DATASHEET
ISL4241E, ISL4243E
FN8037
Rev 7.00
Jun 10, 2010
QFN Packaged, ±15kV ESD Protected, +2.7V to +5.5V, 10Nanoamp, 250kbps,
RS-232 Transmitters/Receivers
Intersil’s ISL4241E, ISL4243E 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 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 are guaranteed at worst case load conditions.
Features
The ISL4241E, ISL4243E’s are 3 driver, 5 receiver devices
that, coupled with the 5x5 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 Ld
TSSOP, and is nearly 20% thinner. The devices also include
a noninverting always-active receiver for “wake-up”
capability.
• Receiver Hysteresis For Improved Noise Immunity
The ISL4243E features an automatic power-down 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.
Table 1 summarizes the features of both the ISL4241E and
ISL4243E, while Application Note AN9863 summarizes the
features of each device comprising the 3V RS-232 family.
• Pb-Free Available (RoHS compliant)
• Parameters Fully Specified for 10% Tolerance Supplies
and Full Industrial Temp Range
• Available in Small QFN (5mmx5mm) Package which is
60% Smaller than a 28 Lead TSSOP
• ESD Protection for RS-232 I/O Pins to ±15kV (IEC61000)
• Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V
• RS-232 Compatible with VCC = 2.7V
• On-Chip Voltage Converters Require Only Four External
0.1µF Capacitors
• Manual and Automatic Power-down Features
• Guaranteed Minimum Data Rate . . . . . . . . . . . . . 250kbps
• Wide Power Supply Range . . . . . . Single +2.7V to +5.5V
• Low Supply Current in Power-down State . . . . . . . . .10nA
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”
TABLE 1. SUMMARY OF FEATURES
PART NUMBER
NO. OF NO. OF
Tx.
Rx.
NO. OF
MONITOR Rx.
QFN PKG.
(ROUTB)
AVAILABLE?
DATA
RATE
(kbps)
Rx. ENABLE
FUNCTION?
READY
OUTPUT?
MANUAL
POWERDOWN?
AUTOMATIC
POWERDOWN
FUNCTION?
ISL4241E
3
5
YES
2
250
YES
NO
YES
NO
ISL4243E
3
5
YES
1
250
NO
NO
YES
YES
FN8037 Rev 7.00
Jun 10, 2010
Page 1 of 14
ISL4241E, ISL4243E
Ordering Information
PART
NUMBER
TEMP. RANGE
(°C)
PART MARKING
PACKAGE
PKG. DWG. #
ISL4241EIR
ISL 4241EIR
-40 to +85
32 Ld QFN
L32.5x5B
ISL4241EIR-T*
ISL 4241EIR
-40 to +85
32 Ld QFN
Tape & Reel
L32.5x5B
ISL4241EIRZ (Note)
ISL4241 EIRZ
-40 to +85
32 Ld QFN (Pb-Free)
L32.5x5B
ISL4241EIRZ-T* (Note)
ISL4241 EIRZ
-40 to +85
32 Ld QFN
Tape & Reel (Pb-Free)
L32.5x5B
ISL4243EIR
ISL 4243EIR
-40 to +85
32 Ld QFN
L32.5x5B
ISL4243EIR-T*
ISL 4243EIR
-40 to +85
32 Ld QFN
Tape & Reel
L32.5x5B
ISL4243EIRZ (Note)
ISL4243 EIRZ
-40 to +85
32 Ld QFN (Pb-Free)
L32.5x5B
ISL4243EIRZ-T* (Note)
ISL4243 EIRZ
-40 to +85
32 Ld 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.
Pinouts
32
31
30
29
28
NC
C2-
25
VCC
V-
26
V+
NC
27
C1+
NC
28
VCC
29
V+
C230
C1+
V31
C2+
NC
32
C2+
ISL4243E
(32 LD QFN)
TOP VIEW
ISL4241E
(32 LD QFN)
TOP VIEW
27
26
25
R1IN
1
24
GND
R1IN
1
24
GND
R2IN
2
23
C1-
R2IN
2
23
C1-
R3IN
3
22
EN
R3IN
3
22
FORCEON
R4IN
4
21
SHDN
R4IN
4
21
FORCEOFF
R5IN
5
20
R1OUTB
R5IN
5
20
INVALID
T1OUT
6
19
R2OUTB
T1OUT
6
19
R2OUTB
T2OUT
7
18
R1OUT
T2OUT
7
18
R1OUT
T3OUT
8
17
R2OUT
T3OUT
8
17
R2OUT
12
13
14
15
16
NC
NC
11
R3OUT
R3OUT
10
R4OUT
R4OUT
9
R5OUT
16
T1IN
15
T2IN
14
T3IN
13
NC
12
R5OUT
T3IN
FN8037 Rev 7.00
Jun 10, 2010
11
T1IN
10
T2IN
9
NC
PD
PD
Page 2 of 14
ISL4241E, ISL4243E
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.
