ST ST3222EB, ST3222EC User Manual

low power, up to 250 Kbps, RS-232 drivers and receivers

Features

■ ESD protection for RS-232 I/O pins ± 15 kV

human body model, ± 8 kV IEC 1000-4-2
contact discharge

■ 300 µA supply current

■ 250KBps minimum guarantee data rate

■ 6 V/µs minimum guarantee slew rate

■ Meet EIA/TIA-232 specification down to 3 V

■ Available in SSOP20 and TSSOP20

ST3222EB
ST3222EC

± 15 kV ESD protected, 3 to 5.5 V

TSSOP

SSOP

Description

The ST3222E is a 3 V powered EIA/TIA-232 and
V.28/V.24 communications interface with low
power requirements, high data-rate capabilities
and enhanced electrostatic discharge (ESD)
protection to ± 8 kV using IEC1000-4-2 Contact
Discharge and ±15 kV using the Human Body
Model. ST3222E has a proprietary low dropout
transmitter output stage providing true RS-232
performance from 3 to 5 V supplies with a dual
charge pump. The charge pump requires only four
small 0.1 mF external capacitors for operation
form 3 V supply. The device has two receivers and
two drivers. The ST3222E features a 1 mA
shutdown mode that reduces power consumption
and extends battery life in portable systems. Its
receivers can remain active in shutdown mode,
allowing external devices such as modems to be
monitored using only 1 mA supply current. The
device is guaranteed to run at data rates of 250
Kbps while maintaining RS-232 output levels.

Table 1. Device summary

Order codes

Temperature

range

Package Packaging

Typical applications are Notebook, Sub-notebook
and Palmtop Computers, Battery Powered
Equipment, Hand-Held Equipment, Peripherals
and Printers.

ST3222ECPR 0 to 70 °C SSOP20 (tape and reel) 1350 parts per reel

ST3222EBPR -40 to 85 °C SSOP20 (tape and reel) 1350 parts per reel

ST3222ECTR 0 to 70 °C TSSOP20 (tape and reel) 2500 parts per reel

ST3222EBTR -40 to 85 °C TSSOP20 (tape and reel) 2500 parts per reel

January 2008 Rev 8 1/15

www.st.com

15

Contents ST3222E

Contents

1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Application circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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ST3222E Pin configuration

1 Pin configuration

Figure 1. Pin connection

Table 2. Pin description

Pin n° Symbol Name and function

1EN

2C

1

Receiver enable control. drive low for normal operation. Drive high to force the
receivers outputs (R_OUT) into a high-impedance state.

+ Positive terminal for the first charge pump capacitor

3 V+ 5.5V Generated by the charge pump.

4C

5C

6C

- Negative terminal for the first charge pump capacitor

1

+ Positive terminal for the second charge pump capacitor

2

- Negative terminal for the second charge pump capacitor

2

7 V- -5.5V Generated by the charge pump.

8T2

OUT

9R2

10 R2

OUT

Second transmitter output voltage

Second receiver input voltage

IN

Second receiver output voltage

11 NC Not connected

12 T2

13 T1

Second transmitter input voltage

IN

First transmitter input voltage

IN

14 NC Not connected

15 R1

16 R1

17 T1

OUT

OUT

First receiver output voltage

First receiver input voltage

IN

First transmitter output voltage

18 GND Ground

19 V

CC

Supply voltage

20 SHDN Active low shutdown control input. drive low to shut-down transmitter and charge pump

3/15

Absolute maximum ratings ST3222E

2 Absolute maximum ratings

Table 3. Absolute maximum ratings

Symbol Parameter Value Unit

V

CC

V+ Doubled voltage terminal (V

V- Inverted voltage terminal 0.3 to -7 V

V+ +|V-| 13 V

T

IN

R

IN

T

OUT

R

OUT

t

SHORT

Supply voltage -0.3 to 6 V

- 0.3) to 7 V

CC

Transmitter input voltage range -0.3 to 6 V

Receiver input voltage range ± 25 V

Transmitter output voltage range ± 13.2 V

Receiver output voltage range -0.3 to (VCC + 0.3) V

Transmitter output short to gnd time Continuous

Note: Absolute maximum ratings are those values beyond which damage to the device may

occur. Functional operation under these condition is not implied.

Externally applied V+ and V- can have a maximum magnitude of +7 V, but their absolute
addition can not exceed 13 V.

Running on internal charge pump, intrinsic self limitation allows exceeding those values
without any damage.

Startup voltage sequence (V

, then V+, then V-) is critical, therefore it is not recommended

CC

to use this device using externally applied voltage to V+ and V-.

Table 4. Shutdown and enable control truth table

SHDN EN T-OUT R-OUT

0 0 High Z Active

0 1 High Z High Z

1 0 Active Active

1 1 Active High Z

Table 5. ESD performance: transmitter outputs, receiver inputs

Symbol Parameter Test conditions Min. Typ. Max. Unit

ESD ESD protection voltage Human body model ±15 kV

ESD ESD protection voltage IEC-1000-4-2 ±8kV

4/15

ST3222E Electrical characteristics

3 Electrical characteristics

Table 6. Electrical characteristics (C

otherwise specified. Typical values are referred to T

- C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless

1

= 25 °C)

A

Symbol Parameter Test conditions Min. Typ. Max. Unit

I

SUPPLYVCC

I

SHDN

power supply current No load, SHDN = VCC, TA = 25°C 0.3 1 mA

Shutdown supply current No load, SHDN = VCC, TA = 25°C 1 10 µA

Table 7. Logic input electrical characteristics (C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V,

T

= -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C)

A

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

Input logic threshold low T-IN, EN, SHDN (Note: 1)0.8V

IL

VCC = 3.3 V 2

V

V

HYS

I

Input logic threshold high

IH

Transmitter input
hysteresis

Input leakage current T-IN, EN, SHDN ± 0.01 ± 1µA

IL

= 5 V 2.4

V

CC

0.25 V

Note: 1 Transmitter input hysteresis is typically 250 mV

Table 8. Transmitter electrical characteristics (C1 - C4 = 0.1 µF VCC = 3 V to 5.5 V,

T

= -40 to 85 °C, unless otherwise specified. Typical values are referred to TA = 25 °C)

A

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

V

R

I

TOUT

TOUT

TSC

I

TOL

Output voltage swing

Transmitter output
resistance

Output short circuit
current

Output leakage current

All transmitter outputs are loaded with
3 KΩ to GND

V

= V+ = V- = 0 V, V

CC

= 0 or 3 V to 3.6 V, V

V

CC

= ± 2 V 300 10M Ω

OUT

= ± 12 V

OUT

Transmitters disable

± 5 ± 5.4 V

± 60 mA

± 25 µA

5/15