DATASHEET
ISL4238E, ISL4244E, ISL4245E
QFN Packaged, ±15kV ESD Protected, +2.7V to +5.5V, 10Nanoamp, 250kbps/
1Mbps, RS-232 Transceivers with Enhanced Automatic Power-down
The Intersil ISL4238E, ISL4244E and ISL4245E devices are
2.7V to 5.5V powered RS-232 transmitters/receivers which
meet ElA/TIA-232 and V.28/V.24 specifications, even at
VCC = 3.0V. Additionally, 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 notebook
and laptop computers where the low operational, and even
lower standby power consumption is critical. Efficient on-chip
charge pumps, coupled with manual and enhanced
automatic power-down functions, reduce the standby supply
current to a 10nA trickle. Tiny 5mmx5mm 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 (ISL4238E/ISL4244E)/1Mbps (ISL4245E) are
guaranteed at worst case load conditions.
The ISL424xE are 3 driver, 5 receiver (DTE) devices that,
coupled with the QFN package, provide the industry’s
smallest, lowest power complete serial port suitable for
PDAs, and laptop or notebook computers. The 32 Ld 5x5
QFN requires 60% less board area than a 28 lead TSSOP,
and is nearly 20% thinner. The devices also include a
noninverting always-active receiver for “wake-up” capability.
The ISL4238E is a 5 driver, 3 receiver device optimized for
DCE applications with full hardware handshaking. It also
includes a noninverting always-active receiver for RING
INDICATOR monitoring. Transmitter and logic inputs include
active feedback resistors that retain the input state once
driven to a valid logic level.
These devices feature an enhanced automatic power-down
function which powers down the on-chip power-supply and
driver circuits. This occurs when all receiver and transmitter
inputs detect no signal transitions for a period of 30s. These
devices power back-up, automatically, whenever they sense
a transition on any transmitter or receiver input.
Table 1 summarizes the features of the ISL4238E,
ISL4244E, ISL4245, while Application Note AN9863
summarizes the features of each device comprising the 3V
RS-232 family.
FN8038
Rev 5.00
May 13, 2010
Features
• Parameters Fully Specified for 10% Tolerance Supplies
and Full Industrial Temp Range
• Available in Small QFN (5mm x 5mm) Package which is
60% Smaller than a 28 Lead TSSOP
• ESD Protection for RS-232 I/O Pins to ±15kV (IEC61000)
• DTE (ISL4244E/45E) and DCE (ISL4238E) Versions
• Lowest Supply Current in Power-down . . . . . . . . . . .10nA
• Active Feedback Resistors on TX and Logic Inputs
(ISL4238E)
• Flow Through Pinouts
• Manual and Enhanced Automatic Power-down Features
• Guaranteed Minimum Data Rate
250kbps (ISL4238E/ISL4244E) / 1Mbps (ISL4245E)
• Latch-Up Free
• On-Chip Charge Pumps Require Only Four External
0.1µF Capacitors
• Wide Power Supply Range . . . . . . Single +2.7V to +5.5V
• Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V
• RS-232 Compatible with VCC = 2.7V
• Pb-Free Available (RoHS Compliant)
Applications
• Any Space Constrained System Requiring RS-232 Ports
- Battery Powered, Hand-Held, and Portable Equipment
- Laptop Computers, Notebooks
- PDAs and Palmtops, Data Cables
- Cellular/Mobile Phones, Digital Cameras, GPS
Receivers
Related Literature
• Technical Brief TB363 “Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices”
• Technical Brief TB379 “Thermal Characterization of
Packages for ICs”
• Technical Brief TB389 “PCB Land Pattern Design and
Surface Mount Guidelines for QFN Packages”
FN8038 Rev 5.00
May 13, 2010
Page 1 of 17
ISL4238E, ISL4244E, ISL4245E
TABLE 1. SUMMARY OF FEATURES
NO. OF NO. OF
PART NUMBER
Tx.
Rx.
CONFIG.
QFN PKG.
NO. OF
MONITOR Rx.
(ROUTB)
DATA
RATE
(kbps)
Rx. ENABLE
FUNCTION?
MANUAL
POWERDOWN?
ENHANCED
AUTOMATIC
POWERDOWN
FUNCTION?
250
No
Yes
Yes
ISL4238E
5
3
DCE
5x5
1
ISL4244E
3
5
DTE
5x5
1
250
No
Yes
Yes
ISL4245E
3
5
DTE
5x5
1
1000
No
Yes
Yes
Ordering Information
PART NUMBER
PART MARKING
TEMP.
RANGE (°C)
PACKAGE
PKG.
DWG. #
ISL4238EIR
ISL 4238EIR
-40 to +85
32 Ld 5X5 QFN
L32.5x5B
ISL4238EIRZ
(Note)
ISL4238 EIRZ
-40 to +85
32 Ld 5X5 QFN
(Pb-Free)
L32.5x5B
ISL4238EIR-T*
ISL 4238EIR
-40 to +85
32 Ld 5X5 QFN
Tape & Reel
L32.5x5B
ISL4238EIRZ-T*
(Note)
ISL4238 EIRZ
-40 to +85
32 Ld 5X5 QFN
Tape & Reel, (Pb-Free)
L32.5x5B
ISL4244EIR
ISL 4244EIR
-40 to +85
32 Ld 5X5 QFN
L32.5x5B
ISL4244EIRZ
(Note)
ISL4244 EIRZ
-40 to +85
32 Ld 5X5 QFN
(Pb-free)
L32.5x5B
ISL4244EIR-T*
ISL 4244EIR
-40 to +85
32 Ld 5X5 QFN
Tape & Reel
L32.5x5B
ISL4244EIRZ-T*
(Note)
ISL4244 EIRZ
-40 to +85
32 Ld 5X5 QFN
Tape & Reel, (Pb-Free)
L32.5x5B
ISL4245EIR
ISL 4245EIR
-40 to +85
32 Ld 5X5 QFN
L32.5x5B
ISL4245EIRZ
(Note)
ISL4245 EIRZ
-40 to +85
32 Ld 5X5 QFN
(Pb-Free)
L32.5x5B
ISL4245EIR-T*
ISL 4245EIR
-40 to +85
32 Ld 5X5 QFN
Tape & Reel
L32.5x5B
ISL4245EIRZ-T*
(Note)
ISL4245 EIRZ
-40 to +85
32 Ld 5X5 QFN
Tape & Reel, (Pb-Free)
L32.5x5B
*Please refer to TB347 for details on reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100%
matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and 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-020.