TOUT
RIN
ROUT
ROUTB
INVALID
±15kV ESD Protected, RS-232 level (nominally ±5.5V) transmitter outputs.
±15kV ESD Protected, RS-232 compatible receiver inputs.
TTL/CMOS level receiver outputs.
TTL/CMOS level, noninverting, always enabled receiver outputs.
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
EN
SHDN
Active high input to override automatic power-down circuitry thereby keeping transmitters active. (FORCEOFF must be high).
Active low receiver enable control.
Active low input to shut down transmitters and on-board power supply, to place device in low power mode.
NC
No Connection
PD
Exposed Thermal Pad. Connect to GND.
FN8037 Rev 7.00
Jun 10, 2010
Page 3 of 14
ISL4241E, ISL4243E
Typical Operating Circuits
ISL4241E
+3.3V
+
C1
0.1µF
C2
0.1µF
T1IN
T2IN
T3IN
R1OUTB
R2OUTB
TTL/CMOS
LOGIC
LEVELS
R1OUT
+3.3V
0.1µF
28
C1+
+
23
C129
C2+
+
30
C212
VCC
V+
VT1
11
T2
10
T3
27
31
C1
0.1µF
C2
0.1µF
C4
0.1µF
+
T1OUT
7
8
T2OUT
T1IN
RS-232
LEVELS
T2IN
T3OUT
T3IN
19
28
+
C1+
26
27
VCC
V+
23
C129
C2+
+
30
C2-
V-
12
T1
11
T2
C3
0.1µF
C4
0.1µF
+
6
T1OUT
7
T2OUT
T3
10
31
+
RS-232
LEVELS
8
T3OUT
R2OUTB
18
1
17
TTL/CMOS
LOGIC
LEVELS
R2IN
5k
R2OUT
4
R4OUT
R4
17
13
RS-232
LEVELS
15
R4OUT
5k
R5
R3IN
5k
14
R5OUT
4
GND
24
VCC
TO POWER
CONTROL
LOGIC
21
20
RS-232
LEVELS
R4IN
5k
13
22
SHDN
3
R4
R5IN
R2IN
5k
R3OUT
5
EN
2
R3
R4IN
5k
R1IN
5k
R2
R3IN
5k
1
R1
3
14
21
R1OUT
2
R3
22
18
R1IN
5k
R3OUT
FN8037 Rev 7.00
Jun 10, 2010
0.1µF
19
15
VCC
+ C3
0.1µF
6
20
R2
R5OUT
+
26
R1
R2OUT
ISL4243E
5
5k
R5
R5IN
FORCEON
FORCEOFF
INVALID
GND
24
Page 4 of 14
ISL4241E, ISL4243E
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, EN, SHDN . . . . . . . . . -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 7
Thermal Resistance (Typical, Notes 1, 2) JA (°C/W)
JC (°C/W)
