MAX14984 Datasheet, PDF(10/12 Page) Maxim Integrated Products – Enhanced VGA Port Protector with Monitor Detection and Dual USB Power Switches

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MAX14984

Enhanced VGA Port Protector with Monitor

Detection and Dual USB Power Switches

Monitor Detection and

Automatic Switching

The MAX14984 detects monitor insertion/removal events

by measuring the voltage on B1. The monitor detection

circuitry always correctly indicates the presence of a

monitor as long as V0 is not high impedance. The volt-

age measurement is only sampled between synchroniza-

tion pulses on V0 from the controller when a monitor is

inserted to ensure that the video signal is not interrupted

while promptly detecting a removal.

The device automatically connects the graphics control-

ler to the monitor when it is plugged in if configured in

automatic mode. To configure automatic mode, connect

MD to ENV and add a pullup resistor.

Applications Information

Compatibility with Low-Voltage

Graphics Controllers

The MAX14984 provides the level shifting necessary to

drive a standard VGA port using any graphics controller.

Internal buffers drive the H and V signals to VGA stand-

ard TTL levels. The DDC switches provide level shifting

by limiting signal levels that can be passed through the

DDC switches to less than 2.5V. Add pullup resistors

from the DDC lines to the graphics controller supply to

set the logic level on the SDA0/SCL0 side.

Power-Supply Decoupling

Bypass VCC to ground with a 1FF or larger ceramic

capacitor as close to the device as possible.

PC Board Layout

High-speed switches such as the MAX14984 require

proper PCB layout for optimum performance. Ensure that

impedance-controlled PCB traces for high-speed signals

are matched in length and as short as possible. Connect

the exposed pad to a solid ground plane.

High ESD Protection

Electrostatic Discharge (ESD) protection structures are

incorporated on all pins to protect against electrostatic

discharges up to Q2kV Human Body Model (HBM)

encountered during handling and assembly. All VGA

and USB outputs are further protected against ESD up to

Q8kV (HBM) without damage (see the Pin Description).

The ESD structures withstand high ESD both in normal

operation and when the device is powered down. After

an ESD event, the MAX14984 continues to function with-

out latchup.

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 3 shows the Human Body Model. Figure 4 shows

the current waveform it generates when discharged

into a low impedance. This model consists of a 100pF

capacitor charged to the ESD voltage of interest that is

then discharged into the device through a 1.5kI resistor.

1Mâ¦

1.5kâ¦

CHARGE-CURRENT- DISCHARGE

LIMIT RESISTOR

RESISTANCE

HIGH-

VOLTAGE

SOURCE

100pF

STORAGE

CAPACITOR

Figure 3. Human Body ESD Test Model

DEVICE

UNDER

TEST

IPEAK (AMPS)

100%

90%

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

36.8%

10%

TIME

0 tRL

tDL

Figure 4. Human Body Current Waveform

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