ICL3244 TM Data Sheet June 2000 1Microamp, +3V to +5.5V, 250kbps, RS-232 Transceiver with Enhanced Automatic Powerdown The ICL3244 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. This device, features an enhanced automatic powerdown function which powers down the on-chip power-supply and driver circuits. This occurs when all receiver and transmitter inputs detect no signal transitions for a period of 30s. The ICL3244 powers back up, automatically, whenever it senses a transition on any transmitter or receiver input. • • • • • • • • • • • Manual and Enhanced Automatic Powerdown Features Drop in Replacement for MAX3244 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 Guaranteed Mouse Driveability Receiver Hysteresis For Improved Noise Immunity Guaranteed Minimum Data Rate . . . . . . . . . . . . 250kbps Guaranteed Minimum Slew Rate . . . . . . . . . . . . . . . 6V/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 - Cellular/Mobile Phones • Related Literature - Application Note AN9863, “3V to +5.5V, 250k-1Mbps, RS-232 Transmitters/Receivers” Pinout ICL3244 (SOIC, SSOP) TOP VIEW Table 1 summarizes the features of the device represented by this data sheet, while Application Note AN9863 summarizes the features of each device comprising the ICL3244 3V family. ICL3244CA ICL3244CB 0 to 70 PACKAGE 28 Ld SSOP 0 to 70 PKG. NO. M28.209 28 Ld SOIC C2+ 1 28 C1+ C2- 2 27 V+ 3 26 VCC R1IN 4 25 GND R2IN 5 24 C1- R3IN 6 23 FORCEON R4IN 7 22 FORCEOFF R5IN 8 21 INVALID T1OUT 9 20 R2OUTB T2OUT 10 19 R1OUT T3OUT 11 18 R2OUT T3IN 12 17 R3OUT T2IN 13 16 R4OUT T1IN 14 15 R5OUT V- Ordering Information PART NO. 4876 Features The Intersil ICL32XX devices are 3.0V to 5.5V powered RS-232 transmitters/receivers which meet ElA/TIA-232 and V.28/V.24 specifications, even at VCC = 3.0V. Targeted applications are PDAs, Palmtops, and notebook and laptop computers where the low operational, and even lower standby, power consumption is critical. Efficient on-chip charge pumps, coupled with manual and enhanced automatic 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 as well. Data rates greater than 250kbps are guaranteed 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. TEMP. RANGE (oC) File Number M28.3 NOTE: Most surface mount devices are available on tape and reel; add “-T” to suffix. TABLE 1. SUMMARY OF FEATURES PART NUMBER ICL3244 NO. OF NO. OF Tx. Rx. 3 5 4-1 NO. OF MONITOR Rx. (ROUTB) DATA RATE (kbps) Rx. ENABLE FUNCTION? 1 250 No READY OUTPUT? MANUAL POWERDOWN? ENHANCED AUTOMATIC POWERDOWN FUNCTION? No Yes Yes CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil and Design is a trademark of Intersil Corporation. | Copyright © Intersil Corporation 2000 ICL3244 Pin Descriptions PIN VCC FUNCTION 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. TOUT RS-232 Level (Nominally ±5.5V) Transmitter Outputs. RIN RS-232 Compatible Receiver Inputs. ROUT TTL/CMOS Level Receiver Outputs. ROUTB TTL/CMOS Level, Noninverting, Always Enabled Receiver Outputs. INVALID Active Low Output that indicates if no valid RS-232 levels are present on any receiver input. FORCEOFF Active Low to Shut Down Transmitters and On-Chip Power Supply. This overrides any automatic circuitry and FORCEON (see Table 2). FORCEON Active High Input to override automatic powerdown circuitry thereby keeping transmitters active. (FORCEOFF must be high). Typical Operating Circuit ICL3244 +3.3V + 26 0.1µF 28 C1 0.1µF + C2 0.1µF C11 C2+ + 2 C2- C1+ VCC 24 27 + V+ C3 0.1µF ICL3244 VT1 14 9 T1IN T2 13 3 C4 0.1µF + T1OUT 10 T2IN T2OUT T3 12 RS-232 LEVELS 11 T3IN T3OUT 20 R2OUTB 19 4 R1OUT R1IN R1 TTL/CMOS LOGIC LEVELS 5kΩ 18 5 R2OUT R2IN