FN8038 Rev 5.00
May 13, 2010
Page 2 of 17
ISL4238E, ISL4244E, ISL4245E
Pinouts
C2+
C1+
V+
VCC
NC
25
C2-
26
V-
27
NC
28
V+
C1+
29
NC
30
VCC
31
C2+
GND
C2-
V32
T1OUT
ISL4244E, ISL4245E
(32 LD QFN)
TOP VIEW
ISL4238E
(32 LD QFN)
TOP VIEW
32
31
30
29
28
27
26
25
1
24 C1-
R1IN
1
24 GND
T2OUT
2
23 T1IN
R2IN
2
23
T3OUT
3
22 T2IN
R3IN
3
22 FORCEON
R1IN
4
21 T3IN
R4IN
4
PD
C1-
21 FORCEOFF
PD
20 INVALID
8
17 R3OUT
T3OUT
8
17 R2OUT
10
11
12
13
14
15
16
9
10
11
12
13
14
15
16
NC
9
R3OUT
T5OUT
R4OUT
18 R1OUT
R5OUT
7
T1IN
T2OUT
T2IN
18 T4IN
T3IN
7
NC
R3IN
NC
19 R2OUTB
T5IN
6
R1OUTB
T1OUT
NC
19 R2OUT
INVALID
6
T4OUT
FORCEOFF
5
FORCEON
R5IN
5
NC
20 R1OUT
R2IN
Pin Descriptions
PIN
VCC
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.
TIN
TTL/CMOS compatible transmitter Inputs. (Note)
TOUT
RIN
ROUT
±15kV ESD Protected, RS-232 level (nominally ±5.5V) transmitter outputs.
±15kV ESD Protected, RS-232 compatible receiver inputs.
TTL/CMOS level receiver outputs.
ROUTB
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
that logic level until VCC is removed. Unused transmitter inputs may be left unconnected by the user.
FN8038 Rev 5.00
May 13, 2010
Page 3 of 17
ISL4238E, ISL4244E, ISL4245E
Typical Operating Circuits
ISL4238E
+3.3V
+
C1
0.1µF
(NOTE)
C2
0.1µF
T1IN
T2IN
T3IN
T4IN
T5IN
TTL/CMOS
LOGIC
LEVELS
0.1µF
28
+
C1+
26
27
VCC
V+
24
C129
C2+
+
31
C2-
V-
32
23
T1
22
T2
2
21
T3
3
18
T4
6
15
T5
8
+
C3
0.1µF
(NOTE)
C4
0.1µF
+
1
T1OUT
T2OUT
T3OUT
RS-232
LEVELS
T4OUT
T5OUT
14
R1OUTB
20
R1OUT
R2OUT
4
R1IN
R1
5k
19
5
R2
17
R3IN
R3
10
TO POWER
CONTROL
LOGIC
RS-232
LEVELS
7
R3OUT
VCC
R2IN
5k
11
12
5k
FORCEON
FORCEOFF
INVALID
GND
30
NOTE: For VCC = 3.15V (3.3V -5%), use C1 to C4 = 0.1µF or greater. For VCC = 3.0V (3.3V -10%), use C1 to C4 = 0.22µF or greater.
FN8038 Rev 5.00
May 13, 2010
Page 4 of 17
ISL4238E, ISL4244E, ISL4245E
Typical Operating Circuits (Continued)
ISL4244E, ISL4245E
+3.3V
+
C1
0.1µF
C2
0.1µF
T1IN
T2IN
T3IN
0.1µF
28
+
C1+
26
VCC
23
C129
C2+
+
30
C2-
27
V+
V-
12
T1
11
T2
10
T3
31
6
7
8
+
C3
0.1µF
C4
0.1µF
+
T1OUT
T2OUT
RS-232
LEVELS
T3OUT
19
R2OUTB
TTL/CMOS
LOGIC LEVELS
18
1
R1OUT
R2OUT
R1IN
R1
5k
17
2
R2
15
3
R3OUT
R3IN
R3
R4OUT
5k
14
4
R4
R5OUT
TO POWER
CONTROL LOGIC
21
20
RS-232
LEVELS
R4IN
5k
13
22
VCC
R2IN
5k
5
5k
R5
FORCEON
R5IN
FORCEOFF
INVALID
GND
24
FN8038 Rev 5.00
May 13, 2010
Page 5 of 17
ISL4238E, ISL4244E, ISL4245E
Absolute Maximum Ratings
Thermal Information
VCC to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V
V- to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V
V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V
Input Voltages
TIN, FORCEOFF, FORCEON. . . . . . . . . . . . . . . . . . . -0.3V to 6V
RIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±25V
Output Voltages
TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±13.2V
ROUT, INVALID. . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VCC +0.3V
Short Circuit Duration
TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
ESD Rating . . . . . . . . . . . . See “ESD PERFORMANCE” on page 8
Thermal Resistance (Typical, Notes 1, 2) JA (°C /W) JC (°C /W)
32 Ld QFN Package. . . . . . . . . . . . . . .
32
3.0
Moisture Sensitivity (see Technical Brief TB363)
QFN Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1
Maximum Storage Temperature Range . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile. . . . . . . . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Operating Conditions
Temperature Range
ISL42xxEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +85°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and
result in failures not covered by warranty.
