Intersil ICL32XE devices are 3.0V to 5.5V compliant with ElA/TIA-232 and V.28/V.24 specifications, even at VCC=3.0V. Additionally, ±15kV ESD protection (IEC61000-4-2 air gap and Human Body Model) is provided on the transmitter output and receiver input ( RS-232 pins). Target applications are PDAs, PDAs, notebooks and notebooks where low running, even lower standby power consumption is essential. An efficient on-chip charge pump, coupled with manual and enhanced auto-shutdown, reduces standby supply current to 1 µA. The small footprint package and the use of small, low-value capacitors also ensure board space savings. The data rate is guaranteed to be greater than 1Mbps in the worst case condition. This series is fully compatible with 3.3V systems only, mixed 3.3V and 5.0V systems, and 5.0V systems only. The ICL3245E is a 3-driver, 5-receiver device that provides a complete serial port computer suitable for laptops. It also includes an always-active receiver for the "wake up" function. These devices feature enhanced auto-shutdown of chip power and driver circuits. When all receivers and transmitters are input within 30 seconds. These devices automatically restore power at any time and they can sense the transition of any transmitter or receiver input. Table 1 summarizes the characteristics of the devices shown according to this data sheet, while application note AN9863 summarizes the 3V series containing the ICL32XE

feature

Free Pb available (see ordering information)

RS-232 input/output pins up to ±15kV ESD protection (IEC61000)

Manual and enhanced automatic power-off

Replaces MAX3225E, MAX3227E, up to 3245E

RS-232 compatible VCC=2.7V

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

no latch

On-chip voltage converter requires only 4 external 0.1µF capacitors

Guaranteed mouse drivability (ICL3245E)

Ready to Send indicator output (ICL3225E/ICL3227E)

Receiver lag for improved noise immunity

Guaranteed minimum data rate. 1 MPa

Low deviation of transmitter/receiver input trip points. 10 ns

Guaranteed minimum slew rate. 24V/µs

Wide range of power sources. Single +3V to +5.5V

Low supply current in power down state. 1 microamp

application

Any system that requires an RS-232 communication port - Battery powered, handheld and portable devices - Notebooks, notebooks, PDAs - Modems, printers and other peripherals - Digital cameras - Cellular/mobile phones

Absolute Maximum Ratings Thermal Information

VCC is grounded. -0.3V to 6V

V+ is grounded. -0.3V to 7V

voltage to ground. +0.3V to -7V

V+ to V-. 14 volts

Input voltage

Tin, strong, strong. -0.3V to 6V

Lean. 5 volts

The output voltage

touted. ? 3.2 volts

ROUT, void, ready. -0.3V to VCC+0.3V

short circuit duration

touted. continuously

Electrostatic discharge rating. see spec sheet

Thermal Resistance (Typical, Note 3) θJA (Celsius/Watt)

20 Ld PDIP packets. 80

28 Ld SOIC package. 75

16 Ld SSOP packs. 145

20 Ld SSOP pack. 135

28 Ld SSOP packs. 100

Maximum Junction Temperature (Plastic Packaging). 150 degrees Celsius

Maximum storage temperature range. -65°C to 150°C

Maximum lead temperature (10s for soldering). 300 degrees Celsius (SOIC, SSOP - lead only)

operating conditions

temperature range

ICL32XEC. 0°C to 70°C

ICL32XEI. -40°C to 85°C

CAUTION: Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a pressure rating and operation of the device under the above or any other conditions stated in the operating section of this specification is not implied.

Note:

1. θJA is measured in free air with components mounted on an inefficient thermal conductivity test board. See Technical Bulletin TB379 for details.

Electrical specification test conditions: VCC=3V～5.5V, C1～C4=0.1mF; unless otherwise specified. Typical temperature is TA=25 oC

Electrical specification test conditions: VCC=3V～5.5V, C1～C4=0.1μF; unless otherwise specified. Typical temperature is TA=25°C (continued)

notes:

2. "Edge" is defined as the transition through the transmitter or receiver input threshold.

3. Measure the deviation at the receiver input switch point (1.4V)

Detailed description

These ICL32XE interface ICs operate from a single +3V to +5.5V supply, guarantee a minimum data rate of 1Mbps, require only four small external 0.1µF capacitors, feature low power consumption, and meet all ElA RS-232C and V.28 specifications . The circuit is divided into three parts: charge pump, transmitter and receiver. Charge Pumps Intersil's new ICL32XE family employs a regulated on-chip dual charge pump as a voltage doubler and an inverter that generates ±5.5V transmitter power from VCC to provide power as low as 3.0V. This allows these devices to maintain RS-232 compatible output levels over the range of ±10% tolerance 3.3V powered systems. An effective on-chip power supply requires only four small external 0.1µF capacitors for voltage doubler and inverter functions, VCC = 3.3V. See the Capacitor Selection section and Table 3 for capacitor recommendations for other operating conditions. The priming pump operates discontinuously (i.e. shuts down once the V+ and V- supplies are delivered to nominal), resulting in significant power savings. Transmitter The transmitter is a proprietary, low loss, inversion that converts TTL/CMOS inputs to EIA/TIA-232 driver output levels. Coupled with on-chip ±5.5V power supplies, these transmitters provide a true RS-232 level single-supply system voltage range over a wide range. The transmitter output is disabled and assumes the state when the high-impedance device enters shutdown mode (see Table 2). when disabled.

All devices are guaranteed for 1Mbps data rate conditions at full load (3kΩ and 250pF), VCC ≥ 3.0V, with one transmitter running at full speed. Under more typical conditions of VCC≥3.3V, RL=3kΩ, CL=250pF, 1 transmitter can easily work at 1.4Mbps. Transmitter tilt is very low on these devices and is at the receiver input trigger point (1.4V), not any 0V typical of other RS-232 series crossover points. If not connected, the transmitter input will float and may cause the ICC to increase. It is best to connect unused inputs to the GND meter.

receiver

All ICL32XE devices contain a standard reversal receiver, but only the ICL3245E receiver can pass the force of the control line. In addition, the ICL3245E includes a non-vertical (monitor) receiver (by the ROUTB label) that is always active regardless of any control lines. Both receiver types convert RS-232 signals to CMOS output levels and accept inputs up to ±25V while providing the required 3kΩ to 7kΩ input impedance (see Figure 1) even when powered down (VCC = 0V). The Schmitt Trigger input stage of this receiver uses hysteresis to improve noise immunity and reduce erroneous input signal transitions due to slow speeds. The ICL3245E reversing receiver is disabled (manual) during forced power down, but not during automatic power down (see Table 2). Instead, the monitor receiver remains active for ring indicator monitoring even when manually powered down. Peripherals with standard receivers shutting down drive power must disable the protection diodes that prevent current flow through the peripheral (see Figures 2 and 3). This makes them useless for the wake-up function, but the corresponding monitor receiver can be dedicated to this task, as shown in Figure 3.

notes:

4. For ICL3245E only.

5. The input is connected to the invalid output.

Power off function

This 3V series RS-232 interface device requires a nominal supply current of 0.3mA during normal operation (not in shutdown mode). This is 5mA to 11mA more current than a 5V RS-232 device. This is when the device goes into shutdown mode. On power down, the supply current drops to 1 µA because the on-chip charge pump is turned off (V+ is folded to VCC, V- is folded to GND), and the transmitter output is tri-stated. The reverse receiver output may or may not be disabled when powered down; see Table 2 for details. This micropower mode makes these devices ideal for battery powered and portable applications. Software-controlled (manual) power down These three devices allow the user to force the IC into a low-power, standby state, and employ a two-pin approach where the FORCEON and FORCEOFF inputs determine the IC mode. Both FORCE and FORCEOFF are tied high for always-enabled operations. Toggling the active and power down mode controls under logic or software, simply drive the FORCEOFF input. This FORCEON state doesn't matter because FORCEOFF dominates too hard. However, if a power-off is required for strict manual control, the user must bring the force high to disable the enhanced automatic power-off circuit. The ICL3245E inverting (standard) receiver output is also disabled when the device is powered down, thus eliminating a possible current path protection diode (see Figures 2 and 3) by turning off the peripheral input. Connecting FORCEOFF and FORCEON together disables the enhanced auto-shutdown feature, making them available as manual shutdown inputs (see Figure 4). For any of the above control schemes, the time required to exit a power-down and resume transmission is only 100 microseconds.

When using both manual and enhanced auto power down (FORCEON=0), the ICL32XE will not power up from manual power down to forced off and force is driven high, or until receiver or transmitter input. Figure 5 illustrates ensuring that the ICL32XE is switched high in the forced shutdown. The master's rising edge power down signal forces the device to power up the ICL32XE to return to enhanced auto power off mode with the RC time constant after the rising edge. The time constant is not very important because the ICL32XE is 30 seconds after the edge of the force drop, even with no signal transition. This gives a slow wake-up system (e.g. a mouse) enough time to start the transfer, and as long as it starts the transfer within 30 seconds both systems remain enabled.

invalid output

Invalid output always indicates (see Table 2) whether or not for more than 30 microseconds, the RS-232 signal is invalid (see Figures 6 and 8) holding all receiver inputs, providing the user with an easy way to determine when the block should be Power off. The receive level is invalid when the output of the driver peripheral is turned off (power off) or the RS-232 interface cable is disconnected. If the interface cable is disconnected all receiver inputs are floating (but pulled to GND through the internal receiver pull-down resistors), the invalid logic detects invalid levels and drives the output low. The power management logic then uses this LED to supply power under the interface block. Reconnecting the cable restores the active level of the receiver input, the inactive switch is high, and the power management logic wakes the interface blocked. INVALID can also be used to indicate a DTR or ring indicator signal as long as the other receiver input is floating, or driven to GND (such as turning off the driver).

Enhanced automatic shutdown

Use these devices to save even more power with an enhanced automatic power-off feature. When the enhanced power-down logic determines that any transmitter or receiver has a transition input for 30 seconds, the charge pump and transmitter are powered down, reducing supply current to 1 µA when the ICL32XE detects a transition on one of these inputs. Auto Shutdown This feature does not use changes to existing operating systems. When the FORCEON input is low, the FORCEOFF input is high. High tie-down force will disable automatic power-off, but manual power-off can always be used to force the input to shut down via an override. Table 2 summarizes the enhanced automatic power-off function

Figure 7 illustrates the enhanced power down control logic. Note that once the ICL32XE goes into a powered down state (manual (set), keep the ICL32XE powered down until forced transition high, or until a receiver transition occurs, or until a transmitter input. The inactive output signal switches low, indicating all receiver inputs There are invalid levels greater than 30 microseconds on all (see Figure 8), but this has no direct effect on the state of the ICL32XE (about the method of shutting down the device with INVALID). After a valid RS-232 is detected, the invalid switch is high for 1 microsecond to receive input level. Inactive operation in all modes (forced or automatic power off, or forced open), therefore suitable for systems with manual power-off circuits. Recovery time from automatic power-off mode is typically 100 microseconds. Analog standard Auto-Shutdown If enhanced auto-shutdown is not required, the user can implement the standard auto-power-off function (mimicsICL3221E/ICL3223E/ICL3243E) by connecting the inactive output to the FORCEON and forced shutdown input as shown in Figure 9. After 30 µs Invalid receiver level, invalid switch is low and drives ICL32XE into forced power-off state. Invalid once the receiver input detects a valid RS, it immediately switches to high level -232 level, forcing ICL32XE to power on. See "Invalid Table 2" "Drive and Force" section for a summary of operation. This mode of operation works well with a detachable cable. Splitting the cable allows the internal receiver pull-down resistor to pull the input to GND (invalid RS-232 level), resulting in 30 micron Second timer times out and drives the IC into a power-down state. Reconnecting the cable restores active levels to restore power to the IC (A or Auto), 30-second timer hold timeout Hybrid auto power-off option for via detachable cable only, Connecting inactive to FORCEOFF (with FORCEON=0) might be the ideal configuration. When the cable is attached inactive and force remains high, so the enhanced auto-power-down logic powers down RS-232 devices as long as the receiver and transmitter inputs are separated. The cable allows the receiver input to drop to an inactive level (GND), thus inactive low switching and forcing the RS-232 device to power down. The ICL32XE remains powered down until the cable is reconnected (inactive=FORCEOFF=1) and the receiver or Transmitter input transitions (see Figure 7), when the cable is reconnected, through a network similar to that shown in Figure 5.

Ready output (ICL3225E and ICL3227E only) The ready output indicates that the ICL322XE is ready to transmit. The ready switch de-energizes low when the device is in, and switches back to high when V- reaches -4V or lower. Capacitor Selection The charge pump requires a 3.3V 0.1µF capacitor to operate. See Table 3 for capacitance values for other supply voltages. Do not use values smaller than those listed in Table 3. Increasing the capacitor value (by a factor of 2) reduces the ripple at the transmitter output and slightly reduces power consumption. C2, C3, and C4 can be values that increase without increasing C1, however, increasing C1 without increasing C2, C3, and C4 maintains the proper ratio (ratio of C1 to other capacitors). When using the minimum required capacitance value, make sure that the capacitance value does not vary with temperature. When in doubt, use a capacitor with a larger nominal value. Capacitor Equivalent Series Resistance (ESR) typically rises at low temperatures and it affects the amount of ripple on V+ and V-.

