Applications Information

Differential Interface

The impedances of the differential interface are made

up of the two source resistors on the driver (MAX9546)

Circuit. These resistors are chosen so their sum match-

transmission line. For example, a Category 5 cable has

a characteristic impedance of 110Ω, so the sum of the

the line. To balance the signals they must be equal, so

±15kV ESD Protection

As with all Maxim devices, ESD-protection structures

are incorporated on all pins to protect against electro-

static discharges encountered during handling and

assembly. The driver outputs and receiver inputs have

extra protection against static electricity. Maxim’s engi-

neers developed state-of-the-art structures to protect

these pins against ESD of ±15kV without damage. The

ESD structures withstand high ESD in all states: normal

operation and powered down. After an ESD event, the

MAX9546/MAX9547 keep working without latchup. ESD

protection can be tested in various ways; the driver out-

puts and receiver inputs of this product family are char-

acterized for protection to ±15kV using the Human

Body Model. Other ESD test methodologies include IEC

1000-4-2 Contact Discharge and IEC 1000-4-2 Air-Gap

Discharge (formerly IEC 801-2).

ESD Test Conditions

ESD performance depends on a variety of conditions.

Contact Maxim for a reliability report that documents

test setup, test methodology, and test results.

Human Body Model

Figure 2 shows the Human Body Model, and Figure 3

shows the current waveform it generates when dis-

charged into a low impedance. This model consists of

a 100pF capacitor charged to the ESD voltage of inter-

est, which is then discharged into the test device

through a 1.5kΩ resistor.

Differential Video Interface Chipset

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9

Figure 2. Human Body ESD Test Model

CHARGE-CURRENT-

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

Cs

100pF

1MΩ

1.5kΩ

HIGH-

VOLTAGE

DC

SOURCE

DEVICE

UNDER

TEST

Figure 3. Human Body Current Waveform

90%

36.8%

TIME

CURRENT WAVEFORM

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

Ir

10%

0

0

AMPERES