NOTE:
1. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See
Tech Brief TB379, and Tech Brief TB389.
2. For JC, the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
Test Conditions: ISL4238E VCC = 3.15V to 5.5V, C1 to C4 = 0.1µF; VCC = 3V, C1 to C4 = 0.22µF;
ISL424xE VCC = 3V to 5.5V, C1 to C4 = 0.1µF; Unless Otherwise Specified. Typicals are at TA = +25°C
PARAMETER
TEST CONDITIONS
TEMP
(°C)
MIN
(Note 7)
TYP
MAX
(Note 7) UNITS
Full
2.7
-
5.5
V
25
-
3
300
nA
50
300
nA
DC CHARACTERISTICS
Operating Voltage Range
Supply Current, Automatic Power- All RIN Open, FORCEON = GND, FORCEOFF = VCC
down
Supply Current, Power-down
All RIN Open, FORCEOFF = GND
Full
25
-
Full
Supply Current,
Automatic Power-down Disabled
All Outputs Unloaded, FORCEON = FORCEOFF = VCC,
VCC = 3.0V
25
-
Full
3
300
nA
50
300
nA
0.3
1.0
mA
0.3
1.5
mA
-
0.8
V
LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
TIN, FORCEON, FORCEOFF
Full
-
Input Logic Threshold High
TIN, FORCEON, FORCEOFF, VCC = 3.6V
Full
2.0
-
-
V
25
-
0.5
-
V
Transmitter Input Hysteresis
Input Leakage Current
TIN, FORCEON, FORCEOFF (ISL4238E, Note 3)
Full
-
±0.01
±1.0
µA
Output Leakage Current
FORCEOFF = GND
Full
-
±0.05
±10
µA
Output Voltage Low
IOUT = 1.6mA
Full
-
-
0.4
V
Output Voltage High
IOUT = -1.0mA
Full
-
V
V
VCC - 0.6 VCC - 0.1
RECEIVER INPUTS
Input Voltage Range
Full
-25
-
25
Input Threshold Low
VCC = 3.0V
Full
-
1.0
0.6
V
Input Threshold High
VCC = 3.6V
Full
2.4
1.5
-
V
Input Hysteresis
25
-
0.5
-
V
Input Resistance
Full
3
5
7
k
-
V
TRANSMITTER OUTPUTS
Output Voltage Swing
All Transmitter Outputs Loaded with 3k to Ground
Full
±5.0
±5.4
Output Resistance
VCC = V+ = V- = 0V, Transmitter Output = ±2V
Full
300
10M
-
Full
-
±35
±60
mA
Full
-
-
±25
µA
Output Short-Circuit Current
Output Leakage Current
FN8038 Rev 5.00
May 13, 2010
VOUT =±12V, VCC = 0V or 3V to 5.5V,
Automatic Power-down or FORCEOFF = GND
Page 6 of 17
ISL4238E, ISL4244E, ISL4245E
Electrical Specifications
Test Conditions: ISL4238E VCC = 3.15V to 5.5V, C1 to C4 = 0.1µF; VCC = 3V, C1 to C4 = 0.22µF;
ISL424xE VCC = 3V to 5.5V, C1 to C4 = 0.1µF; Unless Otherwise Specified. Typicals are at TA = +25°C
PARAMETER
TEST CONDITIONS
TEMP
(°C)
MIN
(Note 7)
TYP
MAX
(Note 7) UNITS
ENHANCED AUTOMATIC POWER-DOWN (FORCEON = GND, FORCEOFF = VCC)
Receiver Input Thresholds to
INVALID High
(see Figure 6)
Full
-2.7
-
2.7
V
Receiver Input Thresholds to
INVALID Low
(see Figure 6)
Full
-0.3
-
0.3
V
INVALID, Output Voltage Low
IOUT = 1.6mA
Full
-
-
0.4
V
INVALID, Output Voltage High
IOUT = -1.0mA
Full
VCC - 0.6
-
-
V
Receiver Positive or Negative
Threshold to INVALID High Delay
(tINVH)
25
-
0.5
1
µs
Full
-
0.9
1.5
µs
25
-
60
100
µs
100
150
µs
Receiver Positive or Negative
Threshold to INVALID Low Delay
(tINVL)
ISL4238E
Receiver Positive or Negative
Threshold to INVALID Low Delay
(tINVL)
ISL4244E/ISL42445E
Receiver or Transmitter Edge to
Transmitters Enabled Delay (tWU)
(Note 4)
Full
Receiver or Transmitter Edge to
Transmitters Disabled Delay
(tAUTOPWDN)
(Note 4)
Maximum Data Rate
ISL4238E/4244E
Maximum Data Rate
ISL4245E
Full
25
-
30
50
µs
40
60
µs
-
20
100
µs
Full
15
30
60
sec
RL = 3kCL = 1000pF, One Transmitter Switching
Full
250
500
-
kbps
RL = 3kOne Transmitter CL = 1000pF
Switching
VCC = 3V to 4.5V, CL = 250pF
Full
250
900
-
kbps
Full
1000
2000
-
kbps
Full
1000
1500
-
kbps
25
-
0.15
0.3
µs
Full
-
0.2
0.35
µs
25
-
0.3
0.5
µs
Full
-
0.35
0.55
µs
25
-
120
250
ns
Full
TIMING CHARACTERISTICS
VCC = 4.5V to 5.5V,
CL = 1000pF
Receiver Propagation Delay
Receiver Input to Receiver tPHL
Output,
CL = 150pF
tPLH
Receiver Skew
tPHL - tPLH, CL = 150pF
Transmitter Propagation Delay
ISL4238E/44E
Transmitter Input to
Transmitter Output,
CL = 1000pF, RL = 3k
tPHL
tPLH
Transmitter Skew ISL4238E/44E
tPHL - tPLH (see Note 6), RL = 3k, CL = 1000pF
Transmitter Propagation Delay
ISL4245E
Transmitter Input to
Transmitter Output,
CL = 1000pF, RL = 3k
tPHL
tPLH
Transmitter Skew ISL4245E
tPHL - tPLH (see Note 5), RL = 3k, CL = 1000pF
Receiver Output Enable Time
Normal Operation, RL = 1k to 0.5VCC, CL = 15pF
FN8038 Rev 5.00
May 13, 2010
Full
-
150
300
ns
25
-
0.75
1
µs
Full
-
0.85
1.1
µs
25
-
0.8
1
µs
Full
-
0.9
1.1
µs
25
-
50
200
ns
Full
-
100
250
ns
25
-
0.4
0.8
µs
Full
-
0.5
0.8
µs
25
-
0.35
0.7
µs
Full
-
0.4
0.7
µs
25
-
50
200
ns
Full
-
60
250
ns
25
-
200
