ISL4221_技术文档

ISL4221E, ISL4223E

®

Data Sheet

August 2004

FN6045.1

QFN Packaged, +/-15kV ESD Protected,

+2.7V to +5.5V, 150Nanoamp, 250kBps,

RS-232 Transmitters/Receivers

Features

• Available in Near Chip Scale QFN (5mmx5mm) Package

which is 40% Smaller than a 20 Lead TSSOP

The Intersil ISL422XE devices are 2.7V to 5.5V powered

RS-232 transmitters/receivers which meet ElA/TIA-232 and

• ESD Protection for RS-232 I/O Pins to ±15kV (IEC61000)

• Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V

V.28/V.24 specifications, even at V

= 3.0V. Additionally,

CC

they provide ±15kV ESD protection (IEC61000-4-2 Air Gap,

and Human Body Model) on transmitter outputs and receiver

inputs (RS-232 pins). Targeted applications are PDAs,

Palmtops, and hand-held products where the low

operational, and even lower standby, power consumption is

critical. Efficient on-chip charge pumps, coupled with manual

and automatic powerdown functions, reduce the standby

supply current to a 150nA trickle. Tiny 5mm x 5mm Quad

Flat No-Lead (QFN) packaging and the use of small, low

value capacitors ensure board space savings as well. Data

rates greater than 250kBps are guaranteed at worst case

load conditions.

• RS-232 Compatible with V

= 2.7V

CC

• On-Chip Voltage Converters Require Only Four External

0.1µF Capacitors

• Manual and Automatic Powerdown Features

• Receiver Hysteresis For Improved Noise Immunity

• Guaranteed Minimum Data Rate . . . . . . . . . . . . 250kBps

• Wide Power Supply Range. . . . . . . Single +2.7V to +5.5V

• Low Supply Current in Powerdown State. . . . . . . . .150nA

• Pb-free Available as an Option

The ISL4221E is a 1 driver, 1 receiver device and the

ISL4223E is a 2 driver, 2 receiver device that, coupled with

the 5x5 QFN package, provide the industry’s smallest,

lowest power serial port suitable for PDAs, and hand-held

applications. The 5x5 QFN requires 40% less board area

than a 20 lead TSSOP, and is nearly 20% thinner.

Applications

• Any Space Constrained System Requiring RS-232 Ports

- Battery Powered, and Portable Equipment

- Hand-Held Products (GPS Receivers, Bar Code

Scanners, etc.)

- PDAs and Palmtops, Data Cables

The ISL422XE features an automatic powerdown function

that powers down the on-chip power-supply and driver

circuits. This occurs when an attached peripheral device is

shut off or the RS-232 cable is removed, conserving system

power automatically without changes to the hardware or

operating system. It powers up again when a valid RS-232

voltage is applied to any receiver input.

- Cellular/Mobile Phones, Digital Cameras

Related Literature

• Technical Brief TB363 “Guidelines for Handling and

Processing Moisture Sensitive Surface Mount Devices

• ”Technical Brief TB379 “Thermal Characterization of

Packages for ICs”

Table 1 summarizes the features of the ISL422XE, while

Application Note AN9863 summarizes the features of each

device comprising the 3V RS-232 family.

• Technical Brief TB389 “PCB Land Pattern Design and

Surface Mount Guidelines for QFN Packages”

TABLE 1. SUMMARY OF FEATURES

PART

NUMBER

NO. OF NO.OF

QFN PKG.

AVAILABLE?

DATA RATE

(kBps)

Rx. ENABLE

FUNCTION?

MANUAL

POWERDOWN?

AUTOMATIC POWERDOWN

FUNCTION?

Tx.

Rx.

ISL4221E

ISL4223E

1

YES

250

YES

2

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc.

1

All other trademarks mentioned are the property of their respective owners.

ISL4221E, ISL4223E

Ordering Information

Ordering Information (Continued)

PART NO.

ISL4221EIR

ISL4221EIR-T

TEMP. RANGE (°C) PACKAGE PKG. DWG. #

PART NO.

