Datasheet
ICL3237E
±15kV ESD Protected, 10nA Supply-Current, +3V to +5.5V, 250k/1Mbps,
RS-232 Transmitters/Receivers
The ICL3237E contains 3.0V to 5.5V powered
RS-232 transmitters/receivers that meet ElA/TIA-232
and V.28/V.24 specifications, even at VCC = 3.0V. It
provides ±15kV ESD protection (IEC61000-4-2 Air
Gap and Human Body Model) on transmitter outputs
and receiver inputs (RS-232 pins). Targeted
applications are cell phones, PDAs, Palmtops, and
notebook and laptop computers where the low
operational power and even lower standby power
consumption is critical. Efficient on-chip charge
pumps coupled with the manual powerdown function
reduce the standby supply current to a 10nA trickle.
Small footprint packaging and the use of small, low
value capacitors ensure board space savings. Data
rates greater than 1Mbps (MBAUD = VCC) are
ensured at worst case load conditions. The ICL3237E
is fully compatible with 3.3V only systems, mixed 3.3V
and 5.0V systems, and 5.0V only systems.
The ICL3237E is a 5 driver, 3 receiver device that also
includes a noninverting always-active receiver for
“wake-up” capability.
Table 1 summarizes the features of the ICL3237E.
Application Note AN9863 summarizes the features of
each device comprising the ICL32xx RS-232 3V
family.
Related Literature
Features
• Pb-free (RoHS compliant)
• ESD protection for RS-232 I/O pins to ±15kV
(IEC61000)
• Pin compatible replacement for MAX3237E
• Pin selectable, ensured data rate: 250kbps/1Mbps
• Meets EIA/TIA-232 and V.28/V.24 specifications
at 3V
• RS-232 compatible with VCC = 2.7V
• Latch-up free
• On-chip voltage converters require only
four external capacitors
• Manual powerdown feature
• Flow through pinout
• Rx and Tx hysteresis for improved noise immunity
• Rx active in powerdown; separate Rx Enable pin
• Guaranteed minimum slew rate: 6V/µs or 24V/µs
• Wide power supply range: Single +3V to +5.5V
• Low supply current in powerdown state: 10nA
Applications
• Any system requiring RS-232 communication ports
For a full list of related documents, visit our website:
• ICL3237E device page
○ Battery powered, hand-held, and portable
equipment
○ Laptop computers, notebooks, and Palmtops
○ Modems, printers and other peripherals
○ Data cradles and cables
○ Cellular/mobile phones
Table 1.
Summary of Features
Part Number
No. of
Tx.
No. of
Rx.
No. of Monitor
Rx. (ROUTB)
Data Rate
(kbps) (Note 1)
Rx. Enable
Function?
Ready
Output?
Manual
Powerdown?
Automatic
Powerdown
Function?
ICL3237E
5
3
1
250/1000
Yes
No
Yes
No
Note:
1. Data rate is selectable with the MBAUD pin.
FN6014 Rev.3.00
Apr.26.19
Page 1 of 21
ICL3237E
Contents
1.
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1
1.2
1.3
1.4
2.
Typical Operating Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pinout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
4
4
4
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1
2.2
2.3
2.4
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
6
6
6
3.
Typical Performance Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1
4.1.1
4.2
4.3
4.4
4.5
4.5.1
4.6
4.7
4.8
4.9
4.10
4.11
4.12
5.
Charge Pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charge Pump Abs Max Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation Down to 2.7V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Powerdown Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Software Controlled (Manual) Powerdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver ENABLE Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MegaBaud Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmitter Outputs when Exiting Powerdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Data Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interconnection with 3V and 5V Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
11
12
12
13
13
13
13
14
15
15
15
16
16
±15kV ESD Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1
5.2
5.3
5.4
Human Body Model (HBM) Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IEC61000-4-2 Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air-Gap Discharge Test Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contact Discharge Test Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
17
17
17
6.
Die Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
FN6014 Rev.3.00
Apr.26.19
Page 2 of 21
ICL3237E
1.
1.1
1. Overview
Overview
Typical Operating Circuit
ICL3237E
+
C1
0.1µF
Note 3
C2
0.1µF
T1IN
T2IN
C3 (Optional Connection, Note 2)
28
+
26
0.1µF
C1+
+
+3.3V
27
VCC
V+
25
C11
C2+
+
3
C2-
VT1
24
5
T2
23
6
T3
22
4
Note 3
C4
0.1µF
+
T1OUT
T2OUT
T3OUT
T4
19
10
T5
17
RS-232
Levels
T4OUT
12
T5IN
TTL/CMOS
Logic Levels
C3
0.1µF
7
T3IN
T4IN
+
T5OUT
16
R1OUTB
21
8
R1OUT
R1IN
5kΩ
R1
R2OUT
20
9
5kΩ
R2
18
R3IN
13
To Control Logic
RS-232
Levels
11
R3OUT
VCC
R2IN
14
15
EN
5kΩ
R3
SHDN
MBAUD
GND
2
Notes:
2. The negative terminal of C3 can be connected to either VCC or GND.
3. For VCC = 3.15V (3.3V -5%), Use C1 - C4 = 0.1µF or Greater. For VCC = 3.0V (3.3V - 10%), Use C1 - C4 = 0.22µF.
FN6014 Rev.3.00
Apr.26.19
Page 3 of 21
ICL3237E
1.2
1. Overview
Ordering Information
Part Number
(Notes 5, 6)
Part Marking
Temp. Range (°C)
Tape and Reel
(Units) (Note 4)
Package (RoHS
Compliant)
Pkg. Dwg. #
ICL3237ECAZ
ICL3237 ECAZ
0 to +70
-
28 Ld SSOP
M28.209
ICL3237ECAZ-T
ICL3237 ECAZ
0 to +70
1k
28 Ld SSOP
M28.209
ICL3237EIAZ
ICL3237 EIAZ
-40 to +85
28 Ld SSOP
M28.209
ICL3237EIAZ-T
ICL3237 EIAZ
-40 to +85
28 Ld SSOP
M28.209
1k
Notes:
4. See TB347 for details about reel specifications.
5. These Pb-free plastic packaged products employ special Pb-free material sets; molding compounds/die attach materials and NiPdAu-Ag
plate - e4 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations. 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.
6. For Moisture Sensitivity Level (MSL), see the ICL3237E device page. For more information about MSL, see TB363.
1.3
Pinout
28 Ld SSOP
Top View
28 C1+
C2+ 1
GND 2
27 V+
3
26 VCC
V- 4
25 C1-
C2-
T1OUT
5
24 T1IN
T2OUT
6
23 T2IN
T3OUT
7
22 T3IN
R1IN
8
21 R1OUT
R2IN
9
20 R2OUT
19 T4IN
T4OUT 10
18 R3OUT
R3IN 11
17 T5IN
T5OUT 12
1.4
EN 13
16 R1OUTB
SHDN 14
15 MBAUD
Pin Descriptions
Pin
Function
VCC
System power supply input (3.0V to 5.5V).
V+
Internally generated positive transmitter supply (+5.5V).
V-
Internally generated negative transmitter supply (-5.5V).
GND
Ground connection.
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 7).
TOUT
RIN
15kV ESD protected, RS-232 level (nominally ±5.5V) transmitter outputs.
15kV ESD protected, RS-232 compatible receiver inputs.
ROUT
TTL/CMOS level receiver outputs.
ROUTB
TTL/CMOS level, noninverting, always enabled receiver output.
FN6014 Rev.3.00
Apr.26.19
Page 4 of 21
ICL3237E
1. Overview
Pin
EN
SHDN
MBAUD
Function
Active low receiver enable control; doesn’t disable ROUTB output (Note 7).
Active low input to shut down transmitters and on-board power supply, to place device in low power mode (Note 7).
Input low selects the 250kbps data rate. Input high selects the 1Mbps data rate (Note 7).
Note:
7. These input pins incorporate positive feedback resistors. When the input is driven to a valid logic level, the feedback resistor maintains
that logic level until VCC is removed.
FN6014 Rev.3.00
Apr.26.19
Page 5 of 21
ICL3237E
2.
2. Specifications
Specifications
2.1
Absolute Maximum Ratings
Minimum
Maximum
Unit
VCC to GND
Parameter
-0.3
+6
V
V+ to GND
-0.3
+7
V
V- to GND
+0.3
-7
V
+14
V
+6
V
±25
V
±13.2
V
VCC + 0.3
V
V+ to VInput Voltages
TIN, EN, SHDN, MBAUD
-0.3
RIN
Output Voltages
TOUT
-0.3
ROUT
Short-Circuit Duration
Continuous
TOUT
See “ESD Rating” on page 6
ESD Rating
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions can adversely
impact product reliability and result in failures not covered by warranty.
2.2
Thermal Information
Thermal Resistance (Typical) (Note 8)
θJA (°C/W)
28 Ld SSOP Package
100
Note:
8. θJA is measured with the component mounted on a low-effective thermal conductivity test board in free air. See TB379 for details.
Parameter
Minimum
Maximum
+150
°C
-65
+150
°C
Maximum Junction Temperature (Plastic Package)
Maximum Storage Temperature Range
Pb-Free Reflow Profile
2.3
Unit
see TB493
Recommended Operating Conditions
Parameter
Minimum
Maximum
Unit
ICL3237ECx
0
+70
°C
ICL3237EIx
-40
+85
°C
Temperature Range
2.4
Electrical Specifications
Test Conditions: VCC = 3.15V to 5.5V, C1 - C4 = 0.1µF; VCC = 3V, C1 - C4 = 0.22µF, unless otherwisespecified. Typicals are at TA = 25oC
Parameter
Test Conditions
Temp (°C)
Min
Typ
Max
Unit
DC Characteristics
Supply Current,
Powerdown Disabled
All Outputs Unloaded, VCC = 3.15V, SHDN = VCC
25
-
0.3
1.0
mA
Supply Current,
Powerdown
SHDN = GND
25
-
10
300
nA
FN6014 Rev.3.00
Apr.26.19
Page 6 of 21
ICL3237E
2. Specifications
Test Conditions: VCC = 3.15V to 5.5V, C1 - C4 = 0.1µF; VCC = 3V, C1 - C4 = 0.22µF, unless otherwisespecified. Typicals are at TA = 25oC
Parameter
Test Conditions
Temp (°C)
Min
Typ
Max
Unit
Logic and Transmitter Inputs and Receiver Outputs
Input Logic Threshold
Low
TIN, EN, SHDN, MBAUD
Full
-
-
0.8
V
Input Logic Threshold
High
TIN, EN, SHDN,
MBAUD
VCC = 3.3V
Full
2.0
-
-
V
VCC = 5.0V
Full
2.4
-
-
V
25
-
0.5
-
V
Transmitter Input
Hysteresis
Input Leakage Current
TIN, EN, SHDN, MBAUD (Note 10)
Full
-
±0.01
±1.0
µA
Output Leakage
Current
EN = VCC (Receivers Disabled)
Full
-
±0.05
±10
µA
Output Voltage Low
IOUT = 1.6mA
Full
-
-
0.4
V
Output Voltage High
IOUT = -1.0mA
Full
-
V
VCC -0.6 VCC -0.1
Receiver Inputs
Input Voltage Range
Full
-25
-
25
V
VCC = 3.3V
25
0.6
1.2
-
V
VCC = 5.0V
25
0.8
1.5
-
V
VCC = 3.3V to 5.0V
25
-
1.6
2.4
V
Input Hysteresis
25
-
0.5
-
V
Input Resistance
25
3
5
7
kΩ
Input Threshold Low
Input Threshold High
Transmitter Outputs
Output Voltage Swing
All Transmitter Outputs Loaded with 3kΩ to Ground
Full
±5.0
±5.4
-
V
Output Resistance
VCC = V+ = V- = 0V, Transmitter Output = ±2V
Full
300
10M
-
Ω
Full
-
±35
±60
mA
VOUT = 12V, VCC = 0V or 3V to 5.5V, SHDN = GND
Full
-
-
±25
A
RL = 3kΩOne
CL = 1000pF
Transmitter Switching
VCC = 3V to 4.5V,
CL = 250pF
MBAUD = GND
Full
250
700
-
kbps
MBAUD = VCC
Full
1000
1700
-
kbps
MBAUD = VCC
Full
1000
1100
-
kbps
tPHL
25
-
0.15
-
µs
tPLH
25
-
0.15
-
µs
Output Short-Circuit
Current
Output Leakage
Current
Timing Characteristics
Maximum Data Rate
VCC = 4.5V to 5.5V,
CL = 1000pF
Receiver Propagation
Delay
Receiver Input to
Receiver Output,
CL = 150pF
Receiver Output
Enable Time
Normal Operation
25
-
200
-
ns
Receiver Output
Disable Time
Normal Operation
25
-
200
-
ns
Transmitter Skew
tPHL - tPLH, Note 9
MBAUD = GND
25
-
100
ns
MBAUD = VCC, VCC = 3.0V
25
-
25
ns
Receiver Skew
tPHL - tPLH, CL = 150pF
25
-
50
-
ns
Transition Region
Slew Rate
CL = 150pF to 1000pF MBAUD = GND
VCC = 3.3V,
RL = 3kΩto 7kΩ
MBAUD = VCC
Measured From 3V to
-3V or -3V to 3V
CL = 150pF to 2500pF MBAUD = GND
25
6
17
30
V/µs
25
24
40
150
V/µs
25
4
12
30
V/µs
FN6014 Rev.3.00
Apr.26.19
Page 7 of 21
ICL3237E
2. Specifications
Test Conditions: VCC = 3.15V to 5.5V, C1 - C4 = 0.1µF; VCC = 3V, C1 - C4 = 0.22µF, unless otherwisespecified. Typicals are at TA = 25oC
Parameter
Test Conditions
Temp (°C)
Min
Typ
Max
Unit
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
-
±2.5
-
kV
ESD Performance
RS-232 Pins (TOUT,
RIN)
All Other Pins
Notes:
9. Skew is measured at the input switching points (1.4V).
10. These inputs use a positive feedback resistor. The input current is negligible when the input is at either supply rail.
FN6014 Rev.3.00
Apr.26.19
Page 8 of 21
ICL3237E
3.
3. Typical Performance Curves
Typical Performance Curves
6
6
VOUT+
Transmitter Output Voltage (V)
Transmitter Output Voltage (V)
VOUT+
4
2
1 Transmitter at 250kbps
Other Transmitters at 30kbps
0
MBAUD = GND
-2
VOUT -
-4
-6
0
1000
2000
3000
4000
4
2
0
MBAUD = VCC
-2
VOUT -4
-6
5000
1 Transmitter at 1Mbps
Other Transmitters at 30kbps
0
1000
Load Capacitance (pF)
2000
3000
4000
Figure 1. Low Speed Transmitter Output Voltage vs
Load Capacitance
Figure 2. High Speed Transmitter Output Voltage vs
Load Capacitance
25
90
MBAUD = GND
MBAUD = VCC
70
20
+Slew
Slew Rate (V/µs)
Slew Rate (V/µs)
5000
Load Capacitance (pF)
15
-Slew
10
+Slew
50
30
-Slew
-Slew
10
5
0
1000
2000
3000
4000
0
5000
0
1000
Load Capacitance (pF)
Figure 3. Low Speed Slew Rate vs Load Capacitance
3000
4000
5000
Figure 4. High Speed Slew Rate vs Load Capacitance
90
55
MBAUD = VCC
MBAUD = GND
1Mbps
80
45
Supply Current (mA)
50
Supply Current (mA)
2000
Load Capacitance (pF)
250kbps
40
120kbps
35
30
25
70
60
50
250kbps
40
120kbps
30
20kbps
20
20
0
1000
2000
3000
4000
Load Capacitance (pF)
Figure 5. Low Speed Supply Current vs Load
Capacitance When Transmitting Data
FN6014 Rev.3.00
Apr.26.19
5000
0
1000
2000
3000
4000
5000
Load Capacitance (pF)
Figure 6. High Speed Supply Current vs Load
Capacitance When Transmitting Data
Page 9 of 21
ICL3237E
3. Typical Performance Curves
3.5
No Load
All Outputs Static
3.0
Supply Current (mA)
2.5
2.0
1.5
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 7. Supply Current vs Supply Voltage
FN6014 Rev.3.00
Apr.26.19
Page 10 of 21
ICL3237E
4.
4. Detailed Description
Detailed Description
The ICL3237E operates from a single +3V to +5.5V supply, ensures a 1Mbps minimum data rate (MBAUD = VCC),
requires only four small external 0.1µF (0.22µF for VCC = 3.0V) capacitors, features low power consumption, and
meets all EIA/TIA-232 and V.28 specifications.