350
ns
Full
-
200
400
ns
Page 7 of 17
ISL4238E, ISL4244E, ISL4245E
Electrical Specifications
PARAMETER
Test Conditions: ISL4238E VCC = 3.15V to 5.5V, C1 to C4 = 0.1µF; VCC = 3V, C1 to C4 = 0.22µF;
ISL424xE VCC = 3V to 5.5V, C1 to C4 = 0.1µF; Unless Otherwise Specified. Typicals are at TA = +25°C
TEST CONDITIONS
Receiver Output Disable Time
Normal Operation, RL = 1k to 0.5VCC, CL = 15pF
Transmitter Output Enable Time
ISL4238E/ISL4244E/ISL4245E
Normal Operation, RL = 3k, CL = 1000pF
Transmitter Output Disable Time
ISL4238E/ISL4244E/ISL4245E
Normal Operation, RL = 3k, CL = 1000pF
Transition Region Slew Rate
ISL4238E/ISL4244E
VCC = 3V to 3.6V,
RL = 3kto 7k
Measured From 3V to -3V
or -3V to 3V
Transition Region Slew Rate
ISL4245E
CL = 150pF to 1000pF
CL = 150pF to 2500pF
VCC = 3V to 3.6V, RL = 3kto 7kMeasured From 3V to
-3V or -3V to 3V, CL = 150pF to 1000pF
TEMP
(°C)
MIN
(Note 7)
TYP
MAX
(Note 7) UNITS
25
-
350
500
Full
-
400
600
ns
25
-
25
40
µs
ns
Full
-
35
50
µs
25
-
2.5
4
µs
Full
-
2.7
4
µs
25
6
11
30
V/µs
Full
6
10
30
V/µs
25
4
9
30
V/µs
Full
4
8
30
V/µs
25
24
40
150
V/µs
Full
24
35
150
V/µs
ESD PERFORMANCE
RS-232 Pins (TOUT, RIN)
All Other Pins
Human Body Model
25
-
±15
-
kV
IEC61000-4-2 Air Gap Discharge
25
-
±15
-
kV
IEC61000-4-2 Contact Discharge
25
-
±8
-
kV
Human Body Model
25
-
±3
-
kV
NOTES:
3. ISL4238E inputs utilize a positive feedback resistor. The input current is negligible when the input is at either supply rail.
4. An “edge” is defined as a transition through the transmitter or receiver input thresholds.
5. Skew is measured at the receiver input switching points (1.4V).
6. Skew is measured at the transmitter zero crossing points.
7. 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.
Detailed Description
Transmitters
These interface ICs operate from a single +2.7V to +5.5V
supply, guarantee a 250kbps (ISL4238E/ISL4244E)/1Mbps
(ISL4245E) 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: The charge pump, the
transmitters, and the receivers.
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.
Charge-Pump
Intersil’s new RS-232 family utilizes regulated on-chip dual
charge pumps as voltage doublers, and voltage inverters to
generate ±5.5V transmitter supplies from a VCC supply as
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 0.1µF capacitors for the
voltage doubler and inverter functions. 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.
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.
The ISL4238E/ISL4244E guarantee a 250kbps data rate for
full load conditions (3k and 1000pF), VCC 3.0V, with one
transmitter operating at full speed. Under more typical
conditions of VCC 3.3V, RL = 3k, and CL = 250pF, one
transmitter easily operates at 1Mbps.
The ISL4245E guarantees a 1Mbps data rate for full load
conditions (3k and 250pF), VCC 3.0V, with one
transmitter operating at full speed. Under more typical
conditions of VCC 3.3V, RL = 3k, and CL = 250pF, one
transmitter easily operates at 1.4Mbps.
Transmitter inputs on the ISL424XE float if left unconnected,
and may cause ICC increases. Connect unused inputs to
FN8038 Rev 5.00
May 13, 2010
Page 8 of 17
ISL4238E, ISL4244E, ISL4245E
TABLE 2. POWER-DOWN LOGIC TRUTH TABLE
RCVR OR
XMTR
EDGE
WITHIN 30
SEC?
FORCEOFF FORCEON TRANSMITTER RECEIVER
ROUTB
INPUT
INPUT
OUTPUTS
OUTPUTS OUTPUTS
RS-232
LEVEL
PRESENT
AT
RECEIVER
INPUT?
INVALID
OUTPUT
NO
H
H
Active
Active
Active
No
L
NO
H
H
Active
Active
Active
Yes
H
YES
H
L
Active
Active
Active
No
L
YES
H
L
Active
Active
Active
Yes
H
NO
H
L
High-Z
Active
Active
No
L
NO
H
L
High-Z
Active
Active
Yes
H
X
L
X
High-Z
High-Z
Active
No
L
X
L
X
High-Z
High-Z
Active
Yes
H
MODE OF OPERATION
Normal Operation (Enhanced
Auto Power-down Disabled)
Normal Operation (Enhanced
Auto Power-down Enabled)
Power-down Due to Enhanced
Auto Power-down Logic
Manual Power-down
INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWER-DOWN)
X
Note 8
Note 8
Active
Active
Active
Yes
H
Normal Operation
X
Note 8
Note 8
High-Z
High-Z
Active
No
L
Forced Auto Power-down
NOTE:
8. Input is connected to INVALID Output.
GND for the best performance. ISL4238E transmitter inputs
incorporate an active positive feedback resistor that
maintains the last input state in the absence of a forcing
signal, so unused transmitter inputs may be left
unconnected.
