PCA9517 datasheet(3/19 Pages) NXP

3 / 19 page

PCA9517_3

Product data sheet

Rev. 03 — 30 January 2007

3 of 19

NXP Semiconductors

PCA9517

Level translating I2C-bus repeater

Pinning information

5.1 Pinning

5.2 Pin description

Functional description

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

Fig 2.

Pin conﬁguration for SO8

Fig 3.

Pin conﬁguration for TSSOP8

(MSOP8)

PCA9517D

VCCA

VCCB

SCLA

SCLB

SDAA

SDAB

GND

002aac198

PCA9517DP

VCCA

VCCB

SCLA

SCLB

SDAA

SDAB

GND

002aac199

Table 2.

Pin description

Symbol

Description

VCCA

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

SCLA

serial clock A-side bus

SDAA

serial data A-side bus

GND

supply ground (0 V)

active HIGH repeater enable input

SDAB

serial data B-side bus

SCLB

serial clock B-side bus

VCCB

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

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