TEMP. RANGE (°C) PACKAGE PKG. DWG. #

-40 to 85

16 Ld QFN L16.5x5

ISL4223EIR-T

-40 to 85

20 Ld QFN L20.5x5

Tape & Reel

16 Ld QFN L16.5x5

Tape & Reel

ISL4223EIRZ-T

(Note)

20 Ld QFN L20.5x5

Tape & Reel

ISL4221EIRZ-T

(Note)

-40 to 85

16 Ld QFN L16.5x5

Tape & Reel

(Pb-free)

NOTE: Intersil Pb-free products employ special Pb-free material

sets; molding compounds/die attach materials and 100% matte tin

plate termination finish, which is compatible with both SnPb and

Pb-free soldering operations. Intersil Pb-free products are MSL

classified at Pb-free peak reflow temperatures that meet or exceed

the Pb-free requirements of IPC/JEDEC J Std-020B.

ISL4223EIR

-40 to 85

20 Ld QFN L20.5x5

ISL4223EIRZ

(Note)

20 Ld QFN L20.5x5

(Pb-free)

Pinouts

ISL4221E (QFN)

ISL4223E (QFN)

TOP VIEW

16 15 14 13

20 19 18 17 16

V+

C1-

C2+

C2-

1

2

3

4

12 GND

11 T1

T1

15

14

V+

C1-

C2+

C2-

V-

1

2

3

4

5

OUT

R1

OUT

IN

10 FORCEON

13 R1

OUT

9

T1

IN

12 FORCEON

T1

5

6

7

8

11

IN

6

7

8

9

10

Pin Descriptions

FUNCTION

V

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

Internally generated positive transmitter supply (+5.5V).

Internally generated negative transmitter supply (-5.5V).

Ground connection.

CC

V+

V-

GND

C1+

C1-

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

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

TTL/CMOS compatible transmitter Inputs.

C2+

C2-

T

IN

T

±15kV ESD Protected, RS-232 level (nominally ±5.5V) transmitter outputs.

±15kV ESD Protected, RS-232 compatible receiver inputs.

TTL/CMOS level receiver outputs.

OUT

R

IN

R

OUT

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).

EN

Active low receiver enable control.

2

ISL4221E, ISL4223E

Typical Operating Circuits

ISL4221E

+3.3V

+

0.1µF

13

16

+

2

C

0.1µF

1

C1+

V

CC

1

C

0.1µF

3

+

V+

V-

C1-

3

C

0.1µF

2

C2+

+

5

C

4

0.1µF

4

C2-

+

T

1

9

7

11

T1

OUT

T1

R1

IN

TTL/CMOS

LOGIC

LEVELS

RS-232

LEVELS

6

R1

IN

OUT

5kΩ

R

1

15

10

EN

14

8

V

CC

FORCEOFF

INVALID

TO POWER

CONTROL LOGIC

FORCEON

GND

12

ISL4223E

17

+3.3V

+

0.1µF

20

C

0.1µF

C1+

1

V

CC

C

0.1µF

+

3

+

V+

V-

2

C1-

3

C

0.1µF

2

C2+

+

5

C

4

0.1µF

4

C2-

+

T

1

2

11

10

15

6

T1

T2

T1

T2

IN

OUT

IN

TTL/CMOS

RS-232

LOGIC LEVELS

13

14

7

LEVELS

R1

R2

R1

R2

OUT

IN

5kΩ

R

1

8

R

2

19

EN

18

9

V

FORCEOFF

INVALID

CC

12

TO POWER

CONTROL LOGIC

FORCEON

GND

16

3

ISL4221E, ISL4223E

Absolute Maximum Ratings

Thermal Information

o

V

to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V

Thermal Resistance (Typical, Note 1)

θ_JA( C/W)

CC

V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V

V- to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V

V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V

Input Voltages

16 Ld QFN Package. . . . . . . . . . . . . . . . . . . . . . . . .

20 Ld QFN Package. . . . . . . . . . . . . . . . . . . . . . . . .

Moisture Sensitivity (see Technical Brief TB363)

QFN Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1

Maximum Junction Temperature (Plastic Package) . . . . . . . 150 C

35

32

o

T

, FORCEOFF, FORCEON, EN . . . . . . . . . . . . . . . -0.3V to 6V

IN

o

R

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±25V

IN

Output Voltages

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±13.2V

Maximum Storage Temperature Range. . . . . . . . . . -65 C to 150 C

Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300 C

o

T

OUT

R

, INVALID. . . . . . . . . . . . . . . . . . . . . . . . -0.3V to V

+0.3V

OUT

CC

Operating Conditions

Short Circuit Duration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous

Temperature Range

ISL422XEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40 C to 85 C

T

OUT

ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table

o

CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the

device at these or any other conditions above those indicated in the operational sections of this specification is not implied.

NOTE:

1. θ is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See

JA

Tech Brief TB379, and Tech Brief TB389.