Receivers
renders them useless for wake up functions, but the
corresponding monitor receiver can be dedicated to this task
as shown in Figure 3.
VCC
VCC
CURRENT
FLOW
VCC
ISL4238E, ISL4244E, ISL4245 devices contain standard
inverting receivers which can tristate via the FORCEOFF
control line. Additionally, they include a noninverting
(monitor) receiver (denoted by the ROUTB label) that is
always active, regardless of the state of any control lines.
Both receiver types convert RS-232 signals to CMOS output
levels and accept inputs up to ±25V while presenting the
required 3k to 7k 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.
VCC
RXOUT
RXIN
-25V VRIN +25V
5k
GND VROUT VCC
GND
FIGURE 1. INVERTING RECEIVER CONNECTIONS
The ISL4238E, ISL4244E, ISL4245 inverting receivers
disable during forced (manual) power-down, but not during
automatic power-down (see Table 2). Conversely, the
monitor receiver remains active even during manual powerdown making it extremely useful for Ring Indicator
monitoring. Standard receivers driving powered down
peripherals must be disabled to prevent current flow through
the peripheral’s protection diodes (see Figures 2 and 3). This
FN8038 Rev 5.00
May 13, 2010
VOUT = VCC
Rx
POWERED
DOWN
UART
Tx
GND
SHDN = GND
OLD
RS-232 CHIP
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN
PERIPHERAL
Low Power Operation
These 3V devices require a nominal supply current of
0.3mA, even at VCC = 5.5V, during normal operation (not in
power-down mode). This is considerably less than the 5mA
to 11mA current required by comparable 5V RS-232 devices,
allowing users to reduce system power simply by switching
to this new family.
Page 9 of 17
ISL4238E, ISL4244E, ISL4245E
VCC
FORCEOFF
PWR
MGT
LOGIC
TRANSITION
DETECTOR
TO
WAKE-UP
LOGIC
FORCEON
INVALID
ISL4238E
ISL4244E
ISL4245
ISL4238E
ISL4244E
ISL4245
VCC
ROUTB
RX
POWERED
DOWN
UART
ROUT
TX
I/O
UART
VOUT = HI-Z
RIN
CPU
T1IN
T1OUT
FORCEOFF = GND
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
Power-down Functionality
The already low current requirement drops significantly
when the device enters power-down mode. In power-down,
supply current drops to 10nA, because the on-chip charge
pump turns off (V+ collapses to VCC, V- collapses to GND),
and the transmitter outputs tristate. Inverting receiver
outputs disable only in manual power-down; refer to Table 2
for details. This micro-power mode makes these devices
ideal for battery powered and portable applications.
Software Controlled (Manual) Power-down
These devices allow the user to force the IC into the low
power, standby state, and utilize a two pin approach where
the FORCEON and FORCEOFF inputs determine the IC’s
mode. For always enabled operation, FORCEON and
FORCEOFF are both strapped high. To switch between
active and power-down modes, under logic or software
control, only the FORCEOFF input need be driven. The
FORCEON state isn’t critical, as FORCEOFF dominates
over FORCEON. Nevertheless, if strictly manual control over
power-down is desired, the user must strap FORCEON high
to disable the enhanced automatic power-down circuitry.
ISL4238E, ISL4244E, ISL4245 inverting (standard) receiver
outputs also disable when the device is in manual powerdown, thereby eliminating the possible current path through
a shutdown peripheral’s input protection diode (see Figures
2 and 3).
Connecting FORCEOFF and FORCEON together disables
the enhanced automatic power-down feature, enabling them
to function as a manual SHUTDOWN input (see Figure 4).
With any of the previous mentioned control schemes, the
time required to exit power-down, and resume transmission
is only 100µs.
FN8038 Rev 5.00
May 13, 2010
FIGURE 4. CONNECTIONS FOR MANUAL POWER-DOWN
WHEN NO VALID RECEIVER SIGNALS ARE
PRESENT
When using both manual and enhanced automatic powerdown (FORCEON = 0), the ISL4238E, ISL4244E, ISL4245
won’t power up from manual power-down until both
FORCEOFF and FORCEON are driven high, or until a
transition occurs on a receiver or transmitter input. Figure 5
illustrates a circuit for ensuring that the ISL4238E,
ISL4244E, ISL4245 powers up as soon as FORCEOFF
switches high. The rising edge of the Master Power-down
signal forces the device to power up, and the ISL4238E,
ISL4244E, ISL4245 returns to enhanced automatic powerdown mode an RC time constant after this rising edge. The
time constant isn’t critical, because the ISL4238E,
ISL4244E, ISL4245 remains powered up for 30s after the
FORCEON falling edge, even if there are no signal
transitions. This gives slow-to-wake systems (e.g., a mouse)
plenty of time to start transmitting, and as long as it starts
transmitting within 30s both systems remain enabled.
POWER
MANAGEMENT
UNIT
MASTER POWER-DOWN LINE
0.1µF
FORCEOFF
1M
FORCEON
ISL4238E, ISL4244E, ISL4245
FIGURE 5. CIRCUIT TO ENSURE IMMEDIATE POWER UP
WHEN EXITING FORCED POWER-DOWN
INVALID Output
The INVALID output always indicates (see Table 2) whether or
not 30µs have elapsed with invalid RS-232 signals (see Figures
6 and 9) persisting on all of the receiver inputs, giving the user
an easy way to determine when the interface block should
power down. Invalid receiver levels occur whenever the driving
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
Page 10 of 17
ISL4238E, ISL4244E, ISL4245E
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).