4.1
Charge Pump
The ICL32xx family uses regulated on-chip dual charge pumps as voltage doublers. It uses voltage inverters to
generate ±5.5V transmitter supplies from a VCC supply as low as 3.0V. The charge pumps allow 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 at VCC = 3.3V. See the “Capacitor Selection” on page 13 and Table 6 on page 13 for capacitor
recommendations for other operating conditions. The charge pumps operate discontinuously (turning off as soon
as the V+ and V- supplies are pumped up to the nominal values) and provide significant power savings.
4.1.1 Charge Pump Abs Max Ratings
The ICL3237E is fully characterized for 3.0V to 3.6V operation, and at critical points for 4.5V to 5.5V operation.
Furthermore, load conditions were favorable using static logic states only.
The specified maximum values for V+ and V- are +7V and -7V, respectively. These limits apply for VCC values set
to 3.0V and 3.6V (see Table 2). For VCC values set to 4.5V and 5.5V, the maximum values for V+ and V- can
approach +9V and -7V, respectively (Table 3 on page 12). The breakdown characteristics for V+ and V- were
measured with ±13V.
Table 2.
V+ and V- Values for VCC = 3.0V to 3.6V
C1 (μF)
C2, C3, C4 (μF)
Load
T1IN
(Logic State)
0.1
0.1
Open
H
3kΩ // 1000pF
0.047
0.33
Open
3kΩ // 1000pF
1
1
Open
3kΩ // 1000pF
FN6014 Rev.3.00
Apr.26.19
V+ (V)
V- (V)
VCC = 3.0V
VCC = 3.6V
VCC = 3.0V
VCC = 3.6V
5.80
6.56
-5.60
-5.88
L
5.80
6.56
-5.60
-5.88
2.4kbps
5.80
6.56
-5.60
-5.88
H
5.88
6.60
-5.56
-5.92
L
5.76
6.36
-5.56
-5.76
2.4kbps
6.00
6.64
-5.64
-5.96
H
5.68
6.00
-5.60
-5.60
L
5.68
6.00
-5.60
-5.60
2.4kbps
5.68
6.00
-5.60
-5.60
H
5.76
6.08
-5.64
-5.64
L
5.68
6.04
-5.60
-5.60
2.4kbps
5.84
6.16
-5.64
-5.72
H
5.88
6.24
-5.60
-5.60
L
5.88
6.28
-5.60
-5.64
2.4kbps
5.80
6.20
-5.60
-5.60
H
5.88
6.44
-5.64
-5.72
L
5.88
6.04
-5.64
-5.64
2.4kbps
5.92
6.40
-5.64
-5.64
Page 11 of 21
ICL3237E
Table 3.
4. Detailed Description
V+ and V- Values for VCC = 4.5V to 5.5V
V+ (V)
V- (V)
C1 (μF)
C2, C3, C4 (μF)
Load
T1IN
(Logic State)
0.1
0.1
Open
H
7.44
8.48
-6.16
-6.40
L
7.44
8.48
-6.16
-6.44
2.4kbps
7.44
8.48
-6.17
-6.44
H
7.76
8.88
-6.36
-6.72
3kΩ // 1000pF
0.047
0.33
Open
3kΩ // 1000pF
1
1
Open
3kΩ // 1000pF
VCC = 4.5V
VCC = 5.5V
VCC = 4.5V
VCC = 5.5V
L
7.08
8.00
-5.76
-5.76
2.4kbps
7.76
8.84
-6.40
-6.64
H
6.44
6.88
-5.80
-5.88
L
6.48
6.88
-5.84
-5.88
2.4kbps
6.44
6.88
-5.80
-5.88
H
6.64
7.28
-5.92
-6.04
L
6.24
6.60
-5.52
-5.52
2.4kbps
6.72
7.16
-5.92
-5.96
H
6.84
7.60
-5.76
-5.76
L
6.88
7.60
-5.76
-5.76
2.4kbps
6.92
7.56
-5.72
-5.76
H
7.28
8.16
-5.80
-5.92
L
6.44
6.84
-5.64
-6.84
2.4kbps
7.08
7.76
-5.80
-5.80
The resulting new maximum voltages at V+ and V- are listed in Table 4.
Table 4.