R2 5kΩ R3 5kΩ 17 6 R3OUT 16 7 R4OUT R4IN R4 5kΩ 15 8 R5OUT R5IN 23 5kΩ R5 FORCEON VCC TO POWER CONTROL LOGIC 22 FORCEOFF 21 INVALID GND 25 4-2 R3IN RS-232 LEVELS ICL3244 Absolute Maximum Ratings Thermal Information VCC to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V V- to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V Input Voltages TIN, FORCEOFF, FORCEON. . . . . . . . . . . . . . . . . . . -0.3V to 6V RIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±25V Output Voltages TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±13.2V ROUT, INVALID. . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VCC +0.3V Short Circuit Duration TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table Thermal Resistance (Typical, Note 1) θJA (oC/W) 28 Ld SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . 75 28 Ld SSOP Package . . . . . . . . . . . . . . . . . . . . . . . 100 Moisture Sensitivity (see Technical Brief TB363) All Packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1 Maximum Junction Temperature (Plastic Package) . . . . . . . 150oC Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC (SOIC, SSOP- Lead Tips Only) Operating Conditions Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to 70oC CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTE: 1. θJA is measured with the component mounted on an evaluation PC board in free air. Electrical Specifications Test Conditions: VCC = 3V to 5.5V, C1 - C4 = 0.1µF; Unless Otherwise Specified. Typicals are at TA = 25oC PARAMETER TEST CONDITIONS TEMP (oC) MIN TYP MAX UNITS 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 Full - - 0.8 V VCC = 3.3V Full 2.0 - - V VCC = 5.0V Full 2.4 - - V LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low TIN, FORCEON, FORCEOFF Input Logic Threshold High TIN, FORCEON, FORCEOFF Input Leakage Current TIN, FORCEON, FORCEOFF Full - ±0.01 ±1.0 µA Output Leakage Current FORCEOFF = GND Full - ±0.05 ±10 µA Output Voltage Low IOUT = 1.6mA Full - - 0.4 V Output Voltage High IOUT = -1.0mA Full - V 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 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 kΩ Full ±5.0 ±5.4 - V Input Threshold Low Input Threshold High TRANSMITTER OUTPUTS Output Voltage Swing All Transmitter Outputs Loaded with 3kΩ to Ground 4-3 ICL3244 Electrical Specifications Test Conditions: VCC = 3V to 5.5V, C1 - C4 = 0.1µF; Unless Otherwise Specified. Typicals are at TA = 25oC (Continued) TEMP (oC) MIN TYP MAX UNITS Full 300 10M - Ω Full - ±35 ±60 mA VOUT = ±12V, VCC = 0V or 3V to 5.5V, Automatic Powerdown or FORCEOFF = GND Full - - ±25 µA T1IN = T2IN = GND, T3IN = VCC, T3OUT Loaded with 3kΩ to GND, T1OUT and T2OUT Loaded with 2.5mA Each Full ±5 - - V PARAMETER TEST CONDITIONS VCC = V+ = V- = 0V, Transmitter Output = ±2V Output Resistance Output Short-Circuit Current Output Leakage Current MOUSE DRIVEABILITY Transmitter Output Voltage (Figure 11) ENHANCED AUTOMATIC POWERDOWN (FORCEON = GND, FORCEOFF = VCC) Receiver Input Thresholds to INVALID High ICL3244 Powers Up (Figure 6) Full -2.7 - 2.7 V Receiver Input Thresholds to INVALID Low ICL3244 Powers Down (Figure 6) Full -0.3 - 0.3 V INVALID Output Voltage Low IOUT = 1.6mA Full - - 0.4 V INVALID Output Voltage High IOUT = -1.0mA Full VCC-0.6 - - V Receiver Positive or Negative Threshold to INVALID High Delay (tINVH) 25 - 1 - µs Receiver Positive or Negative Threshold to INVALID Low Delay (tINVL) 25 - 30 - µs Receiver or Transmitter Edge to Transmitters Enabled Delay (tWU) Note 2 25 - 100 - µs Receiver or Transmitter Edge to Transmitters Enabled Delay (tAUTOPWDN) Note 2 Full 15 30 60 s Maximum Data Rate RL = 3kΩ, CL = 1000pF, One Transmitter Switching Full 250 500 - kbps Receiver Propagation Delay Receiver Input to Receiver Output, CL = 150pF tPHL 25 - 0.15 - µs tPLH 25 - 0.15 - µs TIMING CHARACTERISTICS Receiver Output Enable Time Normal Operation 25 - 200 - ns Receiver Output Disable Time Normal Operation 25 - 200 - ns Transmitter Skew tPHL - tPLH 25 - 100 - ns Receiver Skew tPHL - tPLH 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 6 - 30 V/µs CL = 150pF to 2500pF 25 4 8 30 V/µs Human Body Model 25 - >±8 - kV IEC1000-4-2 Contact Discharge 25 - ±8 - kV IEC1000-4-2 Air Gap Discharge 25 - ±8 - kV Human Body Model 25 - ±3 - kV ESD PERFORMANCE RS-232 Pins (TOUT, RIN) All Other Pins NOTE: 2. An “edge” is defined as a transition through the transmitter or receiver input thresholds. 4-4 ICL3244 Detailed Description ICL32XX interface ICs operate from a single +3V 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. The circuit is divided into three sections: The charge pump, the transmitters, and the receivers. Charge-Pump Intersil’s new ICL32XX family utilizes regulated on-chip dual charge pumps as voltage doublers, and voltage inverters to generate ±5.5V transmitter supplies from a VCC supply as low as 3.0V. This allows these devices to maintain RS-232 compliant output levels over the ±10% tolerance range of 3.3V powered systems. The efficient on-chip power supplies require only four small, external 0.1µF capacitors for the voltage doubler and inverter functions at VCC = 3.3V. See the “Capacitor Selection” section, and Table 3 for capacitor recommendations for other operating conditions. 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. Transmitter outputs disable and assume a high impedance state when the device enters the powerdown mode (see Table 2). These outputs may be driven to ±12V when disabled. All devices guarantee a 250kbps data rate for full load conditions (3kΩ and 1000pF), 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 1Mbps. Transmitter inputs float if left unconnected, and may cause ICC increases. Connect unused inputs to GND for the best performance. Receivers The ICL3244 contains both standard inverting, tri-stable receivers, and a single 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 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. The inverting receivers disable during forced (manual) powerdown, but not during automatic powerdown (see Table 2). Conversely, the monitor receiver remains active even TABLE 2. POWERDOWN LOGIC TRUTH TABLE RCVR OR XMTR EDGE WITHIN 30 SEC? FORCEOFF FORCEON TRANSMITTER RECEIVER ROUTB INPUT INPUT OUTPUTS OUTPUTS OUTPUTS RS-232 LEVEL PRESENT AT RECEIVER INPUT? INVALID OUTPUT MODE OF OPERATION ICL3244 NO H H Active Active Active No L NO H H Active Active Active Yes H YES H L Active Active Active No L YES H L Active Active Active Yes H NO H L High-Z Active Active No L NO H L High-Z Active Active Yes H X L X High-Z High-Z Active No L X L X High-Z High-Z Active Yes H Normal Operation (Enhanced Auto Powerdown Disabled) Normal Operation (Enhanced Auto Powerdown Enabled) Powerdown Due to Enhanced Auto Powerdown Logic Manual Powerdown ICL3244 - INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWERDOWN) X Note 3 Note 3 Active Active Active Yes H Normal Operation X Note 3 Note 3 High-Z High-Z Active No L Forced Auto Powerdown NOTE: 3. Input is connected to INVALID Output. 