MAX3385E

5k

R_ IN

R_ OUT

C2-

C2+

C1-

C1+

V-

V+

C4

C3

C1

C2

0.1

µF

SHDN

T_ OUT

T_ IN

GND

1000pF

Figure 6. Loopback Test Circuit

2

µs/div

T1IN

T1OUT

R1OUT

5V/div

5V/div

5V/div

C1–C4 = 0.1

µF

Figure 7. MAX3385E Loopback Test Result at 120kbps

2

µs/div

T1IN

T1OUT

R1OUT

5V/div

5V/div

5V/div

C1–C4 = 0.1

µF

Figure 8. MAX3385E Loopback Test Result at 250kbps

±15kV ESD-Protected, 3.0V to 5.5V, Low-Power,

up to 250kbps, True RS-232 Transceiver

8

_______________________________________________________________________________________

els (one transmitter input is high, the other is low). Each

transmitter is loaded with 3k

Ω in parallel with 2500pF.

The transmitter outputs display no ringing or undesir-

able transients as they come out of shutdown. Note that

the transmitters are enabled only when the magnitude

of V- exceeds approximately -3V.

High Data Rates

The MAX3385E maintains the RS-232 ±5.0V minimum

transmitter output voltage even at high data rates.

Figure 6 shows a transmitter loopback test circuit.

Figure 7 shows a loopback test result at 120kbps, and

Figure 8 shows the same test at 250kbps. For Figure 7,

all transmitters were driven simultaneously at 120kbps

into RS-232 loads in parallel with 1000pF. For Figure 8,

a single transmitter was driven at 250kbps, and all

transmitters were loaded with an RS-232 receiver in

parallel with 1000pF.

Interconnection with 3V and 5V Logic

The MAX3385E can directly interface with various 5V

logic families, including ACT and HCT CMOS. See

Table 3 for more information on possible combinations

of interconnections.