4.2
New Measured Withstanding Voltages
V+, V- to Ground
±13V
V+ to V-
20V
Transmitters
The transmitters are proprietary, low dropout, inverting drivers that translate TTL/CMOS inputs to EIA/TIA-232
output levels. The transmitters are coupled with the on-chip ±5.5V supplies tp deliver true RS-232 levels across a
wide range of single supply system voltages.
All transmitter outputs disable and assume a high impedance state when the device enters the powerdown mode
(see Table 5 on page 13). These outputs can be driven to ±12V when disabled.
The ICL3237E ensures a 1Mbps data rate (MBAUD = VCC) for full load conditions (3kΩ and 250pF), VCC ≥ 3.0V,
with one transmitter operating at full speed. Under more typical conditions of VCC ≥ 3.3V, C1-4 = 0.1µF, RL = 3kΩ,
and CL = 250pF, one transmitter easily operates at 1.7Mbps.
Transmitter inputs incorporate an active positive feedback resistor that maintains the last driven input state in the
absence of a forcing signal. Unused transmitter inputs can remain unconnected.
4.3
Receivers
The ICL3237E contains standard inverting receivers that tri-state only when the EN control line is driven high. It
also includes a noninverting (monitor) receiver (denoted by the ROUTB label) that is 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 3kΩ to 7kΩ input impedance (see Figure 8 on page 13) 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.
FN6014 Rev.3.00
Apr.26.19
Page 12 of 21
ICL3237E
4. Detailed Description
Monitor receivers remain active even during manual powerdown and forced receiver disable, which makes 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 9 and 10). Disabling the
receivers prevents them from being used for wake up functions, but the corresponding monitor receiver can be
dedicated to this task as shown in Figure 10.
VCC
RXIN
RXOUT
-25V ≤ VRIN ≤ +25V
5kΩ
GND ≤ VROUT ≤ VCC
GND
Figure 8. Inverting Receiver Connections
4.4
Operation Down to 2.7V
ICL3237E 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.
4.5
Powerdown Functionality
The ICL3237E requires a nominal supply current of 0.3mA during normal operation (not in powerdown mode).
This supply current is considerably less than the 5mA to 11mA current required of 5V RS-232 devices. The
already low current requirement drops significantly when the device enters powerdown mode. In powerdown,
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 tri-state. This micro-power mode makes the ICL3237E ideal for battery
powered and portable applications.
4.5.1 Software Controlled (Manual) Powerdown
On the ICL3237E, the powerdown control is a simple shutdown pin (SHDN). Driving SHDN high enables normal
operation, and driving it low forces the IC into its powerdown state. Connect SHDN to VCC if the powerdown
function is not needed. Note: All the receiver outputs remain enabled during shutdown (see Table 5). For the
lowest power consumption during powerdown, disable the receivers by driving the EN input high (see “Receiver
ENABLE Control” on page 14 and Figures 9 and 10). The time required to exit powerdown and resume
transmission is 100µs.
Table 5.
Powerdown and Enable Logic Truth Table
SHDN Input
EN Input
Transmitter Outputs
Receiver Outputs
ROUTB Output
L
L
High-Z
Active
Active
Manual Powerdown
L
H
High-Z
High-Z
Active
Manual Powerdown w/Rcvr. Disabled
H
L
Active
Active
Active
Normal Operation
H
H
Active
High-Z
Active
Normal Operation w/Rcvr. Disabled
4.6
Mode of Operation
Capacitor Selection
The charge pumps require 0.1µF capacitors for 3.3V (5% tolerance) operation. For other supply voltages, see
Table 6 for capacitor values. Do not use values smaller than those listed in Table 6. Increasing the capacitor
values (by a factor of 2) reduces ripple on the transmitter outputs and 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).
Table 6.
Required Capacitor Values
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
FN6014 Rev.3.00
Apr.26.19
Page 13 of 21
ICL3237E
Table 6.
