FN4900 Rev.13.00 Page 1 of 28
May.2.19
ICL3225E, ICL3227E, ICL3245E
±15kV ESD Protected, +3V to +5.5V, 1µA, 1Mbps, RS-232 Transceivers with
Enhanced Automatic Powerdown
Datasheet
The ICL3225E, ICL3227E, and ICL3245E devices are
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. 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 power consumption and even
lower standby power consumption are critical.
Efficient on-chip charge pumps coupled with manual
and enhanced automatic powerdown functions,
reduce the standby supply current to a 1µA trickle.
Small footprint packaging and the use of small, low
value capacitors ensure board space savings. Data
rates greater than 1Mbps are ensured at worst case
load conditions. This family is fully compatible with
3.3V only systems, mixed 3.3V and 5.0V systems,
and 5.0V only systems.
The ICL3245E is a 3-driver, 5-receiver device that
provides a complete serial port suitable for laptop or
notebook computers. It also includes a noninverting
always-active receiver for “wake-up” capability.
The ICL3225E, ICL3227E, and ICL3245E feature an
enhanced automatic powerdown function that powers
down the on-chip power supply and driver circuits.
Powerdown 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 device
represented by this datasheet and AN9863
summarizes the features of each device in the
ICL32xxE 3V family.
Related Literature
For a full list of related documents, visit our website:
ICL3225E, ICL3227E, and ICL3245E device pages
Features
Pb-free (RoHS compliant)
ESD protection for RS-232 I/O pins to ±15kV
(IEC61000)
Manual and enhanced automatic powerdown
features
Drop in replacements for MAX3225E, MAX3227E,
MAX3245E
RS-232 compatible with VCC = 2.7V
Meets EIA/TIA-232 and V.28/V.24 specifications at
3V
Latch-up free
On-chip voltage converters require only four
external 0.1µF capacitors
Ensured mouse driveability (ICL3245E)
“Ready to Transmit” indicator output
(ICL3225E/ICL3227E)
Receiver hysteresis for improved noise immunity
Ensured minimum data rate: 1Mbps
Low skew at transmitter/receiver input trip
points: 10ns
Ensured minimum slew rate: 24V/µs
Wide power supply range: single +3V to +5.5V
Low supply current in powerdown state: 1µA
Applications
Any system requiring RS-232 communication ports
Battery powered, hand-held, and portable
equipment
Laptop computers, notebooks, palmtops
Modems, printers, and other peripherals
Digital cameras
Cellular/mobile phones
ICL3225E, ICL3227E, ICL3245E
FN4900 Rev.13.00 Page 2 of 28
May.2.19
Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Typical Operating Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Thermal Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Typical Performance Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Application Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1 Charge Pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1.1 Charge Pump Abs Max Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Receivers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.4 Powerdown Functionality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.4.1 Software Controlled (Manual) Powerdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.4.2 INVALID Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.4.3 Enhanced Automatic Powerdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.4.4 Emulating Standard Automatic Powerdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.4.5 Hybrid Automatic Powerdown Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.5 READY Output (ICL3225E and ICL3227E Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.6 Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.7 Power Supply Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.8 Operation Down to 2.7V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.9 Transmitter Outputs when Exiting Powerdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.10 Mouse Driveability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.11 High Data Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.12 Interconnection with 3V and 5V Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5. ±15kV ESD Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.1 Human Body Model (HBM) Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 IEC61000-4-2 Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3 Air-Gap Discharge Test Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.4 Contact Discharge Test Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6. Die Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7. Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8. Package Outline Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
ICL3225E, ICL3227E, ICL3245E 1. Overview
FN4900 Rev.13.00 Page 3 of 28
May.2.19
1. Overview
1.1 Typical Operating Circuits
Figure 1. ICL3225E
Figure 2. ICL3227E
19
VCC
T1OUT
T2OUT
T1IN
T2IN
T1
T2
0.1µF
+0.1µF
+
0.1µF
13
12
17
8
2
4
3
7
V+
V-
C1+
C1-
C2+
C2-
+
0.1µF
5
6
R1OUT R1IN
16
5kΩ
R2OUT R2IN
910
5kΩ
15
C1
C2
+C3
C4
READY
1
GND
+3.3V +0.1µF
18
TTL/CMOS
Logic Levels
RS-232
Levels
R1
R2
FORCEON
FORCEOFF
14
20 VCC
11
INVALID To Power
Control Logic
15
VCC
T1OUT
T1IN
T1
0.1µF
+0.1µF
+
0.1µF
11 13
2
4
3
7
V+
V-
C1+
C1-
C2+
C2-
+
0.1µF
5
6
R1OUT R1IN
R1
89
5kΩ
C1
C2
+C3
C4
READY
1
GND
+3.3V +0.1µF
14
TTL/CMOS
Logic Levels
RS-232
Levels
FORCEON
FORCEOFF
12
16 VCC
10
INVALID To Power
Control Logic
ICL3225E, ICL3227E, ICL3245E 1. Overview
FN4900 Rev.13.00 Page 4 of 28
May.2.19
Figure 3. ICL3245E
26
VCC
T1OUT
T2OUT
T3OUT
T1IN
T2IN
T3IN
T1
T2
T3
0.1µF
+
0.1µF
+
0.1µF
14
13
9
10
12 11
28
24
27
3
V+
V-
C1+
C1-
C2+
C2-
+
0.1µF
1
2
R1OUT R1IN
4
5kΩ
R2OUT R2IN
518
5kΩ
R3OUT R3IN
617
5kΩ
R4OUT R4IN
716
5kΩ
R5OUT R5IN
R5
815
5kΩ
19
R2OUTB
C1
C2
+C3
C4
FORCEON
FORCEOFF
23
GND
22
+3.3V +0.1µF
20
25
VCC
TTL/CMOS
Logic Levels
RS-232
Levels
RS-232
Levels
R1
R2
R3
R4
21
INVALID
To Power
Control Logic
ICL3225E, ICL3227E, ICL3245E 1. Overview
FN4900 Rev.13.00 Page 5 of 28
May.2.19
1.2 Ordering Information
1.3 Pin Configurations
Part Number
(Notes 2, 3) Part Marking Temp Range (°C)
Tape and Reel
(Units) (Note 1)
Package
(RoHS Compliant) Pkg. Dwg. #
ICL3225ECAZ ICL3225ECAZ 0 to +70 - 20 Ld SSOP M20.209
ICL3225ECAZ-T ICL3225ECAZ 0 to +70 1k 20 Ld SSOP M20.209
ICL3225EIAZ ICL3225EIAZ -40 to +85 - 20 Ld SSOP M20.209
ICL3225EIAZ-T ICL3225EIAZ -40 to +85 1k 20 Ld SSOP M20.209
ICL3227ECAZA 3227ECAZ 0 to +70 - 16 Ld SSOP M16.209
ICL3227ECAZA-T 3227ECAZ 0 to +70 1k 16 Ld SSOP M16.209
ICL3227EIAZA 3227EIAZ -40 to +85 - 16 Ld SSOP M16.209
ICL3227EIAZA-T 3227EIAZ -40 to +85 1k 16 Ld SSOP M16.209
ICL3245ECAZ ICL3245ECAZ 0 to +70 - 28 Ld SSOP M28.209
ICL3245ECAZ-T ICL3245ECAZ 0 to +70 1k 28 Ld SSOP M28.209
ICL3245EIAZ ICL3245EIAZ -40 to +85 - 28 Ld SSOP M28.209
ICL3245EIAZ-T ICL3245EIAZ -40 to +85 1k 28 Ld SSOP M28.209
Notes:
1. See TB347 for details about reel specifications.
2. These 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).
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.
3. For Moisture Sensitivity Level (MSL), see the ICL3225E, ICL3227E, and ICL3245E device pages. For more information about MSL, see
TB363.
Table 1. Summary of Features
Part Number
Number
of Tx.
Number
of Rx.
Number of
Monitor Rx.
(ROUTB)
Data Rate
(kbps)
Rx. Enable
Function?
Ready
Output?
Manual
Powerdown?
Enhanced
Automatic
Powerdown
Function?
ICL3225E 2 2 0 1000 No Yes Yes Yes
ICL3227E 1 1 0 1000 No Yes Yes Yes
ICL3245E 3 5 1 1000 No No Yes Yes
ICL3225E (SSOP)
Top View
ICL3227E (SSOP)
Top View
READY
C1+
V+
C1-
C2+
C2-
V-
T2OUT
R2IN
FORCEOFF
GND
T1OUT
R1IN
R1OUT
T1IN
INVALID
VCC
FORCEON
T2IN
20
19
18
17
16
15
14
13
12
11
1
2
3
4
5
6
7
8
9
10
R2OUT
READY
C1+
V+
C1-
C2+
C2-
V-
R1IN
FORCEOFF
GND
T1OUT
FORCEON
T1IN
R1OUT
VCC
INVALID
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
ICL3225E, ICL3227E, ICL3245E 1. Overview
FN4900 Rev.13.00 Page 6 of 28
May.2.19
1.4 Pin Descriptions
ICL3245E (SSOP)
Top View
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.
TxIN TTL/CMOS compatible transmitter Inputs.
TxOUT ±15kV ESD protected, RS-232 level (nominally ±5.5V) transmitter outputs.
RxIN ±15kV ESD protected, RS-232 compatible receiver inputs.
RxOUT TTL/CMOS level receiver outputs.
R2OUTB 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.
READY Active high output that indicates when the ICL32xxE is ready to transmit (V- ≤ -4V).
FORCEOFF Active low to shut down transmitters and on-chip power supply, which overrides any automatic circuitry and FORCEON (see
Table 5 on page 15).
FORCEON Active high input to override automatic powerdown circuitry and keeps transmitters active. (FORCEOFF must be high).
C2+
C2-
V-
R1IN
R2IN
R3IN
R4IN
R5IN
T1OUT
T3OUT
T3IN
T2IN
T1IN
C1+
VCC
GND
C1-
FORCEON
INVALID
R1OUT
R2OUT
R3OUT
R4OUT
R5OUT
V+
FORCEOFF
R2OUTB
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
T2OUT
ICL3225E, ICL3227E, ICL3245E 2. Specifications
FN4900 Rev.13.00 Page 7 of 28
May.2.19
2. Specifications
2.1 Absolute Maximum Ratings
2.2 Thermal Information
2.3 Recommended Operating Conditions
Parameter Minimum Maximum Unit
VCC to GND -0.3 6 V
V+ to GND -0.3 7 V
V- to GND +0.3 -7 V
V+ to V- 14 V
Input Voltages
TIN, FORCEOFF, FORCEON -0.3 6 V
RIN ±25 V
Output Voltages
TOUT ±13.2 V
ROUT
, INVALID, READY -0.3 VCC +0.3 V
Short-Circuit Duration
TOUT Continuous
ESD Rating (See ESD Performance” on page 9)
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.
Thermal Resistance (Typical, Note 4
JA (°C/W)
16 Ld SSOP Package 145
20 Ld SSOP Package 135
28 Ld SSOP Package 100
Notes:
4. 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 Unit
Maximum Junction Temperature (Plastic Package) +150 °C
Maximum Storage Temperature Range -65 +150 °C
Pb-Free Reflow Profile see TB493
Parameter Minimum Maximum Unit
Temperature Range
ICL32xxEC 0 +70 °C
ICL32xxEI -40 +85 °C
ICL3225E, ICL3227E, ICL3245E 2. Specifications
FN4900 Rev.13.00 Page 8 of 28
May.2.19
2.4 Electrical Specifications
Test conditions: VCC = 3V to 5.5V, C1 - C4 = 0.1µF; unless otherwise specified. Typicals are at TA = +25°C
Parameter Test Conditions
Temp
(°C) Min Typ Max Unit
DC Characteristics
Supply Current, Automatic
Powerdown
All RIN open, FORCEON = GND, FORCEOFF = VCC +25 - 1.0 10 µA
Supply Current, Powerdown FORCEOFF = GND +25 - 1.0 10 µA
Supply Current,
Automatic Powerdown Disabled
All outputs unloaded, FORCEON = FORCEOFF = VCC +25 - 0.3 1.0 mA
Logic and Transmitter Inputs and Receiver Outputs
Input Logic Threshold Low TIN, FORCEON, FORCEOFF Full - - 0.8 V
Input Logic Threshold High TIN, FORCEON,
FORCEOFF
VCC = 3.3V Full 2.0 - - V
VCC = 5.0V Full 2.4 - - V
Input Leakage Current TIN, FORCEON, FORCEOFF Full - ±0.01 ±1.00 µA
Output Leakage Current FORCEOFF = GND, ICL3245E only Full - ±0.05 ±10 µA
Output Voltage Low IOUT = 1.6mA Full - - 0.4 V
Output Voltage High IOUT = -1.0mA Full VCC - 0.6 VCC - 0.1 - V
Receiver Inputs
Input Voltage Range Full -25 - 25 V
Input Threshold Low VCC = 3.3V +25 0.6 1.2 - V
VCC = 5.0V +25 0.8 1.5 - V
Input Threshold High VCC = 3.3V +25 - 1.5 2.4 V
VCC = 5.0V +25 - 1.8 2.4 V
Input Hysteresis +25 - 0.5 - V
Input Resistance +25 3 5 7
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
Output Short-Circuit Current Full - ±35 ±60 mA
Output Leakage Current VOUT = ±12V, VCC = 0V or 3V to 5.5V, automatic powerdown
or FORCEOFF = GND
Full - - ±25 µA
Mouse Driveability
Transmitter Output Voltage
(See Figure 20 on page 20)
T1IN = T2IN = GND, T3IN = VCC, T3OUT loaded with 3kΩ to
GND, T1OUT and T2OUT loaded with 2.5mA each
Full ±5 - - V
Enhanced Automatic Powerdown (FORCEON = GND, FORCEOFF = VCC)
Receiver Input Thresholds to
INVALID High
See Figure 15 on page 17 Full -2.7 - 2.7 V
Receiver Input Thresholds to
INVALID Low
See Figure 15 on page 17 Full -0.3 - 0.3 V
INVALID, READY Output Voltage
Low
IOUT = 1.6mA Full - - 0.4 V
INVALID, READY Output Voltage
High
IOUT = -1.0mA Full VCC - 0.6 - - V
Receiver Positive or Negative
Threshold to INVALID High Delay
(tINVH)
+25 - 1 - µs
ICL3225E, ICL3227E, ICL3245E 2. Specifications
FN4900 Rev.13.00 Page 9 of 28
May.2.19
Receiver Positive or Negative
Threshold to INVALID Low Delay
(tINVL)
+25 - 30 - µs
Receiver or Transmitter Edge to
Transmitters Enabled Delay (tWU)
(Note 5) 25 - 100 - µs
Receiver or Transmitter Edge to
Transmitters Disabled Delay
(tAUTOPWDN)
(Note 5) Full 15 30 60 sec
Timing Characteristics
Maximum Data Rate RL = 3kΩ, one transmitter
switching
CL = 1000pF Full 250 - - kbps
VCC = 3V to 4.5V, CL = 250pF Full 1000 - - kbps
VCC = 4.5V to 5.5V,
CL= 1000pF
Full 1000 - - kbps
Receiver Propagation Delay Receiver input to receiver
output, CL = 150pF
tPHL +25 - 0.15 - µs
tPLH +25 - 0.15 - µs
Receiver Output Enable Time Normal operation (ICL3245E only) +25 - 200 - ns
Receiver Output Disable Time Normal operation (ICL3245E only) +25 - 200 - ns
Transmitter Skew tPHL - tPLH (Note 6)+25-25-ns
Receiver Skew tPHL - tPLH (Note 6)+25-50-ns
Transition Region Slew Rate VCC = 3.3V, RL = 3kΩ to 7kΩ, measured from 3V to -3V or
-3V to 3V, CL = 150pF to 1000pF
+25 24 - 150 V/µs
ESD Performance
RS-232 Pins (TOUT
, RIN) Human body model +25 - ±15 - kV
IEC61000-4-2 contact discharge +25 - ±8 - kV
IEC61000-4-2 air gap discharge +25 - ±15 - kV
All Other Pins ICL3245E Human body model (HBM) +25 - ±2 - kV
Charged Device Model (CDM) +25 - ±1.5 - kV
ICL3225E, ICL3227E Human body model (HBM) +25 - ±4 - kV
Charged Device Model (CDM) +25 - ±2 - kV
Notes:
5. An “edge” is defined as a transition through the transmitter or receiver input thresholds.
6. Skews are measured at the receiver input switching points (1.4V).
Test conditions: VCC = 3V to 5.5V, C1 - C4 = 0.1µF; unless otherwise specified. Typicals are at TA = +25°C (Continued)
Parameter Test Conditions
Temp
(°C) Min Typ Max Unit
ICL3225E, ICL3227E, ICL3245E 3. Typical Performance Curves
FN4900 Rev.13.00 Page 10 of 28
May.2.19
3. Typical Performance Curves
VCC = 3.3V, TA = +25°C
Figure 4. Transmitter Output Voltage vs Load
Capacitance
Figure 5. Slew Rate vs Load Capacitance
Figure 6. Supply Current vs Load Capacitance When
Transmitting Data
Figure 7. Supply Current vs Load Capacitance When
Transmitting Data
-6
-4
-2
0
2
4
6
1000 2000 3000 4000 50000
Load Capacitance (pF)
Transmitter Output Voltage (V)
1 Transmitter at 1Mbps
VOUT+
VOUT-
Other Transmitters at 30kbps
Load Capacitance (pF)
Slew Rate (V/µs)
0 1000 2000 3000 4000 5000
0
10
30
50
110
-SLEW
+SLEW
70
90
01000 2000 3000 4000 5000
Load Capacitance (pF)
Supply Current (mA)
10
20
30
40
50
80
60
70
90
250kbps
120kbps
ICL3225E
1Mbps
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Supply Current (mA)
10
20
30
40
50
80
60
70
90
ICL3227E
250kbps
120kbps
1Mbps
ICL3225E, ICL3227E, ICL3245E 3. Typical Performance Curves
FN4900 Rev.13.00 Page 11 of 28
May.2.19
Figure 8. Supply Current vs Load Capacitance When
Transmitting Data
Figure 9. Supply Current vs Supply Voltage
VCC = 3.3V, TA = +25°C (Continued)
10
20
30
40
50
80
60
70
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
Supply Current (mA)
120kbps
1Mbps
250kbps
90
ICL3245E
Supply Current (mA)
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
0
0.5
1.0
1.5
2.0
Supply Voltage (V)
2.5
3.0
3.5
No Load
All Outputs Static
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 12 of 28
May.2.19
4. Application Information
The ICL3225E, ICL3227E, and ICL3245E (ISL32xxE) operate from a single +3V to +5.5V supply, ensure a 1Mbps
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.
4.1 Charge Pump
The ICL32xxE use 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, which 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 at
VCC = 3.3V. See the Capacitor Selection, and Table 6 on page 19 for capacitor recommendations for other
operating conditions. The charge pumps operate discontinuously (turning off when the V+ and V- supplies are
pumped up to the nominal values), resulting in significant power savings.
4.1.1 Charge Pump Abs Max Ratings
These 3V to 5V RS-232 transceivers have been fully characterized for 3.0V to 3.6V operation and for critical
points at 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 13). 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)
V+ (V) V- (V)
VCC = 3.0V VCC = 3.6V VCC = 3.0V VCC = 3.6V
0.1 0.1 Open H 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
3kΩ // 1000pF 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
0.047 0.33 Open 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
3kΩ // 1000pF 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
1 1 Open 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
3kΩ // 1000pF 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
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 13 of 28
May.2.19
The resulting new maximum voltages at V+ and V- are listed in Table 4.