Electrical Specifications Test Conditions: V = 3V to 5.5V, C - C = 0.1µF; Unless Otherwise Specified.

CC

1

4

o

Typicals are at T = 25 C

A

TEMP

o

PARAMETER

TEST CONDITIONS

( C)

MIN

TYP

MAX

UNITS

DC CHARACTERISTICS

Supply Current, Automatic

Powerdown

All R Open, FORCEON = GND, FORCEOFF = V

IN

25

-

0.15

1

µA

CC

Supply Current, Powerdown

FORCEOFF = GND

25

-

0.15

0.3

1

µA

Supply Current,

All Outputs Unloaded,

V

= 3.15V

1.0

mA

CC

Automatic Powerdown Disabled

FORCEON = FORCEOFF = V

CC

LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS

Input Logic Threshold Low

Input Logic Threshold High

T

, FORCEON, FORCEOFF, EN

Full

-

2.0

2.4

-

0.8

-

V

IN

T

EN

, FORCEON, FORCEOFF,

V

= 3.3V

= 5.0V

-

CC

-

V

CC

Input Leakage Current

Output Leakage Current

Output Voltage Low

Output Voltage High

T

, FORCEON, FORCEOFF, EN

±0.01

±0.05

-

±1.0

±10

0.4

-

µA

V

IN

EN = V

-

CC

I

= 1.6mA

= -1.0mA

-

OUT

V

-0.6 V

-0.1

CC

V

CC

AUTOMATIC POWERDOWN (FORCEON = GND, FORCEOFF = V

)

CC

Receiver Input Thresholds to

Enable Transmitters

ISL422XE Powers Up (See Figure 6)

Full

-2.7

-0.3

-

2.7

0.3

V

Receiver Input Thresholds to

Disable Transmitters

ISL422XE Powers Down (See Figure 6)

-

INVALID Output Voltage Low

INVALID Output Voltage High

Receiver Threshold to Transmitters

I

= 1.6mA

= -1.0mA

Full

25

-

0.4

V

OUT

V

-0.6

-

CC

-

100

µs

Enabled Delay (t

)

WU

Receiver Positive or Negative

Threshold to INVALID High Delay

25

-

1

-

µs

(t

)

INVH

Receiver Positive or Negative

30

Threshold to INVALID Low Delay

(t

)

INVL

4

ISL4221E, ISL4223E

Electrical Specifications Test Conditions: V = 3V to 5.5V, C - C = 0.1µF; Unless Otherwise Specified.

CC

1

4

o

Typicals are at T = 25 C (Continued)

A

TEMP

o

PARAMETER

RECEIVER INPUTS

TEST CONDITIONS

( C)

MIN

TYP

MAX

UNITS

Input Voltage Range

Input Threshold Low

25

-25

0.6

0.8

-

25

-

V

= 3.3V

= 5.0V

= 3.3V

= 5.0V

1.2

1.5

1.8

0.5

5

CC

-

V

Input Threshold High

2.4

-

V

-

V

Input Hysteresis

-

V

Input Resistance

3

7

kΩ

TRANSMITTER OUTPUTS

Output Voltage Swing

Output Resistance

All Transmitter Outputs Loaded with 3kΩ to Ground

Full

±5.0

±5.4

10M

±35

-

V

Ω

V

= V+ = V- = 0V, Transmitter Output = ±2V

300

-

CC

Output Short-Circuit Current

Output Leakage Current

-

±60

±25

mA

µA

V

= ±12V, V

= 0V or 3V to 5.5V,

CC

OUT

Automatic Powerdown or FORCEOFF = GND

TIMING CHARACTERISTICS

Maximum Data Rate

R

= 3kΩ, C = 1000pF, One Transmitter Switching

Full

25

250

500

0.15

200

100

50

-

kBps

µs

L

Receiver Propagation Delay

Receiver Input to Receiver

Output, C = 150pF

L

t

-

PHL

PLH

-

µs

Receiver Output Enable Time

Receiver Output Disable Time

Transmitter Skew

Normal Operation

-

ns

-

ns

t

- t

PHL PLH

(Note 2)

-

ns

Receiver Skew

- t

PHL PLH

-

ns

Transition Region Slew Rate

V

= 3.3V, R = 3kΩ to 7kΩ,

C = 150pF to 2500pF

4

6

-

30

V/µs

CC

L

Measured From 3V to -3V

or -3V to 3V

C = 150pF to 1000pF

-

L

ESD PERFORMANCE

RS-232 Pins (T

, R

)