32 Ld QFN Package. . . . . . . . . . . . . . .
32
2.0
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
ISL4241EIR, ISL4243EIR . . . . . . . . . . . . . . . . . . .-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: 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 4)
TYP
MAX
(Note 4) UNITS
Full
2.7
-
5.5
V
DC CHARACTERISTICS
Operating Voltage Range
Supply Current, Automatic
Power-down
All RIN Open, FORCEON = GND, FORCEOFF = VCC
(ISL4243E Only)
Supply Current, Power-down
All RIN Open, FORCEOFF = SHDN = GND
Supply Current,
Automatic Power-down Disabled
All Outputs Unloaded,
FORCEON = FORCEOFF = SHDN = VCC, VCC = 3.0V
25
-
3
300
nA
Full
-
50
300
nA
25
-
3
300
nA
Full
-
50
300
nA
25
-
0.3
1.0
mA
Full
-
0.3
1.5
mA
Full
-
-
0.8
V
LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
TIN, FORCEON, FORCEOFF, EN, SHDN
Input Logic Threshold High
TIN, FORCEON, FORCEOFF, EN, SHDN, VCC = 3.6V
Full
2.0
-
-
V
Input Leakage Current
TIN, FORCEON, FORCEOFF, EN, SHDN
Full
-
±0.01
±1.0
µA
Output Leakage Current
FORCEOFF = GND (ISL4243E) or EN = VCC (ISL4241E)
Full
-
±0.05
±10
µA
25
-
0.5
-
V
-
-
0.4
V
-
V
Transmitter Input Hysteresis
Output Voltage Low
IOUT = 1.6mA
Full
Output Voltage High
IOUT = -1.0mA
Full
VCC - 0.6 VCC - 0.1
AUTOMATIC POWER-DOWN (ISL4243E Only, FORCEON = GND, FORCEOFF = VCC)
Receiver Input Thresholds to
Enable Transmitters
ISL4243E Powers Up (see Figure 7)
Full
-2.7
-
2.7
V
Receiver Input Thresholds to
Disable Transmitters
ISL4243E Powers Down (see Figure7)
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
Full
-
20
100
µs
Receiver Threshold to Transmitters
Enabled Delay (tWU)
FN8037 Rev 7.00
Jun 10, 2010
Page 5 of 14
ISL4241E, ISL4243E
Electrical Specifications
Test Conditions: VCC = 3V to 5.5V, C1 to C4 = 0.1µF; Unless Otherwise Specified.
Typicals are at TA = +25°C (Continued)
PARAMETER
TEST CONDITIONS
Receiver Positive or Negative
Threshold to INVALID High Delay
(tINVH)
Receiver Positive or Negative
Threshold to INVALID Low Delay
(tINVL)
TEMP
(°C)
MIN
(Note 4)
TYP
MAX
(Note 4) UNITS
25
-
0.5
1
µs
Full
-
0.9
1.5
µs
25
-
30
50
µs
Full
-
40
60
µs
RECEIVER INPUTS
Input Voltage Range
Full
-25
-
25
V
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
TRANSMITTER OUTPUTS
Output Voltage Swing
All Transmitter Outputs Loaded with 3k to Ground
Full
±5.0
±5.4
-
V
Output Resistance
VCC = V+ = V- = 0V, Transmitter Output = ±2V
Full
300
10M
-
Full
-
±35
±60
mA
VOUT = ±12V, VCC = 0V or 3V to 5.5V,
Automatic Power-down or FORCEOFF = SHDN = GND
Full
-
-
±25
µA
Maximum Data Rate
RL = 3kCL = 1000pF, One Transmitter Switching
Full
250
500
-
kbps
Receiver Propagation Delay
Receiver Input to Receiver Output,
CL = 150pF
25
-
0.15
0.3
µs
Full
-
0.2
0.35
µs
Output Short-Circuit Current
Output Leakage Current
TIMING CHARACTERISTICS
tPHL
tPLH
Receiver Skew
Transmitter Propagation Delay
tPHL - tPLH, CL = 150pF
Transmitter Input to Transmitter Output,
CL = 1000pF, RL = 3k
tPHL
tPLH
Transmitter Skew
Receiver Output Enable Time
Receiver Output Disable Time
Transmitter Output Enable Time
Transmitter Output Disable Time
FN8037 Rev 7.00
Jun 10, 2010
tPHL - tPLH (Note 3), RL = 3k, CL = 1000pF
Normal Operation, RL = 1k to 0.5VCC, CL = 15pF
Normal Operation, RL = 1k to 0.5VCC, CL = 15pF
Normal Operation, RL = 3k, CL = 1000pF
Normal Operation, RL = 3k, CL = 1000pF
25
-
0.3
0.5
µs
Full
-
0.35
0.55
µs
25
-
120
250
ns
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
-
200
350
ns
Full
-
200
400
ns
25
-
350
500
ns
Full
-
400
600
ns
25
-
25
40
µs
Full
-
30
50
µs
25
-
2.5
4
µs
Full
-
2.7
4
µs
Page 6 of 14
ISL4241E, ISL4243E
Electrical Specifications
PARAMETER
Transition Region Slew Rate
Test Conditions: VCC = 3V to 5.5V, C1 to C4 = 0.1µF; Unless Otherwise Specified.