4.2 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 to deliver true RS-232 levels over a
wide range of single supply system voltages.
Transmitter outputs disable and assume a high impedance state when the device enters the powerdown mode
(see Table 5 on page 15). The outputs can be driven to ±12V when disabled.
All devices ensure a 1Mbps data rate 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, RL= 3kΩ, and CL = 250pF, one transmitter
easily operates at 1.4Mbps. Transmitter skew is extremely low on these devices, and is specified at the receiver
input trip points (1.4V), rather than the arbitrary 0V crossing point typical of other RS-232 families.
Transmitter inputs float if they remain unconnected and can increase ICC. Connect unused inputs to GND for best
performance.
Table 3. V+ and V- Values for VCC = 4.5V to 5.5V
C1 (μF) C2, C3, C4 (μF) Load
T1IN
(Logic State)
V+ (V) V- (V)
VCC = 4.5V VCC = 5.5V VCC = 4.5V VCC = 5.5V
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
3kΩ // 1000pF H 7.76 8.88 -6.36 -6.72
L 7.08 8.00 -5.76 -5.76
2.4kbps 7.76 8.84 -6.40 -6.64
0.047 0.33 Open 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
3kΩ // 1000pF 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
1 1 Open 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
3kΩ // 1000pF 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
Table 4. New Measured Withstanding Voltages
V+, V- to Ground ±13V
V+ to V- 20V
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 14 of 28
May.2.19
4.3 Receivers
All the ICL32xxE devices contain standard inverting receivers, but only the ICL3245E receivers can tri-state using
the FORCEOFF control line. The ICL3245E includes 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 3kΩ to 7kΩ input impedance
(see Figure 10) 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.
The ICL3245E inverting receivers disable during forced (manual) powerdown, but not during automatic
powerdown (see Tab l e 5). Conversely, the monitor receiver remains active even during manual powerdown,
which makes 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 11
and 12). When powered down, they cannot be used for wake-up functions, but the corresponding monitor receiver
can be dedicated to this task as shown in Figure 12.
Figure 10. Inverting Receiver Connections
Figure 11. Power Drain Through Powered Down Peripheral Figure 12. Disabled Receivers Prevent Power Drain
RXOUT
GND ≤ VROUT ≤ VCC
5kΩ
RXIN
-25V ≤ VRIN ≤ +25V
GND
VCC
Old
VCC
Powered
GND SHDN = GND
VCC
Rx
Tx
VCC
Current
VOUT = VCC
Flow
RS-232 Chip
Down
UART
ICL3245E
Transition
RX
TX
R2OUTB
R2OUT
T1IN
FORCEOFF = GND
VCC
VCC
To
R2IN
T1OUT
VOUT = HI-Z
Powered
Detector
Down
UART
Wake-Up
Logic
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 15 of 28
May.2.19
4.4 Powerdown Functionality
The 3V ICL32xxE devices require a nominal supply current of 0.3mA during normal operation (not in powerdown
mode). This 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 1µA, because the on-chip charge pump turns off (V+ collapses to VCC, V- collapses to
GND), and the transmitter outputs tri-state. Inverting receiver outputs may or may not disable in powerdown; see
Tabl e 5 for details. This micro-power mode makes these devices ideal for battery powered and portable
applications.
Table 5. Powerdown Logic Truth Table
RCVR or
XMTR
EDGE
Within 30
Sec?
FORCEOFF
Input
FORCEON
Input
Transmitter
Outputs
Receiver
Outputs
ROUTB
Outputs
(Note 7)
RS-232
Level
Present at
Receiver
Input?
INVALID
Output Mode of Operation
ICL3225E, ICL3227E
No H H Active Active N.A. No L Normal Operation (Enhanced
Auto Powerdown Disabled)
No H H Active Active N.A. Yes H
Yes H L Active Active N.A. No L Normal Operation (Enhanced
Auto Powerdown Enabled)
Yes H L Ac ti ve Active N.A. Yes H
No H L High-Z Active N.A. No L Powerdown Due to Enhanced
Auto Powerdown Logic
No H L High-Z Active N.A. Yes H
X L X High-Z Active N.A. No L Manual Powerdown
X L X High-Z Active N.A. Yes H
ICL322XE - INVALID Driving FORCEON and FORCEOFF (Emulates Automatic Powerdown)
XNote 8 Note 8 Active Active N.A. Yes H Normal Operation
XNote 8 Note 8 High-Z Active N.A. No L Forced Auto Powerdown
ICL3245E
No H H Active Active Active No L Normal Operation (Enhanced
Auto Powerdown Disabled)
No H H Active Active Active Yes H
Yes H L Active Active Active No L Normal Operation (Enhanced
Auto Powerdown Enabled)
Yes H L Active Active Active Yes H
No H L High-Z Active Active No L Powerdown Due to Enhanced
Auto Powerdown Logic
No H L High-Z Active Active Yes H
X L X High-Z High-Z Active No L Manual Powerdown
X L X High-Z High-Z Active Yes H
ICL3245E - INVALID Driving FORCEON and FORCEOFF (Emulates Automatic Powerdown)
XNote 8 Note 8 Active Active Active Yes H Normal Operation
XNote 8 Note 8 High-Z High-Z Active No L Forced Auto Powerdown
Notes:
7. Applies only to the ICL3245E.
8. Input is connected to INVALID Output.
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 16 of 28
May.2.19
4.4.1 Software Controlled (Manual) Powerdown
The ICL32xxE devices allow you to force the IC into the low power, standby state, and use 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. Under logic or software control, only the FORCEOFF input
needs to be driven to switch between active and power-down modes. The FORCEON state is not critical because
FORCEOFF overrides FORCEON. However, if strictly manual control over power-down is needed, you must strap
FORCEON high to disable the automatic powerdown circuitry. The ICL3245E inverting (standard) receiver
outputs also disable when the device is in powerdown, and eliminate the possible current path through a
shutdown peripheral’s input protection diode (see Figures 11 and 12).
Connecting FORCEOFF and FORCEON together disables the enhanced automatic powerdown feature, which
enables them to function as a manual SHUTDOWN input (see Figure 13).
With any of the above control schemes, the time required to exit powerdown and resume transmission is only
100µs.
When using both manual and enhanced automatic powerdown (FORCEON = 0), the ICL32xxE devices do not
power up from manual powerdown until both FORCEOFF and FORCEON are driven high, or until a transition
occurs on a receiver or transmitter input. Figure 14 shows a circuit for ensuring that the ICL32xxE powers up as
soon as FORCEOFF switches high. The rising edge of the master powerdown signal forces the device to power
up, and the ICL32xxE returns to enhanced automatic powerdown mode an RC time constant after this rising
edge. The time constant is not critical, because the ICL32xxE remains powered up for 30 seconds after the
FORCEON falling edge, even if there are no signal transitions. The delay gives slow-to-wake systems (such as a
mouse) plenty of time to start transmitting, and as long as it starts transmitting within 30 seconds both systems
remain enabled.
4.4.2 INVALID Output
Table 5 on page 15 on the INVALID output always indicates whether 30µs have elapsed with invalid RS-232
signals (see Figures 15 and 17) persisting on all of the receiver inputs, and provides you a way to determine when
Figure 13. Connections for Manual Powerdown When No Valid Receiver Signals are Present
Figure 14. Circuit to Ensure Immediate Power Up When Exiting Forced Powerdown
Power
FORCEOFF
INVALID
CPU
I/O
FORCEON
ICL32xxE
Management
Logic
UART
FORCEOFF FORCEON
Power Master Powerdown Line
1MΩ
0.1µF
Management
Unit
ICL32xxE
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 17 of 28
May.2.19
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. If an interface cable is disconnected
and all the receiver inputs are floating (but pulled to GND by the internal receiver pull down resistors), the
INVALID logic detects the invalid levels and drives the output low. The power management logic then uses this
indicator to power down the interface block. Reconnecting the cable restores valid levels at the receiver inputs,
INVALID switches high, and the power management logic wakes up the interface block. INVALID can also be
used to indicate the DTR or RING INDICATOR signal, as long as the other receiver inputs are floating, or driven to
GND (as in the case of a powered down driver).
4.4.3 Enhanced Automatic Powerdown
Even greater power savings are available by using the ICL32xxE's enhanced automatic powerdown function.
When the enhanced powerdown logic determines that no transitions have occurred on any of the transmitter or
receiver inputs for 30 seconds, the charge pump and transmitters powerdown, and reduces supply current to 1µA.
The ICL32xxE devices automatically power back up whenever they detect a transition on one of these inputs. The
automatic powerdown feature provides additional system power savings without changes to the existing operating
system.
Enhanced automatic powerdown operates when the FORCEON input is low and the FORCEOFF input is high.
Tying FORCEON high disables automatic powerdown, but manual powerdown is always available using the
overriding FORCEOFF input. Table 5 on page 15 summarizes the enhanced automatic powerdown functionality.
Figure 16 shows the enhanced powerdown control logic. Note: When the ICL32xxE enters powerdown (manually
or automatically), the 30 second timer remains timed out (set), keeping the ICL32xxE powered down until
FORCEON transitions high, or until a transition occurs on a receiver or transmitter input.
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 17), but this has no direct effect on the state of the ICL32xxE (see the next
sections for methods of using INVALID to power down the device). INVALID switches high 1µs after detecting a
valid RS-232 level on a receiver input. INVALID operates in all modes (forced or automatic powerdown, or forced
on), so it is also useful for systems employing manual powerdown circuitry.
Figure 15. Definition of Valid RS-232 Receiver Levels
Figure 16. Enhanced Automatic Powerdown Logic
0.3V
-0.3V
-2.7V
2.7V
Invalid Level - INVALID = 0
Valid RS-232 Level - INVALID = 1
Valid RS-232 Level - INVALID = 1
Indeterminate
Indeterminate
30s
Timer
S
R
FORCEOFF
AUTOSHDN
FORCEON
R_IN
T_IN Edge
Detect
Edge
Detect
ICL3225E, ICL3227E, ICL3245E 4. Application Information
FN4900 Rev.13.00 Page 18 of 28
May.2.19
The time to recover from automatic powerdown mode is typically 100µs.
4.4.4 Emulating Standard Automatic Powerdown
If enhanced automatic powerdown is not desired, you can implement the standard automatic powerdown feature
(mimics the function on the ICL3221E/ICL3223E/ICL3243E) by connecting the INVALID output to the FORCEON
and FORCEOFF inputs, as shown in Figure 18. After 30µs of invalid receiver levels, INVALID switches low and
drives the ICL32xxE into a forced powerdown condition. INVALID switches high as soon as a receiver input
senses a valid RS-232 level, forcing the ICL32xxE to power on. See ICL322XE - INVALID Driving FORCEON
and FORCEOFF (Emulates Automatic Powerdown)” on page 15 for an operational summary. This operational
mode is perfect for handheld devices that communicate with another computer through 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 powerdown. Reconnecting the cable restores valid
levels and causes the IC to power back up.
Figure 17. Connections for Automatic Powerdown When No Valid Receiver Signals are Present
Figure 18. Enhanced Automatic Powerdown, INVALID and READY Timing Diagrams
FORCEOFF
INVALID
CPU
I/O
FORCEON
ICL32xxE
UART
Receiver
Inputs
Transmitter
Outputs
INVALID
Output
V+
VCC
0
V-
tINVL
tINVH
READY
Output
Transmitter
Inputs
tWU
tAUTOPWDN
tAUTOPWDN tWU
Invalid
Region
}