PCA9507_1

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 01 — 7 February 2008

5 of 20

NXP Semiconductors

PCA9507

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.

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 k

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

pull-up resistor is 47 k

Ω on the SCLA line, and there is no pull-up on the SDAA line.

Please refer to Table 3, Figure 7 and Figure 8 for more details. Figure 5 shows the port A

pull-up resistor values (in k

Ω) versus capacitance load (in nF) for 5 V supply voltage

complied with 1

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.

Table 3.

HDMI DDC pull-up resistors specification

Pin

Where

Minimum

Maximum

SDAA

at the source (DVD/STB)

1.5 k

Ω

2.0 k

Ω

at the sink (LCD TV)

-

-

SCLA

at the source (DVD/STB)

1.5 k

Ω

2.0 k

Ω

at the sink (LCD TV)

47 k

Ω± 10 %

rise time = 1

µs; V

Fig 5.

SDAA/SCLA line pull-up resistor versus load capacitance

0

4.0

3.0

2.0

1.0

002aad620

4.5

6.5

2.5

8.5

10.5

(k

Ω)

0.5

does not comply with

1

µs rise time

complies with

1

µs rise time