Human Body Model

25

-

±15

±8

-

kV

OUT IN

IEC61000-4-2 Contact Discharge

IEC61000-4-2 Air Gap Discharge

Human Body Model

±15

±2

All Other Pins

NOTE:

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

Charge-Pump

Detailed Description

Intersil’s new ISL422XE devices utilize regulated on-chip

dual charge pumps as voltage doublers, and voltage

inverters to generate ±5.5V transmitter supplies from a V

supply as low as 3.0V. This allows them 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

voltage doubler and inverter functions. The charge pumps

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

The ISL422XE operate from a single +2.7V 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

CC

specifications even with V

= 3.0V. The circuit is divided

CC

into three sections: The charge pump, the transmitters, and

the receivers.

5

ISL4221E, ISL4223E

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

resulting in significant power savings.

11mA current required by comparable 5V RS-232 devices,

allowing users to reduce system power simply by switching

to this new family.

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.

Powerdown Functionality

The already low current requirement drops significantly

when the device enters powerdown mode. In powerdown,

supply current drops to 150nA, because the on-chip charge

pump turns off (V+ collapses to V , V- collapses to GND),

CC

and the transmitter outputs three-state. Receiver outputs are

unaffected by powerdown; refer to Table 2 for details. This

micro-power mode makes the ISL422XE ideal for battery

powered and portable applications.

All transmitter outputs disable and assume a high

impedance state when the device enters the powerdown

mode (see Table 2). These outputs may be driven to ±12V

when disabled.

The devices guarantee a 250kBps data rate for full load

V

CC

V

CC

conditions (3kΩ and 1000pF), V

≥ 3.0V, with one

CC

transmitter operating at full speed. Under more typical

conditions of V ≥ 3.3V, R = 3kΩ, and C = 250pF, one

CURRENT

FLOW

V

CC

L

transmitter easily operates at 900kBps.

V

= V

CC

OUT

Transmitter inputs float if left unconnected, and may cause

increases. Connect unused inputs to GND for the best

performance.

Rx

I

CC

POWERED

DOWN

UART

Receivers

Tx

OLD

RS-232 CHIP

All the ISL422XE devices contain standard inverting

receivers that three-state via the EN control line. 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

GND

SHDN = GND

FIGURE 2. POWER DRAIN THROUGH POWERED DOWN

PERIPHERAL

off (V

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

CC

uses hysteresis to increase noise immunity and decrease

errors due to slow input signal transitions.

V

CC

V

CC

TRANSITION

DETECTOR

R

XIN

XOUT

GND ≤ V

TO

ISL422XE

≤ V

-25V ≤ V

≤ +25V

5kΩ

ROUT

CC

RIN

WAKE-UP

LOGIC

GND

V

FIGURE 1. INVERTING RECEIVER CONNECTIONS

CC

INVALID

Receivers driving a powered down UART must be disabled

to prevent current flow through, and possible damage to, the

UART’s protection diodes (see Figures 2 and 3). This can be

accomplished on the ISL422XE by driving the EN input high

whenever the UART powers down. Figure 3 also shows that

the INVALID output can be used to determine when the

UART should be powered down. When the RS-232 cable is

disconnected, INVALID switches low indicating that the

UART is no longer needed. Reconnecting the cable drives

INVALID back high, indicating that the UART should be

powered up.

R

T

V

= HI-Z

X

OUT

R

OUT

POWERED

DOWN

UART

R

IN

T

X

IN

T

OUT

EN = V

CC

FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN

Software Controlled (Manual) Powerdown

The ISL422XE family provides pins that allow the user to

force the IC into the low power, standby state.

Low Power Operation

These 3V devices require a nominal supply current of

The ISL422XE utilize a two pin approach where the

FORCEON and FORCEOFF inputs determine the IC’s

0.3mA, even at V

powerdown mode). This is considerably less than the 5mA to

= 5.5V, during normal operation (not in

CC

6

ISL4221E, ISL4223E

TABLE 2. POWERDOWN AND ENABLE LOGIC TRUTH TABLE

RS-232 SIGNAL

PRESENT AT

FORCEOFF FORCEON

EN

TRANSMITTER RECEIVER INVALID

RECEIVER INPUT?