4. Detailed Description
Required Capacitor Values (Continued)
VCC (V)
C1 (µF)
C2, C3, C4 (µF)
4.5 to 5.5
0.047
0.33
3.0 to 5.5
0.22
1.0
VCC
VCC
Current
Flow
VCC
VOUT = VCC
Rx
Powered
Down
UART
Tx
SHDN = GND
GND
Old
RS-232 Chip
Figure 9. Power Drain Through Powered Down Peripheral
VCC
Transition
Detector
To
Wake-Up
Logic
ICL3237E
VCC
R1OUTB
RX
Powered
Down
UART
VOUT = HI-Z
R1OUT
TX
R1IN
T1IN
T1OUT
SHDN = GND, EN = VCC
Figure 10. Disabled Receivers Prevent Power Drain
4.7
Receiver ENABLE Control
The ICL3237E features an EN input to control the receiver outputs. Driving EN high disables all the inverting
(standard) receiver outputs and places them in a high impedance state. Disabling the receiver outputs is useful to
eliminate supply current, due to a receiver output forward biasing the protection diode when driving the input of a
powered down (VCC = GND) peripheral (see Figure 9). The enable input has no effect on transmitter or monitor
(ROUTB) outputs.
FN6014 Rev.3.00
Apr.26.19
Page 14 of 21
ICL3237E
4.8
4. Detailed Description
MegaBaud Selection
In normal operating mode (MBAUD = GND), the ICL3237E transmitters ensure a 250kbps data rate with
worst-case loads of 3kΩ in parallel with 1000pF. This data rate provides compatibility with PC-to-PC
communication software such as Laplink.
For higher speed serial communications, the ICL3237E features MegaBaud operation. In MegaBaud operating
mode (MBAUD = VCC), the ICL3237E transmitters ensure a 1Mbps data rate with worst-case loads of 3kΩ in
parallel with 250pF for 3.0V < VCC < 4.5V. For 5V ±10% operation, the ICL3237E transmitters ensure a 1Mbps
data rate with worst-case loads of 3kΩ in parallel with 1000pF.
4.9
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.
4.10
Transmitter Outputs when Exiting Powerdown
Figure 11 shows the response of two transmitter outputs when exiting powerdown mode. As the two transmitter
outputs activate, they properly go to opposite RS-232 levels with no glitching, ringing, or undesirable transients.
Each transmitter is loaded with 3kΩin parallel with 2500pF. Note: The transmitters enable only when the
magnitude of the supplies exceed approximately 3V.
5V/Div
SHDN
T1
2V/Div
T2
VCC = +3.3V
C1 - C4 = 0.1µF
Time (20µs/Div)
Figure 11. Transmitter Outputs When Exiting Powerdown
FN6014 Rev.3.00
Apr.26.19
Page 15 of 21
ICL3237E
4.11
4. Detailed Description
High Data Rates
The ICL3237E maintains the RS-232 ±5V minimum transmitter output voltages even at high data rates. Figure 12
shows a transmitter loopback test circuit and Figure 13 shows the standard speed loopback test result for a single
transmitter driving 1000pF and an RS-232 load at 250kbps. Figure 14 shows the MegaBaud 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.
VCC
+
0.1µF
+
VCC
C1+
C1
V+
+
C3
C1ICL3237E
+
V-
C2+
C2
C4
+
C2TIN
TOUT
EN
VCC
CL
RIN
ROUT
5k
SHDN
GND or VCC
MBAUD
Figure 12. Transmitter Loopback Test Circuit
5V/Div MBAUD = VCC
5V/Div MBAUD = GND
T1IN
T1IN
T1OUT
T1OUT
R1OUT
R1OUT
VCC = +3.3V
C1 - C4 = 0.1µF
VCC = +3.3V
C1 - C4 = 0.1µF
0.5µs/Div
2µs/Div
Figure 14. Loopback Test at 1Mbps (CL = 250pF)
Figure 13. Loopback Test at 250kbps (CL = 1000pF)
4.12
Interconnection with 3V and 5V Logic
The ICL3237E directly interfaces with 5V CMOS and TTL logic families. AC, HC, and CD4000 outputs can drive
the ICL32xx inputs with the ICL32xx at 3.3V and the logic supply at 5V, but ICL32xx outputs do not reach the
minimum VIH for these logic families. See Table 7 for more information.
Table 7.
Logic Family Compatibility With Various Supply Voltages
System Power-Supply Voltage (V)
VCC Supply Voltage (V)
3.3
3.3
5
5
5
3.3
FN6014 Rev.3.00
Apr.26.19
Compatibility
Compatible with all CMOS families.
Compatible with all TTL and CMOS logic families.
