ICL3221E, ICL3222E, ICL3223E, ICL3232E, ICL3241E, ICL3243E

FN4910 Rev 22.00

Page 14 of 33

December 9, 2015

Detailed Description

ICL32xxE interface ICs operate from a single +3V to

+5.5V supply, guarantee a 250kbps minimum data

rate, require only four small external 0.1µF capacitors,

feature low power consumption, and meet all ElA

RS-232C and V.28 specifications. The circuit is divided

into three sections: charge pump, transmitters and

receivers.

Charge-Pump

Intersil’s new ICL32xxE family utilizes regulated on-

chip dual charge pumps as voltage doublers, and

voltage inverters to generate ±5.5V transmitter

these devices to maintain RS-232 compliant output

levels over the ±10% tolerance range of 3.3V powered

systems. The efficient on-chip power supplies require

only four small, external 0.1µF capacitors for the

See “Capacitor Selection” on page 18 and Table 3 on

page 18 for capacitor recommendations for other

operating conditions. The charge pumps operate

discontinuously (i.e., they turn off as soon as the V+

and V- supplies are pumped up to the nominal values),

resulting in significant power savings.

Transmitters

The transmitters are proprietary, low dropout, inverting

drivers that translate TTL/CMOS inputs to EIA/TIA-232

output levels. Coupled with the on-chip ±5.5V

supplies, these transmitters deliver true RS-232 levels

over a wide range of single supply system voltages.

Except for the ICL3232E, all transmitter outputs

disable and assume a high impedance state when the

device enters the power-down mode (see Table 2).

These outputs may be driven to ±12V when disabled.

All devices guarantee a 250kbps data rate for full load

transmitter operating at full speed. Under more typical

one transmitter easily operates at 900kbps.

Transmitter inputs float if left unconnected, and may

the best performance.

Receivers

All the ICL32xxE devices contain standard inverting

receivers that three-state (except for the ICL3232E)

via the EN or FORCEOFF control lines. Additionally, the

two ICL324XE products include noninverting

(monitor) receivers (denoted by the ROUTB label)

that are always active, regardless of the state of any

control lines. All the receivers convert RS-232 signals

to CMOS output levels and accept inputs up to ±25V

while presenting the required 3kΩ to 7kΩ input

impedance (see Figure 1) even if the power is off

(VCC = 0V). The receivers’ Schmitt trigger input stage

uses hysteresis to increase noise immunity and

decrease errors due to slow input signal transitions.

The ICL3221E, ICL3222E, ICL3223E, ICL3241E

inverting receivers disable only when EN is driven high.

ICL3243E receivers disable during forced (manual)

power-down, but not during automatic power-down

(see Table 2).

Receiver Output Disable

Time

Normal Operation (Except ICL3232E)

25

-

200

-

ns

Transmitter Skew

25

-

100

-

ns

Receiver Skew

25

-

50

-

ns

Measured from 3V to

-3V or -3V to 3V

25

4

-

30

V/µs

25

6

-

30

V/µs

ESD PERFORMANCE

RS-232 Pins (TOUT, RIN)

Human Body Model

25

-

15

-

kV

IEC61000-4-2 Contact Discharge

25

-

8-

kV

IEC61000-4-2 Air Gap Discharge

25

-

15

-

kV

All Other Pins

Human Body Model

25

-

2-

kV

NOTES:

5. Transmitter skew is measured at the transmitter zero crossing points.

6. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established

by characterization and are not production tested.

range. (Continued)

PARAMETER

TEST CONDITIONS

TEMP

(°C)

MIN

(Note 6)

TYP

MAX

(Note 6) UNITS