PCA9527DP 데이터 시트보기 (PDF) - NXP Semiconductors.

부품명

상세내역

제조사

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

crosses the port A threshold ~0.3VCC(A) the port B driver is turned off and the rising edge

accelerator is turned on, which causes a faster rising edge until it reaches the turn-off

point for the rising edge accelerator ~0.7VCC(A). Then it continues to rise at the slower rate

determined by the RC of port A. When the port B driver turns off, port B rises with the RC

of port B.

VCC(A) powers the 0.3VCC(A) reference for SCLA and SDAA as well as the port A power

good detect circuit. VCC(B) powers the rest of the chip including the port B I/Os, the CEC

I/Os, and the support functions. Figure 3 illustrates the threshold and I/O levels for port A

and port B.

6.1 Enable

The EN pin is active HIGH with an internal ~100 kΩ pull-up to VCC(B) and allows the user

to select when the buffer is active. The enable pin puts the PCA9527 in a power-down

state when it is disabled, so that there is a recovery delay and a lower power-down power.

This can be used to isolate the line when the HDMI DDC transmitter or receiver is not

ready, or from 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 buffer port are in an idle state to prevent system failures.

6.2 Rise time accelerators

PCA9527 has rise time accelerators on port A of SCL and SDA only; the CECA pin does

not have a rise time accelerator. During port A positive bus transitions a current source is

switched on to quickly slew the SDAA and SCLA lines HIGH once the input level of

0.3VCC(A) is exceeded for the PCA9527 and turns off as the 0.7VCC(A) voltage is

approached.

6.3 Resistor pull-up value selection

6.3.1 Port A (SDAA and SCLA)

SDAA and SCLA are open-drain I/O that have rise time accelerators and strong pull-down.

When the inputs transition above 0.3VCC(A), the rise time accelerator activates and boosts

the pull-up current during rising edge to meet the I2C-bus rise time specification when the

device drives a long cable or heavier capacitance load. The strong pull-down enables the

output to drive to nearly zero voltage for logic LOW. The selection for pull-up resistors are

defined in the HDMI DDC specification shown in Table 3. For HDMI transmitter

applications like digital video player, recorder, or set-top box, the pull-up resistor is in the

range of 1.5 kΩ to 2 kΩ. For HDMI receiver applications like in LCD TV or video card, the

pull-up resistor is 47 kΩ on the SCLA line, and there is no pull-up on the SDAA line.

Please refer to Table 3, Figure 6 and Figure 7 for more details. Figure 4 shows the port A

pull-up resistor values (in kΩ) versus capacitance load (in nF) for 5 V supply voltage

complied with 1 µs rise time per I2C-bus Standard-mode specification. The graph

contrasts a shaded and unshaded region. Any resistor value chosen within the unshaded

region would comply with 1 µs rise time, while any value chosen in the shaded region

would not.

PCA9527_1

Product data sheet

Rev. 01 — 29 June 2009

© NXP B.V. 2009. All rights reserved.

5 of 22

Share Link: