5

Detailed Description

The ISL83220E operates from a single +3V to +5.5V supply,

guarantees a 250kbps minimum data rate, requires only four

small external 0.1

μF capacitors, features low power

consumption, and meets all ElA RS-232C and V.28

specifications. The circuit is divided into three sections: The

charge pump, the transmitter, and the receiver.

Charge-Pump

Intersil’s new 3.3V family utilizes regulated on-chip dual

charge pumps as voltage doublers, and voltage inverters to

generate

low as 3.0V. This allows 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 0.1

μF capacitors for the

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.

The transmitter output disables and assumes a high

impedance state when the device enters the powerdown

mode (see Table 2). This output may be driven to

±12V when

disabled.

All devices guarantee a 250kbps data rate for full load

conditions (3k

Ω and 1000pF), V

the ISL83220E easily operates at 900kbps.

Transmitter inputs float if left unconnected, and may cause

Receivers

The ISL83220E device contains a standard inverting

receiver that three-states via the EN control line. 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

hysteresis to increase noise immunity and decrease errors

due to slow input signal transitions.

TIMING CHARACTERISTICS

Maximum Data Rate

Full

250

500

-

kbps

Transmitter Propagation Delay

Transmitter Input to

Transmitter Output,

25

-

1.0

-

μs

25

-

1.0

-

μs

Receiver Propagation Delay

Receiver Input to Receiver

25

-

0.20

-

μs

25

-

0.30

-

μs

Receiver Output Enable Time

Normal Operation

25

-

200

-

ns

Receiver Output Disable Time

Normal Operation

25

-

200

-

ns

Transmitter Skew

25

-

100

500

ns

Receiver Skew

Full

-

100

1000

ns

Transition Region Slew Rate

Measured From 3V to -3V or

-3V to 3V

25

4

-

30

V/

μs

25

6

-

30

V/

μs

ESD PERFORMANCE

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

-

±3-

kV

NOTE:

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

Electrical Specifications

PARAMETER

TEST CONDITIONS

TEMP

(°C)

MIN

TYP

MAX

UNITS

ISL83220E