INVALID switches high 1µs after detecting a valid RS-232
level on a receiver input. INVALID operates in all modes
(forced or automatic power-down, or forced on), so it is also
useful for systems employing manual power-down circuitry.=
2.7V
VALID RS-232 LEVEL - INVALID = 1
INDETERMINATE
FORCEOFF
T_IN
EDGE
DETECT
S
R_IN
30sec
TIMER
EDGE
DETECT
AUTOPWDN
R
FORCEON
FIGURE 7. ENHANCED AUTOMATIC POWER-DOWN LOGIC
The INVALID output signal switches low to indicate that invalid
levels have persisted on all of the receiver inputs for more than
30µs (see Figure 9), but this has no direct effect on the state of
the ISL4238E, ISL4244E, ISL4245 (see the next sections for
methods of utilizing INVALID to power down the device).
The time to recover from automatic power-down mode is
typically 100µs.
0.3V
INVALID LEVEL - INVALID = 0
-0.3V
INDETERMINATE
-2.7V
VALID RS-232 LEVEL - INVALID = 1
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS
Enhanced Automatic Power-down
Even greater power savings is available by using these devices
which feature an enhanced automatic power-down function.
When the enhanced power-down logic determines that no
transitions have occurred on any of the transmitter nor receiver
inputs for 30 seconds, the charge pump and transmitters
power-down, thereby reducing supply current to 10nA. The
ISL4238E, ISL4244E, ISL4245 automatically powers back up
whenever it detects a transition on one of these inputs. This
automatic power-down feature provides additional system
power savings without changes to the existing operating
system.
Enhanced automatic power-down operates when the
FORCEON input is low, and the FORCEOFF input is high.
Tying FORCEON high disables automatic power-down, but
manual power-down is always available via the overriding
FORCEOFF input. Table 2 summarizes the enhanced
automatic power-down functionality.
Figure 7 illustrates the enhanced power-down control logic.
Note that once the ISL4238E, ISL4244E, ISL4245 enters
power-down (manually or automatically), the 30 second
timer remains timed out (set), keeping the ISL4238E,
ISL4244E, ISL4245 powered down until FORCEON
transitions high, or until a transition occurs on a receiver or
transmitter input.
FN8038 Rev 5.00
May 13, 2010
Emulating Standard Automatic Power-down
If enhanced automatic power-down isn’t desired, the user can
implement the standard automatic power-down feature (mimics
the function on the ISL4243E) by connecting the INVALID
output to the FORCEON and FORCEOFF inputs, as shown in
Figure 8. After 30µs of invalid receiver levels, INVALID switches
low and drives the ISL4238E, ISL4244E, ISL4245 into a forced
power-down condition. INVALID switches high as soon as a
receiver input senses a valid RS-232 level, forcing the
ISL4238E, ISL4244E, ISL4245 to power on. See the “INVALID
DRIVING FORCEON AND FORCEOFF” section of Table 2 for
an operational summary. This operational mode is perfect for
handheld devices that communicate with another computer via
a detachable cable. Detaching the cable allows the internal
receiver pull-down resistors to pull the inputs to GND (an invalid
RS-232 level), causing the 30µs timer to time-out and drive the
IC into power-down. Reconnecting the cable restores valid
levels, causing the IC to power back up.
FORCEON
INVALID
FORCEOFF
ISL4238E
ISL4244E
ISL4245
I/O
UART
CPU
FIGURE 8. CONNECTIONS FOR AUTOMATIC POWER-DOWN
WHEN NO VALID RECEIVER SIGNALS ARE
PRESENT
Page 11 of 17
ISL4238E, ISL4244E, ISL4245E
RECEIVER
INPUTS
INVALID
} REGION
TRANSMITTER
INPUTS
TRANSMITTER
OUTPUTS
tINVH
INVALID
OUTPUT
tINVL
tAUTOPWDN
tAUTOPWDN
tWU
tWU
OUTPUT
V+
VCC
0
V-
FIGURE 9. ENHANCED AUTOMATIC POWER-DOWN AND INVALID TIMING DIAGRAMS
Hybrid Automatic Power-down Options
For devices which communicate only through a detachable
cable, connecting INVALID to FORCEOFF (with
FORCEON = 0) may be a desirable configuration. While the
cable is attached INVALID and FORCEOFF remain high, so the
enhanced automatic power-down logic powers down the RS232 device whenever there is 30 seconds of inactivity on the
receiver and transmitter inputs. Detaching the cable allows the
receiver inputs to drop to an invalid level (GND), so INVALID
switches low and forces the RS-232 device to power down. The
ISL4238E, ISL4244E, ISL4245 remains powered down until the
cable is reconnected (INVALID = FORCEOFF = 1) and a
transition occurs on a receiver or transmitter input (see Figure
7). For immediate power up when the cable is reattached,
connect FORCEON to FORCEOFF through a network similar
to that shown in Figure 5.
Capacitor Selection
The ISL4238E charge pumps require 0.1F, or greater,
capacitors for 3.3V (5% tolerance) operation. For other
supply voltages refer to Table 3 for capacitor values. Do not
use values smaller than those listed in Table 3.
TABLE 3. REQUIRED CAPACITOR VALUES (ISL4238E)
VCC (V)
C1 (µF)
C2, C3, C4 (µF)
3.0 to 3.6 (3.3V ±10%)
0.22
0.22
3.15 to 3.6 (3.3V ±5%)
0.1
0.1
4.5 to 5.5
0.047
0.33
3.0 to 5.5
0.22
1
The ISL4244E/45E charge pumps require 0.1µF capacitors
for proper operation. Increasing the capacitor values (by a
factor of 2) reduces ripple on the transmitter outputs and
FN8038 Rev 5.00
May 13, 2010
slightly reduces power consumption. C2, C3, and C4 can be
increased without increasing C1’s value, however, do not
increase C1 without also increasing C2, C3, and C4 to
maintain the proper ratios (C1 to the other capacitors).