Power decoupling

In most cases, a 0.1µF bypass capacitor is sufficient. For power supply noise, use a capacitor of the same value as the charge pump capacitor C1. Place bypass capacitors as close to the IC as possible. Operating voltage down to 2.7V The ICL32XE transmitter output meets RS-562 levels (±3.7V) with VCC as low as 2.7V at full data rate. RS-562 levels generally ensure interoperability with RS-232 equipment. Transmitter outputs upon exiting power down Figure 10 shows the response of both transmitter outputs when exiting shutdown mode. Transmitter outputs go correctly to opposite RS-232 levels when they are activated, with no flickering, rattling, or unwanted transients. Each transmitter is loaded with 3kΩ in parallel with 2500pF. Note only when the power supply exceeds about 3V. Mouse Maneuverability The ICL3245E is designed to power a serial mouse when operating from a low voltage power supply. Figure 11 shows the transmitter output voltage with increasing load current. This on-chip switching regulator ensures that the transmitter is powered at least ±5V worst-case (15mAV+ transmitters in parallel, 7.3mA for single V- transmitters).

high data rate

The ICL32XE maintains the RS-232 ±5V minimum output voltage from the transmitter even at high data rates. Figure 12 details the transmitter loopback test circuit and Figure 13 demonstrates the loopback test results at 250kbps. For this test, all transmitters simultaneously drive an RS-232 load in parallel with 1000pF, 250kbps. Figure 14 shows driving an RS-232 load of 250pF and 1 megabyte per second. The electrostatic transmitter is equipped with an RS-232 receiver.

3V and 5V logic interface The ICL32XE interfaces directly with the 5V CMOS and TTL logic families. Nonetheless, logic supplies from 5V, AC, HC, and CD4000 outputs can drive the ICL32XX inputs when the ICL32XX is at 3.3V, but the ICL32XX outputs do not reach the minimum VIH for these logic families. See Table 4 for details.

±5kV ESD Protection All pins on the ICL32XX devices include ESD protection structures, but the ICL32XE family employs an advanced structure that allows RS-232 pins (transmitter outputs as well as receiver inputs) to operate at up to ±15k volts of electrostatic discharge events. The RS-232 pins are particularly vulnerable to ESD damage as they are usually connected to the finished look. Simply touching port pins or connecting cables can cause an ESD event that can destroy an unprotected IC. These new ESD structures protect the device from not allowing any locking mechanisms to activate, whether the device is powered or not, and do not interfere with the ±25V RS-232 signal.

Human model test

As the name suggests, this test method simulates ESD events passing to the IC during manual handling. The tester supplied the charge through a 1.5kΩ current limiting resistor, making the test less severe than the IEC61000 test with a 330Ω limiting resistor. The HBM method to determine the ability of an IC to withstand ESD transients typically occurs during handling and manufacturing. Due to the randomness of these events, each pin is used to respect all other pins. RS-232 pin devices on the "E" series can withstand HBM ESD events to ±15kV. IEC61000-4-2 Test The IEC61000 test method applies to a finished device, not a stand-alone integrated circuit. So the ones most likely to suffer from ESD events are those exposed to the outside world (in this case the RS-232 pins) and the IC is tested in its typical application configuration (power up) rather than testing each pin for The combination. The lower layer with a large charge-coupled current-limiting resistive storage capacitor yields a test better than the HBM test. Built-in RS-232 pins for additional ESD protection devices allow designing equipment to meet Class 4 standards without adding level protection on the board's RS-232 ports. Air Gap Discharge Test Method For this test method, the tip of the live probe is pointed toward the IC pin until the voltage arcs to it. The current waveform delivered to the IC pins depends on approach speed, humidity, temperature, etc., so it is difficult to obtain repeatable results. The "E" device RS-232 pin withstands ±5kV air gap discharge. Contact Discharge Test Method During a contact discharge test, the probe contacts the test pin before the probe tip is energized, thus eliminating the variables associated with the air gap. The result is a more repeatable and predictable test, but device limitations prevent testing the device at voltages higher than ±8kV. All "E" series devices can withstand ±8kV contact voltage RS-232 pin discharge.