6

FN6975.0

November 19, 2009

CML Input and Output Buffers

The input and output buffers for the high-speed data

channel in the ISL35111 are implemented using CML.

Equivalent input and output circuits are shown in

Figures 6 and 7.

Adjustable De-Emphasis

ISL35111 features a settable de-emphasis driver for

custom signal restoration.

The connectivity of the DE pins are used to determine the

boost de-emphasis level of ISL35111. Table 1 defines the

mapping from the 2-bit non-binary DE word to the 7

available output de-emphasis levels.

Disable Pin

The disable (TDSBL) pin is used to disable the driver

output in order to implement TX_Disable functions of

such industry standards as SFP+ and QSFP. When this

pin is pulled HIGH, the ISL35111 will enter a low-power

standby mode. For active data transmission, this pin

must be pulled LOW.

Line Silence/Quiescent Mode

The ISL35111 is capable of maintaining periods of line

silence by monitoring its input pins for loss of signal

(LOS) conditions and subsequently muting the output

driver when such a condition is detected. A reference

voltage applied to the detection threshold (DT) pin is

used to set the LOS threshold of the internal signal

detection circuitry. For most applications, it is

recommended to leave the DT pin floating at its default

internal bias. If the sensitivity of the detection threshold

needs to be adjusted, the DT voltage can be adjusted

with an external pull-up resistor. The resistor values

should be validated on an application-specific basis.

Connect the DT pin to ground in order to disable this

feature and prevent the outputs from muting during line

silence.

Intersil has long realized that to enable the complex

server clusters of next generation datacenters, it is

critical to manage the signal integrity issues of electrical

interconnects. To address this, Intersil has developed its

its analog ICs inside cabling interconnects, Intersil is able

to achieve unsurpassed improvements in reach, power

consumption, latency, and cable gauge size as well as

increased airflow in tomorrow's datacenters. This new

technology transforms passive cabling into intelligent

"roadways" that yield lower operating expenses and

capital expenditures for the expanding datacenter.

Intersil Lane Extenders allow greater reach over existing

cabling while reducing the need for thicker cables. This

significantly reduces cable weight and clutter, increases

airflow, and improves power consumption.

FIGURE 6. CML INPUT EQUIVALENT CIRCUIT FOR THE

ISL35111

FIGURE 7. CML OUTPUT EQUIVALENT CIRCUIT FOR

THE ISL35111

IN[P]

IN[N]

1

Stage

50O

50O

2kO

10kO

Ω

Ω

Ω

Ω

50O

50O

OUT[P]

OUT[N]

Ω

Ω

TABLE 1. MAPPING BETWEEN DE-EMPHASIS LEVEL

AND DE-PIN CONNECTIVITY

DE PIN

CONNECTION

NOMINAL

DE-EMPHASIS LEVEL;

10.3125Gbps TO

11.1Gbps (dB)

DE-EMPHASIS

SETTING

DE[A]

DE[B]

Open

Open

0

0

Open

GND

0.6

1

Open

VDD

1.1

2

GND

Open

1.6

3

GND

GND

2.3

4

GND

VDD

3

5

VDD

Open

4

6

ISL35111