±10kV ESD-Protected, Quad 5V RS-485/RS-422

Transmitters

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7

Detailed Description

The MAX3040–MAX3045 are quad RS-485/RS-422 trans-

mitters. They operate from a single +5V power supply

and are designed to give optimum performance when

used with the MAX3093E/MAX3095 5V quad RS-485/

RS-422 receivers or MAX3094E/MAX3096 3V quad

RS-485/RS-422 receivers. The MAX3040–MAX3045 only

need 1mA of operating supply current and consume 2nA

when they enter a low-power shutdown mode. The

MAX3040–MAX3045 also feature a hot-swap capability

allowing line insertion without erroneous data transfer.

The MAX3042B/MAX3045B are capable of transferring

data up to 20Mbps, the MAX3041/MAX3044 for data

rates up to 2.5Mbps, and the MAX3040/MAX3043 for

data rates up to 250kbps. All transmitter outputs are pro-

tected to ±10kV using the Human Body Model.

±10kV ESD Protection

As with all Maxim devices, ESD-protection structures

are incorporated on all pins to protect against electro-

static discharges (ESD) encountered during handling

and assembly. The MAX3040–MAX3045 transmitter

outputs have extra protection against electrostatic dis-

charges found in normal operation. Maxim’s engineers

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

these pins against the application of ±10kV ESD

(Human Body Model), without damage.

ESD Test Conditions

ESD performance depends on a number of conditions.

Contact Maxim for a reliability report that documents

test setup, methodology, and results.

Human Body Model

Figure 6a shows the Human Body Model, and Figure

6b shows the current waveform it generates when dis-

charged into low impedance. This model consists of a

100pF capacitor charged to the ESD voltage of interest,

which is then discharged into the device through a

1.5k

Ω resistor.

R

R

Y

Z

Figure 1. Driver DC Test Circuit

DI

DE

5V

Y

Z

Figure 2. Driver Timing Test Circuit

DI

3V

0

Z

Y

0

1.5V

10%

90%

90%

1.5V

10%

Figure 3. Driver Propagation Delays

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

3V

0

Y, Z

Y, Z

0

1.5V

1.5V

2.5V

2.5V

DE

Figure 5. Driver Enable and Disable Times

OUTPUT

UNDER TEST

S1

S2

Figure 4. Driver Enable/Disable Timing Test Load