3

Pin Descriptions

PIN

FUNCTION

System power supply input (2.7V to 5.5V).

V+

Internally generated positive transmitter supply (+5.5V).

V-

Internally generated negative transmitter supply (-5.5V).

GND

Ground connection.

C1+

External capacitor (voltage doubler) is connected to this lead.

C1-

External capacitor (voltage doubler) is connected to this lead.

C2+

External capacitor (voltage inverter) is connected to this lead.

C2-

External capacitor (voltage inverter) is connected to this lead.

TTL/CMOS compatible transmitter Inputs. (Note 1)

TTL/CMOS level receiver outputs.

TTL/CMOS level, noninverting, always enabled receiver outputs.

INVALID

Active low output that indicates if no valid RS-232 levels are present on any receiver input.

FORCEOFF Active low to shut down transmitters and on-chip power supply. This overrides any automatic circuitry and FORCEON (see Table 2).

FORCEON

Active high input to override automatic powerdown circuitry thereby keeping transmitters active. (FORCEOFF must be high).

NOTE:

1. ISL4238E input pins incorporate positive feedback resistors. Once the input is driven to a valid logic level, the feedback resistor maintains that

ISL4238E, ISL4244E, ISL4245E