11

FN8037.7

June 10, 2010

Operation Down to 2.7V

The ISL4241E, ISL4243E transmitter outputs meet RS-562

RS-562 levels typically ensure inter operability with RS-232

devices.

High Data Rates

The ISL4241E, ISL4243E maintain the RS-232 ±5V

minimum transmitter output voltages even at high data rates.

Figure 9 details a transmitter loopback test circuit, and

Figure 10 illustrates the loopback test result at 120kbps. For

this test, all transmitters were simultaneously driving RS-232

loads in parallel with 1000pF, at 120kbps. Figure 11 shows

the loopback results for a single transmitter driving 1000pF

and an RS-232 load at 250kbps. The static transmitters were

also loaded with an RS-232 receiver.

Interconnection with 3V and 5V Logic

The ISL4241E, ISL4243E directly interface with 5V CMOS

and TTL logic families. Nevertheless, with the ISL4241E,

ISL4243E at 3.3V, and the logic supply at 5V, AC, HC, and

CD4000 outputs can drive ISL4241E, ISL4243E inputs, but

for these logic families. See Table 3 for more information.

FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT

TIME (20µs/DIV)

T1

T2

2V/DIV.

5V/DIV.

FORCEOFF

FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING

POWER-DOWN

C1 to C4 = 0.1µF

ISL4241E

FORCEOFF or SHDN

+

+

+

+

1000pF

V+

V-

5k

C1+

C1-

C2+

C2-

+

0.1µF

FORCEON

ISL4243E

FIGURE 10. LOOPBACK TEST AT 120kbps

FIGURE 11. LOOPBACK TEST AT 250kbps

TABLE 3.

LOGIC FAMILY COMPATIBILITY WITH VARIOUS

SUPPLY VOLTAGES

SYSTEM

POWER-SUPPLY

VOLTAGE

(V)

SUPPLY

VOLTAGE

(V)

COMPATIBILITY

3.3

3.3

Compatible with all CMOS

families.

5

5

Compatible with all TTL and

CMOS logic families.

5µs/DIV

5V/DIV

C1 to C4 = 0.1 µF

2µs/DIV

5V/DIV.

C1 - C4 = 0.µF

ISL4241E, ISL4243E