INPUT

OUTPUTS

OUTPUTS OUTPUT

MODE OF OPERATION

Normal Operation

NO

H

L

H

L

H

L

Active

High-Z

Active

High-Z

Active

High-Z

Active

High-Z

Active

High-Z

L

(Auto Powerdown Disabled)

Active

YES

NO

Active

H

L

Normal Operation

(Auto Powerdown Enabled)

L

H

L

Active

L

High-Z

Powerdown Due to Auto Powerdown

Logic

NO

L

H

L

YES

NO

X

H

L

Manual Powerdown

L

H

L

Manual Powerdown w/Rcvr. Disabled

Manual Powerdown

L

NO

L

H

L

Manual Powerdown w/Rcvr. Disabled

mode. For always enabled operation, FORCEON and

FORCEOFF are both strapped high. To switch between

active and powerdown modes, under logic or software

control, only the FORCEOFF input need be driven. The

FORCEON state isn’t critical, as FORCEOFF dominates

MASTER POWERDOWN LINE

POWER

MANAGEMENT

UNIT

0.1µF

1MΩ

over FORCEON. Nevertheless, if strictly manual control over

powerdown is desired, the user must strap FORCEON high

to disable the automatic powerdown circuitry.

FORCEOFF

FORCEON

ISL422XE

Connecting FORCEOFF and FORCEON together disables

the automatic powerdown feature, enabling them to function

as a manual SHUTDOWN input (see Figure 4).

FIGURE 5. CIRCUIT TO PREVENT AUTO POWERDOWN FOR

100ms AFTER FORCED POWERUP

FORCEOFF

PWR

Automatic Powerdown

FORCEON

MGT

Even greater power savings is available by using the

automatic powerdown function. When no valid RS-232

voltages (see Figure 6) are sensed on any receiver input for

30µs, the charge pump and transmitters powerdown, thereby

reducing supply current to 10nA. Invalid receiver levels occur

whenever the driving peripheral’s outputs are shut off

(powered down) or when the RS-232 interface cable is

disconnected. The ISL422XE powers back up whenever it

detects a valid RS-232 voltage level on any receiver input.

This automatic powerdown feature provides additional

system power savings without changes to the existing

operating system.

LOGIC

INVALID

ISL422XE

I/O

UART

CPU

Automatic powerdown operates when the FORCEON input

is low, and the FORCEOFF input is high. Tying FORCEON

high disables automatic powerdown, but manual powerdown

is always available via the overriding FORCEOFF input.

Table 2 summarizes the automatic powerdown functionality.

FIGURE 4. CONNECTIONS FOR MANUAL POWERDOWN

WHEN NO VALID RECEIVER SIGNALS ARE

PRESENT

The time to recover from automatic powerdown mode is

Some applications may need more time to wake up from

shutdown. If automatic powerdown is being utilized, the RS-

232 device will reenter powerdown if valid receiver levels

aren’t reestablished within 30µs of the ISL422XE powering

up. Figure 5 illustrates a circuit that keeps the ISL422XE

typically 100µs.

7

ISL4221E, ISL4223E

from initiating automatic powerdown for 100ms after

powering up. This gives the slow-to-wake peripheral circuit

time to reestablish valid RS-232 output levels.

circuitry. When automatic powerdown is utilized, INVALID =

0 indicates that the ISL422XE is in powerdown mode.

RECEIVER

INPUTS

INVALID

REGION

}

The time to recover from automatic powerdown mode is

typically 100µs.

TRANSMITTER

OUTPUTS

INVALID Output

The INVALID output always indicates whether or not a valid

RS-232 signal (see Figure 6) is present at any of the receiver

inputs (see Table 2), giving the user an easy way to

determine when the interface block should power down.

Invalid receiver levels occur whenever the driving

V

CC

INVALID

t

INVH

INVL

OUTPUT

0

PWR UP

AUTOPWDN

V+

peripheral’s outputs are shut off (powered down) or when the

RS-232 interface cable is disconnected. In the case of a

disconnected interface cable where all the receiver inputs

are floating (but pulled to GND by the internal receiver pull

down resistors), the INVALID logic detects the invalid levels

and drives the output low. The power management logic

then uses this indicator to power down the interface block.

Reconnecting the cable restores valid levels at the receiver

inputs, INVALID switches high, and the power management

logic wakes up the interface block. INVALID can also be

used to indicate the DTR or RING INDICATOR signal, as

long as the other receiver inputs are floating, or driven to

GND (as in the case of a powered down driver).

V

CC

0

V-

FIGURE 7. AUTOMATIC POWERDOWN AND INVALID TIMING

DIAGRAMS

Capacitor Selection

The charge pumps require 0.1µF, or greater, capacitors for

proper operation. Increasing the capacitor values (by a factor

of 2) reduces ripple on the transmitter outputs and slightly

reduces power consumption.