Typicals are at TA = +25°C (Continued)
TEMP
(°C)
MIN
(Note 4)
TYP
25
4
9
30
V/µs
Full
4
8
30
V/µs
25
6
11
30
V/µs
Full
6
10
30
V/µs
Human Body Model
25
-
±15
-
kV
IEC61000-4-2 Contact Discharge
25
-
±8
-
kV
TEST CONDITIONS
VCC = 3V to 3.6V, RL = 3kto 7k
Measured From 3V to -3V or -3V to 3V
CL = 150pF to
2500pF
CL = 150pF to
1000pF
MAX
(Note 4) UNITS
ESD PERFORMANCE
RS-232 Pins (TOUT, RIN)
All Other Pins
IEC61000-4-2 Air Gap Discharge
25
-
±15
-
kV
Human Body Model
25
-
±2
-
kV
NOTE:
3. Transmitter skew is measured at the transmitter zero crossing points.
4. 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
The ISL4241E and ISL4243E both 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 specifications even with VCC = 3.0V. The circuit is
divided into three sections: The charge pump, the
transmitters, and the receivers.
Charge-Pump
Intersil’s new ISL4241E, ISL4243E devices utilize 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 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+
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.
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.
transmitter operating at full speed. Under more typical
conditions of VCC 3.3V, RL = 3k, and CL = 250pF, one
transmitter easily operates at 900kbps.
Transmitter inputs float if left unconnected, and may cause
ICC increases. Connect unused inputs to GND for the best
performance.
Receivers
All the ISL4241E, ISL4243E’s devices contain standard
inverting receivers that are three-state via the EN or
FORCEOFF control lines. Additionally, the ISL4241E,
ISL4243E’s 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 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
RXIN
-25V VRIN +25V
RXOUT
5k
GND VROUT VCC
GND
FIGURE 1. INVERTING RECEIVER CONNECTIONS
The ISL4241E inverting receivers disable only when EN is
driven high. ISL4243E receivers disable during forced
(manual) power-down, but not during automatic power-down
(see Table 2).
The devices guarantee a 250kbps data rate for full load
conditions (3k and 1000pF), VCC 3.0V, with one
FN8037 Rev 7.00
Jun 10, 2010
Page 7 of 14
ISL4241E, ISL4243E
TABLE 2. POWER-DOWN AND ENABLE LOGIC TRUTH TABLE
RS-232
SIGNAL
PRESENT
AT
RECEIVER
INPUT?
SHDN OR
FORCEOFF FORCEON
EN
TRANSMITTER RECEIVER
ROUTB
INVALID
INPUT
INPUT
INPUT
OUTPUTS
OUTPUTS OUTPUTS OUTPUT
MODE OF OPERATION
ISL4241E
N.A.
L
N/A
L
High-Z
Active
Active
N/A
Manual Power-down
N.A.
L
N/A
H
High-Z
High-Z
Active
N/A
Manual Power-down w/Receiver
Disabled
N.A.
H
N/A
L
Active
Active
Active
N/A
Normal Operation
N.A.
H
N/A
H
Active
High-Z
Active
N/A
Normal Operation w/Receiver
Disabled
NO
H
H
N/A
Active
Active
Active
L
Normal Operation
(Auto Power-down Disabled)
YES
H
L
N/A
Active
Active
Active
H
Normal Operation
(Auto Power-down Enabled)
NO
H
L
N/A
High-Z
Active
Active
L
Power-down Due to Auto Power-down
Logic
YES
L
X
N/A
High-Z
High-Z
Active
H
Manual Power-down
NO
L
X
N/A
High-Z
High-Z
Active
L
Manual Power-down
ISL4243E
ISL4241E and ISL4243E monitor receivers remain active
even during manual power-down, making them 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 renders them useless for
wake-up functions, but the corresponding monitor receiver
can be dedicated to this task as shown in Figure 3.
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.
VCC
VCC
CURRENT
FLOW
VCC
VOUT = VCC
Rx
POWERED
DOWN
UART
Tx
GND
SHDN = GND
OLD
RS-232 CHIP
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN
PERIPHERAL
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 three-state. Inverting receiver
outputs disable only in manual power-down; refer to Table 2
for details. This micro-power mode makes the ISL4241E and
ISL4243E ideal for battery powered and portable
applications.
FN8037 Rev 7.00
Jun 10, 2010
Page 8 of 14
ISL4241E, ISL4243E
VCC
FORCEOFF
PWR
MGT
LOGIC
TRANSITION
DETECTOR
TO
WAKE-UP
LOGIC
FORCEON
INVALID
ISL4241E
ISL4243E
ISL4243E
VCC
R2OUTB
RX
POWERED
DOWN
UART
VOUT = HI-Z
R2OUT
TX
I/O
UART
R2IN
CPU
T1IN
FORCEOFF = GND
OR
SHDN = GND, EN = VCC
T1OUT
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
FIGURE 4. CONNECTIONS FOR MANUAL POWER-DOWN
WHEN NO VALID RECEIVER SIGNALS ARE
PRESENT
Software Controlled (Manual) Power-down
Most devices in the ISL4241E, ISL4243E family provide pins
that allow the user to force the IC into the low power, standby
state.