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-.
Power Supply Decoupling
In most circumstances a 0.1µF bypass capacitor is
adequate. In applications that are particularly sensitive to
power supply noise, decouple VCC to ground with a
capacitor of the same value as the charge-pump capacitor C1.
Connect the bypass capacitor as close as possible to the IC.
Transmitter Outputs when Exiting
Power-down
Figure 10 shows the response of two transmitter outputs
when exiting power-down 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 3kin parallel with 2500pF. Note
that the transmitters enable only when the magnitude of the
supplies exceed approximately 3V.
Operation Down to 2.7V
ISL4238E, ISL4244E, ISL4245 transmitter outputs meet
RS-562 levels (±3.7V), at the full data rate, with VCC as low
as 2.7V. RS-562 levels typically ensure interoperability with
RS-232 devices.
Page 12 of 17
ISL4238E, ISL4244E, ISL4245E
5V/DIV
ISL4245E loopback results for a single transmitter driving
250pF and an RS-232 load at 1Mbps. The static transmitters
were also loaded with an RS-232 receiver.
FORCEOFF
T1
VCC
+
0.1µF
2V/DIV
+
C1
VCC
C1+
V+
C1T2
C2
+
VCC = +3.3V
C1 to C4 = 0.1µF
ISL4238E
ISL4244E
ISL4245
V-
C2TIN
TIME (20µs/DIV)
FIGURE 10. TRANSMITTER OUTPUTS WHEN EXITING
POWER-DOWN
RIN
FORCEON
The ISL424XE are specifically designed to power a serial
mouse while operating from low voltage supplies. Figure 11
shows the transmitter output voltages under increasing load
current. The on-chip switching regulator ensures the
transmitters will supply at least ±5V during worst case
conditions (15mA for paralleled V+ transmitters, 7.3mA for
single V- transmitter).
6
VCC
C4
+
TOUT
ROUT
Mouse Driveability
TRANSMITTER OUTPUT VOLTAGE (V)
C2+
+
C3
CL
5k
FORCEOFF
FIGURE 12. TRANSMITTER LOOPBACK TEST CIRCUIT
5V/DIV.
T1IN
5
VOUT+
4
VCC = 3.0V
3
2
T1OUT
T1
1
VOUT+
0
T2
-1
ISL424XE
-2
VCC
-3
R1OUT
VOUT -
T3
VCC = +3.3V
C1 to C4 = 0.1µF
VOUT -
-4
5µs/DIV
-5
-6
FIGURE 13. ISL4238E/ISL4244E LOOPBACK TEST AT 120kbps
0
1
2
3
4
5
6
7
8
9
10
LOAD CURRENT PER TRANSMITTER (mA)
FIGURE 11. TRANSMITTER OUTPUT VOLTAGE vs LOAD
CURRENT (PER TRANSMITTER, i.e., DOUBLE
CURRENT AXIS FOR TOTAL VOUT+ CURRENT)
5V/DIV.
T1IN
High Data Rates
The ISL4238E, ISL4244E, ISL4245 maintain the RS-232
±5V minimum transmitter output voltages even at high data
rates. Figure 12 details a transmitter loopback test circuit,
and Figure 13 illustrates the ISL4238E/ISL4244E loopback
test result at 120kbps. For this test, all transmitters were
simultaneously driving RS-232 loads in parallel with 1000pF,
at 120kbps. Figure 14 shows the ISL4238E/ISL4244E
loopback results for a single transmitter driving 1000pF and
an RS-232 load at 250kbps. Figure 15 illustrates the
ISL4245E loopback test result at 250kbps. For this test, all
transmitters were simultaneously driving RS-232 loads in
parallel with 1000pF, at 250kbps. Figure 16 shows the
FN8038 Rev 5.00
May 13, 2010
T1OUT
R1OUT
VCC = +3.3V
C1 - C4 = 0.1µF
2µs/DIV.
FIGURE 14. ISL4238E/ISL4244E LOOPBACK TEST AT
250kbps (CL = 1000pF)
Page 13 of 17
ISL4238E, ISL4244E, ISL4245E
±15kV ESD Protection
5V/DIV.
All pins on ISL4238E, ISL4244E, ISL4245 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.
T1IN
T1OUT
R1OUT
VCC = +3.3V
C1 - C4 = 0.1µF
2µs/DIV.
FIGURE 15. ISL4245E LOOPBACK TEST AT 250kbps
5V/DIV.
T1IN
T1OUT
Human Body Model (HBM) Testing
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 1.5k current limiting resistor,
making the test less severe than the IEC61000 test which
utilizes a 330 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.
IEC61000-4-2 Testing
R1OUT
VCC = +3.3V
C1 - C4 = 0.1µF
0.5µs/DIV.
FIGURE 16. ISL4245E LOOPBACK TEST AT 1Mbps
(CL = 250pF)
Interconnection with 3V and 5V Logic
The ISL4238E, ISL4244E, ISL4245 directly interface with 5V
CMOS and TTL logic families. Nevertheless, with the
ISL4238E, ISL4244E, ISL4245 at 3.3V, and the logic supply
at 5V, AC, HC, and CD4000 outputs can drive ISL4238E,
ISL4244E, ISL4245 inputs, but ISL4238E, ISL4244E,
ISL4245 outputs do not reach the minimum VIH for these
logic families. See Table 4 for more information.
TABLE 4. LOGIC FAMILY COMPATIBILITY WITH VARIOUS
SUPPLY VOLTAGES
VCC
SYSTEM
POWER-SUPPLY SUPPLY
VOLTAGE
VOLTAGE
(V)
(V)
COMPATIBILITY
3.3
3.3
Compatible with all CMOS families.