VALID RS-232 LEVEL - ISL422XE IS ACTIVE

2.7V

When using minimum required capacitor values, make sure

that capacitor values do not degrade excessively with

temperature. If in doubt, use capacitors with a larger nominal

value. The capacitor’s equivalent series resistance (ESR)

usually rises at low temperatures and it influences the

amount of ripple on V+ and V-.

INDETERMINATE - POWERDOWN MAY OR

MAY NOT OCCUR

0.3V

INVALID LEVEL - POWERDOWN OCCURS AFTER 30µs

-0.3V

INDETERMINATE - POWERDOWN MAY OR

MAY NOT OCCUR

Power Supply Decoupling

In most circumstances a 0.1µF bypass capacitor is

adequate. In applications that are particularly sensitive to

-2.7V

VALID RS-232 LEVEL - ISL422XE IS ACTIVE

power supply noise, decouple V

to ground with a

CC

capacitor of the same value as the charge-pump capacitor C .

1

FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS

Connect the bypass capacitor as close as possible to the IC.

INVALID switches low after invalid levels have persisted on

all of the receiver inputs for more than 30µs (see Figure 7).

INVALID switches back high 1µs after detecting a valid

RS-232 level on a receiver input. INVALID operates in all

modes (forced or automatic powerdown, or forced on), so it

is also useful for systems employing manual powerdown

Transmitter Outputs when Exiting

Powerdown

Figure 8 shows the response of two transmitter outputs

when exiting powerdown mode. As they activate, the two

transmitter outputs properly go to opposite RS-232 levels,

with no glitching, ringing, nor undesirable transients. Each

transmitter is loaded with 3kΩ in parallel with 2500pF.

8

ISL4221E, ISL4223E

Note that the transmitters enable only when the magnitude

of the supplies exceed approximately 3V.

5V/DIV.

T1

IN

5V/DIV.

FORCEOFF

T1

OUT

2V/DIV.

R1

OUT

V

= +3.3V

CC

C1 - C4 = 0.1µF

T2

V

= +3.3V

CC

C1 - C4 = 0.1µF

5µs/DIV.

FIGURE 10. LOOPBACK TEST AT 120kBps

TIME (20µs/DIV.)

FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING

POWERDOWN

5V/DIV.

T1

IN

Operation Down to 2.7V

ISL422XE transmitter outputs meet RS-562 levels (±3.7V), at

the full data rate, with V

as low as 2.7V. RS-562 levels

CC

typically ensure inter operability with RS-232 devices.

T1

OUT

High Data Rates

The ISL422XE maintain the RS-232 ±5V minimum

transmitter output voltages even at high data rates. Figure 9

details a transmitter loopback test circuit, and Figure 10

illustrates the loopback test result at 120kBps. For this test,

all transmitters were simultaneously driving RS-232 loads in

parallel with 1000pF, at 120kBps. Figure 11 shows the

loopback results for a single transmitter driving 1000pF and

an RS-232 load at 250kBps. The static transmitters were

also loaded with an RS-232 receiver.

R1

V

= +3.3V

CC

C1 - C4 = 0.1µF

2µs/DIV.

FIGURE 11. LOOPBACK TEST AT 250kBps

Interconnection with 3V and 5V Logic

The ISL422XE directly interface with 5V CMOS and TTL

logic families. Nevertheless, with the ISL422XE at 3.3V, and

the logic supply at 5V, AC, HC, and CD4000 outputs can

drive ISL422XE inputs, but ISL422XE outputs do not reach

V

CC

+

0.1µF

V

CC

V+

V-

+

C1+

C1-

C2+

C2-

the minimum V for these logic families. See Table 3 for

IH

+

C

1

2

C

3

4

more information.

ISL422XE

TABLE 3. LOGIC FAMILY COMPATIBILITY WITH VARIOUS

SUPPLY VOLTAGES

+

C

+

C

SYSTEM

V

CC

POWER-SUPPLY SUPPLY

T

IN

OUT

VOLTAGE

(V)

VOLTAGE

(V)

COMPATIBILITY

1000pF

R

IN

R

OUT

3.3

Compatible with all CMOS

families.

FORCEON

FORCEOFF

5k

5

Compatible with all TTL and

CMOS logic families.