On the ISL4241E, the power-down control is via a simple
shutdown (SHDN) pin. Driving this pin high enables normal
operation, while driving it low forces the IC into it’s
power-down state. Connect SHDN to VCC if the power-down
function isn’t needed. Note that all the receiver outputs
remain enabled during shutdown (see Table 2). For the
lowest power consumption during power-down, the receivers
should also be disabled by driving the EN input high (see
next section, and Figures 2 and 3).
The ISL4243E 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 automatic power-down circuitry. The ISL4243E
inverting (standard) receiver outputs also disable when the
device is in manual power-down, 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 automatic power-down feature, enabling them to function
as a manual SHUTDOWN input (see Figure 4).
FN8037 Rev 7.00
Jun 10, 2010
With any of the previous mentioned control schemes, the
time required to exit power-down, and resume transmission
is only 100µs. A mouse, or other application, may need more
time to wake up from shutdown. If automatic power-down is
being utilized, the RS-232 device will reenter power-down if
valid receiver levels aren’t reestablished within 30µs of the
ISL4243E powering up. Figure 5 illustrates a circuit that
keeps the ISL4243E from initiating automatic power-down
for 100ms after powering up. This gives the slow-to-wake
peripheral circuit time to reestablish valid RS-232 output
levels.
POWER
MANAGEMENT
UNIT
MASTER POWER-DOWN LINE
0.1µF
FORCEOFF
1M
FORCEON
ISL4243E
FIGURE 5. CIRCUIT TO PREVENT AUTO POWER-DOWN
FOR 100ms AFTER FORCED POWERUP
INVALID Output (ISL4243E Only)
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
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
Page 9 of 14
ISL4241E, ISL4243E
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).
2.7V
VALID RS-232 LEVEL - ISL4243E IS ACTIVE
INDETERMINATE - POWER-DOWN MAY OR
MAY NOT OCCUR
0.3V
INVALID LEVEL - POWER-DOWN OCCURS AFTER 30µs
-0.3V
INDETERMINATE - POWER-DOWN MAY OR
MAY NOT OCCUR
VALID RS-232 LEVEL - ISL4243E IS ACTIVE
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS
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 power-down, or forced on), so it
is also useful for systems employing manual power-down
circuitry. When automatic power-down is utilized, INVALID = 0
indicates that the ISL4243E is in power-down mode.
INVALID
} REGION
TRANSMITTER
OUTPUTS
INVALID
OUTPUT
VCC
0
tINVL
The time to recover from automatic power-down mode is
typically 100µs.
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.
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
tINVH
AUTOPWDN
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 automatic
power-down functionality.
Capacitor Selection
-2.7V
RECEIVER
INPUTS
peripheral’s outputs are shut off (powered down) or when the
RS-232 interface cable is disconnected. The ISL4243E
powers back up whenever it detects a valid RS-232 voltage
level on any receiver input. This automatic power-down
feature provides additional system power savings without
changes to the existing operating system.
PWR UP
V+
VCC
0
V-
Figure 8 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.
FIGURE 7. AUTOMATIC POWER-DOWN AND INVALID
TIMING DIAGRAMS
Automatic Power-down (ISL4243E Only)
Even greater power savings is available by using the
ISL4243E which features an automatic power-down
function. When no valid RS-232 voltages (see Figure 5) are
sensed on any receiver input for 30µs, the charge pump and
transmitters power-down, thereby reducing supply current to
10nA. Invalid receiver levels occur whenever the driving
FN8037 Rev 7.00
Jun 10, 2010
Page 10 of 14
ISL4241E, ISL4243E
5V/DIV
5V/DIV.
FORCEOFF
T1
T1IN
T1OUT
2V/DIV.
T2
R1OUT
VCC = +3.3V
C1 to C4 = 0.1 µF
VCC = +3.3V
C1 to C4 = 0.1µF
5µs/DIV
TIME (20µs/DIV)
FIGURE 10. LOOPBACK TEST AT 120kbps
FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING
POWER-DOWN
Operation Down to 2.7V
The ISL4241E, ISL4243E 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 inter operability with RS-232
devices.
