PCA9527DP 데이터 시트보기 (PDF) - NXP Semiconductors.

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PCA9527DP

3-channel bidirectional bus extender for HDMI, I2C-bus and SMBus

NXP Semiconductors. 

NXP Semiconductors

PCA9527

3-channel bidirectional bus extender for HDMI, I2C-bus and SMBus

Table 2.

Symbol

GND

EN

CECB

SDAB

SCLB

VCC(B)

Pin description …continued

Pin Description

5

supply ground (0 V)

6

active HIGH buffer enable input

7

serial data with static level offset, powered by VCC(B), 5 V tolerant

8

serial data port B bus with static level offset, 5 V tolerant

9

serial clock port B bus with static level offset, 5 V tolerant

10 port B supply voltage (2.7 V to 3.6 V)

6. Functional description

Refer to Figure 1 “Functional diagram of PCA9527”.

The PCA9527 consists of 3 channels of bidirectional open-drain I/Os specifically designed

to support up-translation/down-translation between low voltages (as low as 2.7 V) and a

3.3 V or 5 V I2C-bus and SMBus. The device contains a rise time accelerator, specifically

on port A of the SCLA and SDAA that enables the device to drive a long cable or a heavier

capacitive load for DDC, I2C-bus and SMBus applications. With dual supply rails, the

device translates from voltage ranges 2.7 V to 5.5 V down to a voltage as low as 2.7 V

without degradation of system performance. Unlike the SDAA and SCLA, the CECA is

powered by the VCC(B) and does not have a rise time accelerator, but is similar in that its

port A has normal I/O and port B static level offset. All I/Os are overvoltage tolerant to

5.5 V even when the device is un-powered (VCC(B) and/or VCC(A) = 0 V).

The PCA9527 includes a power-up circuit that keeps the SDA and SCL output drivers

turned off until VCC(A) and VCC(B) rise above 2.7 V. The CECA output drivers are turned

OFF until VCC(B) rises above 2.7 V. VCC(A) and VCC(B) can be applied in any sequence at

power-up.

PCA9527_1

Product data sheet

VCC(B)

0.3VCC(B)

port B

0.4 V

VCC(A)

0.3VCC(A)

port A

0.5 V

0V

0.7VCC(A)

0V

002aad435

Fig 3. Port A and port B I/O levels

When port B falls first and goes below 0.3VCC(B) the port A driver is turned on and port A

pulls down to 0 V. As port A falls below 0.3VCC(A) the port B pulls down to about 0.5 V.

The external port B driver must drive the port B to a LOW that is ≤ 0.4 V or else it is not

possible to know who is driving the port A LOW. The PCA9527 direction control assumes

that port A is controlling the part unless port B falls below 0.4 V. When the port B voltage

is ≤ 0.4 V the port A driver of the PCA9527 is on and holds port A down to nearly 0 V. As

the port B voltage rises because the external driver turns off, the port B voltage rises up to

~0.5 V because port A is LOW; once port B rises to ~0.5 V the port A pull-down driver

turns off. Then port A rises with a rise time determined by the RC of port A when it

Rev. 01 — 29 June 2009

© NXP B.V. 2009. All rights reserved.

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