Compatible with ACT and HCT CMOS, and with TTL. ICL32xx outputs
are incompatible with AC, HC, and CD4000 CMOS inputs.
Page 16 of 21
ICL3237E
5.
5. ±15kV ESD Protection
±15kV ESD Protection
All pins on the ICL32xx devices include ESD protection structures, but the ICL32xxE family incorporates
advanced structures that allow the RS-232 pins (transmitter outputs and receiver inputs) 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. Touching the port pins or connecting a cable can cause an
ESD event that might destroy unprotected ICs. The ESD structures protect the device whether or not it is powered
up, protect without allowing any latchup mechanism to activate, and do not interfere with RS-232 signals as large
as ±25V.
5.1
Human Body Model (HBM) Testing
The Human Body Model (HBM) 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, so the test is less severe than the
IEC61000 test, which uses a 330Ω limiting resistor. The HBM method determines an IC’s 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.
5.2
IEC61000-4-2 Testing
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.
5.3
Air-Gap Discharge Test Method
For the air-gap discharge 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 factors such as approach speed, humidity, and
temperature, so it is difficult to obtain repeatable results.The “E” device RS-232 pins withstand ±15kV air-gap
discharges.
5.4
Contact Discharge Test Method
During the contact discharge test, the probe contacts the tested pin before the probe tip is energized and
eliminates 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.
FN6014 Rev.3.00
Apr.26.19
Page 17 of 21
ICL3237E
6.
6. Die Characteristics
Die Characteristics
Substrate Potential (Powered Up)
GND
Transistor Count
619
Process
Si Gate CMOS
FN6014 Rev.3.00
Apr.26.19
Page 18 of 21
ICL3237E
7.
7. Revision History
Revision History
Rev.
Date
6.00
Apr.26.19
FN6014 Rev.3.00
Apr.26.19
Description
Added Related Literature section
Updated ordering information table:
- Added tape and reel information and notes 4-6
- Removed ICL3237ECA and ICL3237EIA
- Added ICL3237ECAZ-T and ICL3237EIAZ-T
Added Charge Pump Abs Max Ratings section starting on page 11.
Updated package outline drawing from revision 1 to revision 2.
- Removed "u" symbol from drawing (overlaps the "a" on Side View).
Applied new template.
Page 19 of 21
ICL3237E
8.
8. Package Outline Drawing
Package Outline Drawing
For the most recent package outline drawing, see M28.209.
M28.209 (JEDEC MO-150-AH ISSUE B)
28 Lead Shrink Small Outline Plastic Package (SSOP)
N
INCHES
INDEX
AREA
H
0.25(0.010) M
E
GAUGE
PLANE
-B1
2
3
0.25
0.010
SEATING PLANE
-A-
SYMBOL
B M
A
D
e
A2
A1
B
C
0.10(0.004)
C A M
B S
Notes:
1. Symbols are defined in the “MO Series Symbol List” in Section 2.2
of Publication Number 95.
MAX
MIN
MAX
NOTES
A
-
0.078
-
2.00
-
A1
0.002
-
0.05
-
-
A2
0.065
0.072
1.65
1.85
-
B
0.009
0.014
0.22
0.38
9
C
0.004
0.009
0.09
0.25
-
D
0.390
0.413
9.90
10.50
3
E
0.197
0.220
5.00
5.60
4
e
-C-
0.25(0.010) M
L
MILLIMETERS
MIN
0.026 BSC
0.65 BSC
-
H
0.292
0.322
7.40
8.20
-
L
0.022
0.037
0.55
0.95
6
8°
0°
N
28
0°
28
7
8°
Rev. 2 6/05
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension “D” does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed
0.20mm (0.0078 inch) per side.
4. Dimension “E” does not include interlead flash or protrusions.
Interlead flash and protrusions shall not exceed 0.20mm (0.0078
inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.
6. “L” is the length of terminal for soldering to a substrate.
7. “N” is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. Dimension “B” does not include dambar protrusion. Allowable
dambar protrusion shall be 0.13mm (0.005 inch) total in excess of
“B” dimension at maximum material condition.
10. Controlling dimension: MILLIMETER. Converted inch dimensions
are not necessarily exact.
FN6014 Rev.3.00
Apr.26.19
Page 20 of 21
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