V

CC

5

3.3

Compatible with ACT and HCT

CMOS, and with TTL. ISL422XE

outputs are incompatible with AC,

HC, and CD4000 CMOS inputs.

FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT

9

ISL4221E, ISL4223E

IEC61000-4-2 Testing

±15kV ESD Protection

The IEC61000 test method applies to finished equipment,

rather than to an individual IC. Therefore, the pins most likely

to suffer an ESD event are those that are exposed to the

outside world (the RS-232 pins in this case), and the IC is

tested in its typical application configuration (power applied)

rather than testing each pin-to-pin combination. The lower

current limiting resistor coupled with the larger charge

storage capacitor yields a test that is much more severe than

the HBM test. The extra ESD protection built into this

device’s RS-232 pins allows the design of equipment

meeting level 4 criteria without the need for additional board

level protection on the RS-232 port.

All pins on ISL422XE devices include ESD protection

structures, but the RS-232 pins (transmitter outputs and

receiver inputs) incorporate advanced structures which allow

them to survive ESD events up to ±15kV. The RS-232 pins

are particularly vulnerable to ESD damage because they

typically connect to an exposed port on the exterior of the

finished product. Simply touching the port pins, or

connecting a cable, can cause an ESD event that might

destroy unprotected ICs. These new ESD structures protect

the device whether or not it is powered up, protect without

allowing any latchup mechanism to activate, and don’t

interfere with RS-232 signals as large as ±25V.

AIR-GAP DISCHARGE TEST METHOD

Human Body Model (HBM) Testing

For this test method, a charged probe tip moves toward the

IC pin until the voltage arcs to it. The current waveform

delivered to the IC pin depends on approach speed,

humidity, temperature, etc., so it is difficult to obtain

repeatable results. The “E” device RS-232 pins withstand

±15kV air-gap discharges.

As the name implies, this test method emulates the ESD

event delivered to an IC during human handling. The tester

delivers the charge through a 1.5kΩ current limiting resistor,

making the test less severe than the IEC61000 test which

utilizes a 330Ω limiting resistor. The HBM method

determines an ICs ability to withstand the ESD transients

typically present during handling and manufacturing. Due to

the random nature of these events, each pin is tested with

respect to all other pins. The RS-232 pins on “E” family

devices can withstand HBM ESD events to ±15kV.

CONTACT DISCHARGE TEST METHOD

During the contact discharge test, the probe contacts the

tested pin before the probe tip is energized, thereby

eliminating the variables associated with the air-gap

discharge. The result is a more repeatable and predictable

test, but equipment limits prevent testing devices at voltages

higher than ±8kV. All “E” family devices survive ±8kV contact

discharges on the RS-232 pins.

10

ISL4221E, ISL4223E

o

Typical Performance Curves V = 3.3V, T = 25 C

CC

A

6

25

20

V

+

OUT

4

2

1 TRANSMITTER AT 250kBps

OTHER TRANSMITTERS AT 30kBps

0

15

10

5

-SLEW

-2

-4

+SLEW

V

-

OUT

-6

0

1000

2000

3000

4000

5000

0

1000

2000

3000

4000

5000

LOAD CAPACITANCE (pF)

FIGURE 12. TRANSMITTER OUTPUT VOLTAGE vs LOAD

CAPACITANCE

FIGURE 13. SLEW RATE vs LOAD CAPACITANCE

45

ISL4221E

40

ISL4223E

40

35

30

25

20

15

10

250kBps

35

250kBps

30

25

120kBps

20kBps

20

15

10

5

120kBps

20kBps

5

0

1000

2000

3000

4000

5000

0

1000

2000

3000

4000

5000

LOAD CAPACITANCE (pF)

FIGURE 14. SUPPLY CURRENT vs LOAD CAPACITANCE

WHEN TRANSMITTING DATA

FIGURE 15. SUPPLY CURRENT vs LOAD CAPACITANCE

WHEN TRANSMITTING DATA

Die Characteristics

3.5

NO LOAD

ALL OUTPUTS STATIC

SUBSTRATE POTENTIAL (POWERED UP):

3.0

2.5

2.0

1.5

1.0

0.5

0

GND

TRANSISTOR COUNT:

ISL4221E: 286

ISL4223E: 357

PROCESS:

Si Gate CMOS

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

SUPPLY VOLTAGE (V)

FIGURE 16. SUPPLY CURRENT vs SUPPLY VOLTAGE

11

ISL4221E, ISL4223E

Quad Flat No-Lead Plastic Package (QFN)