5
5
Compatible with all TTL and CMOS
logic families.
5
3.3
FN8038 Rev 5.00
May 13, 2010
Compatible with ACT and HCT
CMOS, and with TTL. ISL4238E,
ISL4244E, ISL4245 outputs are
incompatible with AC, HC, and
CD4000 CMOS inputs.
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.
AIR-GAP DISCHARGE TEST METHOD
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.
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.
Page 14 of 17
ISL4238E, ISL4244E, ISL4245E
Typical Performance Curves
VCC = 3.3V, TA = +25°C
6
TRANSMITTER OUTPUT VOLTAGE (V)
TRANSMITTER OUTPUT VOLTAGE (V)
6
VOUT+
4
2
1 TRANSMITTER AT 250kbps
OTHER TRANSMITTERS AT 30kbps
0
-2
VOUT -
-4
-6
0
1000
2000
3000
4000
VOUT+
4
2
0
-2
-4
-6
5000
1 TRANSMITTER AT 250kbps
OTHER TRANSMITTERS AT 30kbps
VOUT -
0
1000
LOAD CAPACITANCE (pF)
5000
55
VOUT+
1 TRANSMITTER AT INDICATED RATE
50
4
2
SUPPLY CURRENT (mA)
TRANSMITTER OUTPUT VOLTAGE (V)
4000
FIGURE 18. ISL4244E TRANSMITTER OUTPUT VOLTAGE vs
LOAD CAPACITANCE
6
1 TRANSMITTER AT 1Mbps
OTHER TRANSMITTERS AT 30kbps
0
-2
VOUT -
-4
0
1000
2000
3000
4000
45
250kbps
40
120kbps
35
30
25
20kbps
20
5000
0
1000
LOAD CAPACITANCE (pF)
45
2000
4000
3000
FIGURE 20. ISL4238E SUPPLY CURRENT vs LOAD
CAPACITANCE WHEN TRANSMITTING DATA
90
1 TRANSMITTER AT INDICATED RATE
1 TRANSMITTER AT INDICATED RATE
80
40
SUPPLY CURRENT (mA)
250kbps
35
30
120kbps
25
20
20kbps
15
5000
LOAD CAPACITANCE (pF)
FIGURE 19. ISL4245E TRANSMITTER OUTPUT VOLTAGE vs
LOAD CAPACITANCE
SUPPLY CURRENT (mA)
3000
LOAD CAPACITANCE (pF)
FIGURE 17. ISL4238E TRANSMITTER OUTPUT VOLTAGE vs
LOAD CAPACITANCE
-6
2000
1Mbps
70
60
50
250kbps
40
30
120kbps
20
10
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
FIGURE 21. ISL4244E SUPPLY CURRENT vs LOAD
CAPACITANCE WHEN TRANSMITTING DATA
FN8038 Rev 5.00
May 13, 2010
10
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
FIGURE 22. ISL4245E SUPPLY CURRENT vs LOAD
CAPACITANCE WHEN TRANSMITTING DATA
Page 15 of 17
ISL4238E, ISL4244E, ISL4245E
Typical Performance Curves
VCC = 3.3V, TA = +25°C (Continued)
25
110
90
+SLEW
-SLEW
SLEW RATE (V/µs)
SLEW RATE (V/µs)
20
15
+SLEW
10
70
50
-SLEW
30
10
5
0
1000
2000
3000
4000
5000
0
0
1000
LOAD CAPACITANCE (pF)
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
FIGURE 23. ISL4238E/ISL4244E SLEW RATE vs LOAD
CAPACITANCE
FIGURE 24. ISL4245E SLEW RATE vs LOAD CAPACITANCE
Die Characteristics
3.5
NO LOAD
ALL OUTPUTS STATIC
SUPPLY CURRENT (mA)
3.0
SUBSTRATE AND QFN THERMAL PAD POTENTIAL
(POWERED UP):
GND
TRANSISTOR COUNT
2.5
ISL4238E: 1235
ISL4244E: 1109
ISL4245E: 1109
2.0
1.5
PROCESS
Si Gate BiCMOS
1.0
0.5
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
SUPPLY VOLTAGE (V)
FIGURE 25. SUPPLY CURRENT vs SUPPLY VOLTAGE
© Copyright Intersil Americas LLC 2002-2010. All Rights Reserved.
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For additional products, see www.intersil.com/en/products.html
Intersil products are manufactured, assembled and tested utilizing ISO9001 quality systems as noted
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Intersil products are sold by description only. Intersil may modify the circuit design and/or specifications of products at any time without notice, provided that such
modification does not, in Intersil's sole judgment, affect the form, fit or function of the product. Accordingly, the reader is cautioned to verify that datasheets 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
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For information regarding Intersil Corporation and its products, see www.intersil.com
FN8038 Rev 5.00
May 13, 2010
Page 16 of 17
ISL4238E, ISL4244E, ISL4245E
Package Outline Drawing
L32.5x5B
32 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 2, 11/07
4X 3.5
5.00
28X 0.50
A
B
6
PIN 1
INDEX AREA
6
PIN #1 INDEX AREA
32
25
1
5.00
24
3 .30 ± 0 . 15
17
(4X)
8
0.15
9
16
TOP VIEW
0.10 M C A B
+ 0.07
32X 0.40 ± 0.10
4 32X 0.23 - 0.05
BOTTOM VIEW
SEE DETAIL "X"
0.10 C
0 . 90 ± 0.1
C
BASE PLANE
SEATING PLANE
0.08 C
( 4. 80 TYP )
(
( 28X 0 . 5 )
SIDE VIEW
3. 30 )
(32X 0 . 23 )
C
0 . 2 REF
5
( 32X 0 . 60)
0 . 00 MIN.
0 . 05 MAX.
DETAIL "X"
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
5. Tiebar shown (if present) is a non-functional feature.
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.
FN8038 Rev 5.00
May 13, 2010
Page 17 of 17
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