High Data Rates
+
C1
VCC
C1+
V+
C1C2
+
C2+
ISL4241E
ISL4243E
V-
C2TIN
FORCEON
+
C3
C4
+
TOUT
RIN
ROUT
VCC
R1OUT
VCC = +3.3V
C1 - C4 = 0.µF
2µs/DIV
FIGURE 11. LOOPBACK TEST AT 250kbps
Interconnection with 3V and 5V Logic
+
0.1µF
T1IN
T1OUT
The ISL4241E, ISL4243E 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.
VCC
5V/DIV.
1000pF
5k
The ISL4241E, ISL4243E directly interface with 5V CMOS
and TTL logic families. Nevertheless, with the ISL4241E,
ISL4243E at 3.3V, and the logic supply at 5V, AC, HC, and
CD4000 outputs can drive ISL4241E, ISL4243E inputs, but
ISL4241E, ISL4243E outputs do not reach the minimum VIH
for these logic families. See Table 3 for more information.
TABLE 3. LOGIC FAMILY COMPATIBILITY WITH VARIOUS
SUPPLY VOLTAGES
VCC
SYSTEM
POWER-SUPPLY SUPPLY
VOLTAGE
VOLTAGE
(V)
(V)
3.3
3.3
5
5
FORCEOFF or SHDN
FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT
FN8037 Rev 7.00
Jun 10, 2010
COMPATIBILITY
Compatible with all CMOS
families.
Compatible with all TTL and
CMOS logic families.
Page 11 of 14
ISL4241E, ISL4243E
TABLE 3. LOGIC FAMILY COMPATIBILITY WITH VARIOUS
SUPPLY VOLTAGES (Continued)
VCC
SYSTEM
POWER-SUPPLY SUPPLY
VOLTAGE
VOLTAGE
(V)
(V)
5
3.3
respect to all other pins. The RS-232 pins on “E” family
devices can withstand HBM ESD events to 15kV.
IEC61000-4-2 Testing
COMPATIBILITY
Compatible with ACT and HCT
CMOS, and with TTL. ISL4241E,
ISL4243E outputs are
incompatible with AC, HC, and
CD4000 CMOS inputs.
±15kV ESD Protection
All pins on ISL4241E, ISL4243E 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.
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
Typical Performance Curves
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.
VCC = 3.3V, TA = +25°C
25
VOUT+
4
20
2
SLEW RATE (V/s)
TRANSMITTER OUTPUT VOLTAGE (V)
6
1 TRANSMITTER AT 250kbps
OTHER TRANSMITTERS AT 30kbps
0
-2
15
-SLEW
+SLEW
10
VOUT -
-4
-6
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
FIGURE 12. TRANSMITTER OUTPUT VOLTAGE vs LOAD
CAPACITANCE
FN8037 Rev 7.00
Jun 10, 2010
5
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
FIGURE 13. SLEW RATE vs LOAD CAPACITANCE
Page 12 of 14
ISL4241E, ISL4243E
VCC = 3.3V, TA = +25°C (Continued)
45
3.5
40
3.0
250kbps
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
Typical Performance Curves
35
30
120kbps
25
20
20kbps
15
NO LOAD
ALL OUTPUTS STATIC
2.5
2.0
1.5
1.0
0.5
10
0
2000
1000
3000
4000
5000
0
2.5
3.0
3.5
LOAD CAPACITANCE (pF)
FIGURE 14. SUPPLY CURRENT vs LOAD CAPACITANCE
WHEN TRANSMITTING DATA
4.0
4.5
5.0
5.5
6.0
SUPPLY VOLTAGE (V)
FIGURE 15. SUPPLY CURRENT vs SUPPLY VOLTAGE
Die Characteristics
SUBSTRATE AND QFN THERMAL PAD POTENTIAL
(POWERED UP):
GND
TRANSISTOR COUNT:
ISL4241E, ISL4243E: 464
PROCESS:
Si Gate BiCMOS
© Copyright Intersil Americas LLC 2002-2010. All Rights Reserved.
All trademarks and registered trademarks are the property of their respective owners.
For additional products, see www.intersil.com/en/products.html
Intersil products are manufactured, assembled and tested utilizing ISO9001 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
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
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
FN8037 Rev 7.00
Jun 10, 2010
Page 13 of 14
ISL4241E, ISL4243E
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.
FN8037 Rev 7.00
Jun 10, 2010
Page 14 of 14
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