4-5 ICL3244 during manual powerdown making it extremely useful for Ring Indicator monitoring. Standard receivers driving powered down peripherals must be disabled to prevent current flow through the peripheral’s protection diodes (see Figures 2 and 3). This renders them useless for wake up functions, but the corresponding monitor receiver can be dedicated to this task as shown in Figure 3. VCC RXIN Software Controlled (Manual) Powerdown RXOUT -25V ≤ VRIN ≤ +25V 5kΩ GND ≤ VROUT ≤ VCC GND FIGURE 1. INVERTING RECEIVER CONNECTIONS VCC VCC CURRENT FLOW VCC VOUT = VCC Rx POWERED DOWN UART Tx SHDN = GND GND 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 three-state. Inverting receiver outputs may or may not disable in powerdown; refer to Table 2 for details. This micro-power mode makes this device ideal for battery powered and portable applications. The ICL3244 allows the user to force the IC into the low power, standby state, and utilizes 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 powerdown 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 powerdown is desired, the user must strap FORCEON high to disable the enhanced automatic powerdown circuitry. ICL3244 inverting (standard) receiver outputs also disable when the device is in powerdown, thereby eliminating the possible current path through a shutdown peripheral’s input protection diode (see Figures 2 and 3). Connecting FORCEOFF and FORCEON together disables the enhanced automatic powerdown feature, enabling them to function as a manual SHUTDOWN input (see Figure 4). OLD RS-232 CHIP FIGURE 2. POWER DRAIN THROUGH POWERED DOWN PERIPHERAL FORCEOFF PWR MGT LOGIC FORCEON VCC INVALID ICL3244 TRANSITION DETECTOR TO WAKE-UP LOGIC ICL3244 I/O UART VCC CPU R2OUTB RX POWERED DOWN UART VOUT = HI-Z R2OUT TX R2IN T1IN T1OUT FORCEOFF = GND FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN Powerdown Functionality This 3V RS-232 interface device requires a nominal supply current of 0.3mA during normal operation (not in powerdown mode). This is considerably less than the 5mA to 11mA 4-6 FIGURE 4. CONNECTIONS FOR MANUAL POWERDOWN WHEN NO VALID RECEIVER SIGNALS ARE PRESENT 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 ICL3244 won’t 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 5 illustrates a circuit for ICL3244 ensuring that the ICL3244 powers up as soon as FORCEOFF switches high. The rising edge of the Master Powerdown signal forces the device to power up, and the ICL3244 returns to enhanced automatic powerdown mode an RC time constant after this rising edge. The time constant isn’t critical, because the ICL3244 remains powered up for 30 seconds after the FORCEON falling edge, even if there are no signal transitions. This gives slow-to-wake systems (e.g., a mouse) plenty of time to start transmitting, and as long as it starts transmitting within 30 seconds both systems remain enabled. POWER MANAGEMENT UNIT MASTER POWERDOWN LINE 0.1µF FORCEOFF 1MΩ FORCEON FIGURE 5. CIRCUIT TO ENSURE IMMEDIATE POWER UP WHEN EXITING FORCED POWERDOWN 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). Enhanced Automatic Powerdown Even greater power savings is available by using this device which features an enhanced automatic powerdown function. When the enhanced powerdown logic determines that no transitions have occurred on any of the transmitter nor receiver inputs for 30 seconds, the charge pump and transmitters powerdown, thereby reducing supply current to 1µA. The ICL3244 automatically powers back up whenever it detects a transition on one of these inputs. This 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 via the overriding FORCEOFF input. Table 2 summarizes the enhanced automatic powerdown functionality. FORCEOFF INVALID Output T_IN The INVALID output always indicates (see Table 2) whether or not 30µs have elapsed with invalid RS-232 signals (see Figures 6 and 8) persisting on