3

FN8038.5

May 13, 2010

Pinouts

ISL4238E

(32 LD QFN)

TOP VIEW

ISL4244E, ISL4245E

(32 LD QFN)

TOP VIEW

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. This is also the potential of the thermal pad (PD).

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)

±15kV ESD Protected

±15kV ESD Protected

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 power-down circuitry thereby keeping transmitters active. (FORCEOFF must be high).

NC

No Connection

PD

Exposed Thermal Pad. Connect to GND.

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

C1-

1

2

3

4

5

6

7

8

24

23

22

21

20

19

18

17

32

31

30

29

28

27

26

25

9

1011

12

13

1415

16

PD

C1-

FORCEON

FORCEOFF

INVALID

GND

1

2

3

4

5

6

7

8

24

23

22

21

20

19

18

17

32

31

30

29

28

27

26

25

9

1011

12

13

1415

16

PD

ISL4238E, ISL4244E, ISL4245E