Micro Lead Frame Plastic Package (MLFP)

L16.5x5

16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE

(COMPLIANT TO JEDEC MO-220VHHB ISSUE C)

MILLIMETERS

SYMBOL

MIN

NOMINAL

MAX

1.00

0.05

1.00

NOTES

A

A1

A2

A3

b

0.80

0.90

-

9

0.20 REF

9

0.28

2.55

0.33

0.40

2.85

5, 8

D

5.00 BSC

-

D1

D2

E

4.75 BSC

9

2.70

7, 8

5.00 BSC

-

E1

E2

e

4.75 BSC

9

2.70

7, 8

0.80 BSC

-

k

0.25

0.35

-

L

0.60

0.75

0.15

8

L1

N

-

16

4

-

10

2

Nd

Ne

P

3

4

-

3

0.60

12

9

θ

-

9

Rev. 2 10/02

NOTES:

1. Dimensioning and tolerancing conform to ASME Y14.5-1994.

2. N is the number of terminals.

3. Nd and Ne refer to the number of terminals on each D and E.

4. All dimensions are in millimeters. Angles are in degrees.

5. Dimension b applies to the metallized terminal and is measured

between 0.15mm and 0.30mm from the terminal tip.

6. The configuration of the pin #1 identifier is optional, but must be

located within the zone indicated. The pin #1 identifier may be

either a mold or mark feature.

7. Dimensions D2 and E2 are for the exposed pads which provide

improved electrical and thermal performance.

8. Nominal dimensionsare provided toassistwith PCBLandPattern

Design efforts, see Intersil Technical Brief TB389.

9. Features and dimensions A2, A3, D1, E1, P & θ are present when

Anvil singulation method is used and not present for saw

singulation.

10. Depending on the method of lead termination at the edge of the

package, a maximum 0.15mm pull back (L1) maybe present. L

minus L1 to be equal to or greater than 0.3mm.

12

ISL4221E, ISL4223E

Quad Flat No-Lead Plastic Package (QFN)

Micro Lead Frame Plastic Package (MLFP)

L20.5x5

20 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE

(COMPLIANT TO JEDEC MO-220VHHC ISSUE C)

MILLIMETERS

SYMBOL

MIN

NOMINAL

MAX

1.00

0.05

1.00

NOTES

A

A1

A2

A3

b

0.80

0.90

-

9

0.20 REF

9

0.23

2.95

0.28

0.38

3.25

5, 8

D

5.00 BSC

-

D1

D2

E

4.75 BSC

9

3.10

7, 8

5.00 BSC

-

E1

E2

e

4.75 BSC

9

3.10

7, 8

0.65 BSC

-

k

0.25

0.35

-

L

0.60

0.75

0.15

8

L1

N

-

20

5

-

10

2

Nd

Ne

P

3

-

0.60

12

9

θ

-

9

Rev. 3 10/02

NOTES:

1. Dimensioning and tolerancing conform to ASME Y14.5-1994.

2. N is the number of terminals.

3. Nd and Ne refer to the number of terminals on each D and E.

4. All dimensions are in millimeters. Angles are in degrees.

5. Dimension b applies to the metallized terminal and is measured

between 0.15mm and 0.30mm from the terminal tip.

6. The configuration of the pin #1 identifier is optional, but must be

located within the zone indicated. The pin #1 identifier may be

either a mold or mark feature.

7. Dimensions D2 and E2 are for the exposed pads which provide

improved electrical and thermal performance.

8. Nominal dimensionsare provided toassistwith PCBLandPattern

Design efforts, see Intersil Technical Brief TB389.

9. Features and dimensions A2, A3, D1, E1, P & θ are present when

Anvil singulation method is used and not present for saw

singulation.

10. Depending on the method of lead termination at the edge of the

package, a maximum 0.15mm pull back (L1) maybe present. L

minus L1 to be equal to or greater than 0.3mm.

All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.

Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality

Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without

notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and

reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result

from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.

For information regarding Intersil Corporation and its products, see www.intersil.com

13


型号：	ISL4221
厂家：	Intersil
描述：	QFN Packaged, +/-15kV ESD Protected, +2.7V to +5.5V, 150Nanoamp, 250kBps, RS-232 Transmitters/Receivers QFN封装， +/- 15kV ESD保护， + 2.7V至+ 5.5V ， 150Nanoamp ， 250kbps的， RS - 232发射器/接收器
文件：	总13页 (文件大小：391K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

ISL4221 [INTERSIL]

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