all of the receiver inputs, VALID RS-232 LEVEL - INVALID = 1 2.7V EDGE DETECT S 30s TIMER R_IN AUTOSHDN R EDGE DETECT INDETERMINATE FORCEON 0.3V INVALID LEVEL - INVALID = 0 FIGURE 7. ENHANCED AUTOMATIC POWERDOWN LOGIC -0.3V INDETERMINATE -2.7V VALID RS-232 LEVEL - INVALID = 1 FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS 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 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 4-7 Figure 7 illustrates the enhanced powerdown control logic. Note that once the ICL3244 enters powerdown (manually or automatically), the 30 second timer remains timed out (set), keeping the ICL3244 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 8), but this has no direct effect on the state of the ICL3244 (see the next sections for methods of utilizing 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. The time to recover from automatic powerdown mode is typically 100µs. ICL3244 RECEIVER INPUTS } INVALID REGION TRANSMITTER INPUTS TRANSMITTER OUTPUTS tINVH INVALID OUTPUT tINVL tAUTOPWDN tAUTOPWDN tWU tWU V+ VCC 0 V- FIGURE 8. ENHANCED AUTOMATIC POWERDOWN, AND INVALID TIMING DIAGRAMS For devices which communicate only through a detachable cable, connecting INVALID to FORCEOFF (with FORCEON = 0) may be a desirable configuration. While the cable is attached INVALID and FORCEOFF remain high, so the enhanced automatic powerdown logic powers down the RS232 device whenever there is 30 seconds of inactivity on the receiver and transmitter inputs. Detaching the cable allows the receiver inputs to drop to an invalid level (GND), so INVALID switches low and forces the RS-232 device to power down. The ICL3244 remains powered down until the cable is reconnected (INVALID = FORCEOFF = 1) and a transition occurs on a receiver or transmitter input (see Figure 7). For immediate power up when the cable is reattached, connect FORCEON to FORCEOFF through a network similar to that shown in Figure 5. FORCEOFF If enhanced automatic powerdown isn’t desired, the user can implement the standard automatic powerdown feature (mimics the function on the ICL3221/23/43) by connecting the INVALID output to the FORCEON and FORCEOFF inputs, as shown in Figure 9. After 30µs of invalid receiver levels, INVALID switches low and drives the ICL3244 into a forced powerdown condition. INVALID switches high as soon as a receiver input senses a valid RS-232 level, forcing the ICL3244 to power on. See the “INVALID DRIVING FORCEON AND FORCEOFF” section of Table 2 for an operational summary. This operational mode is perfect for handheld devices that communicate with another computer via a detachable cable. Detaching the cable allows the internal receiver pull-down resistors to pull the inputs to GND (an invalid RS-232 level), causing the 30µs timer to time-out and drive the IC into powerdown. Reconnecting the cable restores valid levels, causing the IC to power back up. FORCEON Hybrid Automatic Powerdown Options INVALID Emulating Standard Automatic Powerdown ICL3244 I/O UART Capacitor Selection The charge pumps require 0.1µF capacitors for 3.3V operation. For other supply voltages refer to Table 3 for capacitor values. Do not use values smaller than those listed in Table 3. 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 3. REQUIRED CAPACITOR VALUES CPU FIGURE 9. CONNECTIONS FOR AUTOMATIC POWERDOWN WHEN NO VALID RECEIVER SIGNALS ARE PRESENT 4-8 VCC (V) C1 (µF) C2, C3, C4 (µF) 3.0 to 3.6 0.1 0.1 4.5 to 5.5 0.047 0.33 3.0 to 5.5 0.1 0.47 ICL3244 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. 