB

7 SCLB

6 SDAB

5 EN

002aac199

Fig 3. Pin configuration for TSSOP8

(MSOP8)

5.2 Pin description

Table 2.

Symbol

VCCA

SCLA

SDAA

GND

EN

SDAB

SCLB

VCCB

Pin description

Pin

1

2

3

4

5

6

7

8

Description

A-side supply voltage (0.9 V to 5.5 V)

serial clock A-side bus

serial data A-side bus

supply ground (0 V)

active HIGH repeater enable input

serial data B-side bus

serial clock B-side bus

B-side supply voltage (2.7 V to 5.5 V)

6. Functional description

PCA9517_3

Product data sheet

Refer to Figure 1 “Functional diagram of PCA9517”.

The PCA9517 enables I2C-bus or SMBus translation down to VCCA as low as 0.9 V

without degradation of system performance. The PCA9517 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 (VCCB

and/or VCCA = 0 V). The PCA9517 includes a power-up circuit that keeps the output

drivers turned off until VCCB is above 2.5 V and the VCCA is above 0.8 V. VCCB and VCCA

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

HIGH, a LOW level on the A-side (below 0.3VCCA) turns the corresponding B-side driver

(either SDA or SCL) on and drives the B-side down to about 0.5 V. When the A-side rises

above 0.3VCCA the B-side pull-down driver is turned off and the external pull-up resistor

pulls the pin HIGH. When the B-side falls first and goes below 0.3VCCB the A-side driver is

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

the B-side voltage goes below 0.4 V. If the B-side low voltage does not go below 0.5 V, the

A-side driver will turn off when the B-side voltage is above 0.7VCCB. If the B-side low

voltage goes below 0.4 V, the B-side pull-down driver is enabled and the B-side will only

Rev. 03 — 30 January 2007

© NXP B.V. 2007. All rights reserved.

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