5 VOUT+ 4 3 VCC = 3.0V 2 1 T1 0 VOUT+ -1 T2 -2 ICL3244 -3 VCC -4 VOUT - T3 VOUT - -5 -6 1 0 3 2 5 4 7 6 8 9 10 LOAD CURRENT PER TRANSMITTER (mA) Transmitter Outputs when Exiting Powerdown Figure 10 shows the response of two transmitter outputs when exiting powerdown 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 3kΩ in parallel with 2500pF. Note that the transmitters enable only when the magnitude of the supplies exceed approximately 3V. 5V/DIV 6 TRANSMITTER OUTPUT VOLTAGE (V) 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-. FORCEOFF T1 2V/DIV FIGURE 11. TRANSMITTER OUTPUT VOLTAGE vs LOAD CURRENT (PER TRANSMITTER, i.e., DOUBLE CURRENT AXIS FOR TOTAL VOUT+ CURRENT) High Data Rates The ICL3244 maintains the RS-232 ±5V minimum transmitter output voltages even at high data rates. Figure 12 details a transmitter loopback test circuit, and Figure 13 illustrates the loopback test result at 120kbps. For this test, all transmitters were simultaneously driving RS-232 loads in parallel with 1000pF, at 120kbps. Figure 14 shows the 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 + 0.1µF T2 + C1+ VCC V+ C1 VCC = +3.3V C1 - C4 = 0.1µF C1- + C3 ICL3244 TIME (20µs/DIV.) FIGURE 10. TRANSMITTER OUTPUTS WHEN EXITING POWERDOWN + C2 Mouse Driveability ROUT 4-9 C4 + C2TIN The ICL3244 is specifically designed to power a serial mouse while operating from low voltage supplies. Figure 11 shows the transmitter output voltages under increasing load current. The on-chip switching regulator ensures the transmitters will supply at least ±5V during worst case conditions (15mA for paralleled V+ transmitters, 7.3mA for single V- transmitter). V- C2+ EN VCC TOUT RIN 1000pF 5k SHDN OR FORCEOFF FIGURE 12. TRANSMITTER LOOPBACK TEST CIRCUIT ICL3244 5V/DIV. T1IN T1OUT R1OUT VCC = +3.3V C1 - C4 = 0.1µF 5µs/DIV. FIGURE 13. LOOPBACK TEST AT 120kbps 5V/DIV. T1IN T1OUT R1OUT VCC = +3.3V C1 - C4 = 0.1µF 2µs/DIV. FIGURE 14. LOOPBACK TEST AT 250kbps Interconnection with 3V and 5V Logic The ICL3244 directly interfaces with most 5V logic families, including ACT and HCT CMOS. See Table 4 for more information on possible combinations of interconnections. TABLE 4. 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 COMPATIBILITY Compatible with all CMOS families. Compatible with all TTL and CMOS logic families. Compatible with ACT and HCT CMOS, and with TTL. Incompatible with AC, HC, or CD4000 CMOS. 4-10 ICL3244 Typical Performance Curves VCC = 3.3V, TA = 25oC 25 VOUT+ 4 +SLEW 20 SLEW RATE (V/µs) TRANSMITTER OUTPUT VOLTAGE (V) 6 2 1 TRANSMITTER AT 250kbps 1 OR 2 TRANSMITTERS AT 30kbps 0 -2 15 -SLEW 10 -4 VOUT +SLEW -6 0 1000 2000 3000 4000 5 5000 0 1000 2000 3000 FIGURE 15. TRANSMITTER OUTPUT VOLTAGE vs LOAD CAPACITANCE 3.5 NO LOAD ALL OUTPUTS STATIC 3.0 SUPPLY CURRENT (mA) 40 SUPPLY CURRENT (mA) 5000 FIGURE 16. SLEW RATE vs LOAD CAPACITANCE 45 250kbps 35 4000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) 30 25 120kbps 20 2.5 2.0 1.5 1.0 0.5 15 20kbps 10 0 1000 2000 3000 4000 5000 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) LOAD CAPACITANCE (pF) FIGURE 18. SUPPLY CURRENT vs SUPPLY VOLTAGE FIGURE 17. SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA Die Characteristics DIE DIMENSIONS: PASSIVATION: 100 mils x 127 mils (2550µm x 3230µm) METALLIZATION: Type: Metal 1: AISi (1%) Thickness: Metal 1: 8kÅ Type: Metal 2: AISi (1%) Thickness: Metal 2: 10kÅ Type: Silox Thickness: 13kÅ TRANSISTOR COUNT: 1109 PROCESS: Si Gate CMOS SUBSTRATE POTENTIAL (POWERED UP): GND 4-11 6.0 ICL3244 Shrink Small Outline Plastic Packages (SSOP) M28.209 (JEDEC MO-150-AH ISSUE B) N 28 LEAD SHRINK SMALL OUTLINE PLASTIC PACKAGE INDEX AREA H 0.25(0.010) M B M INCHES E GAUGE PLANE -B1 2 3 L 0.25 0.010 SEATING PLANE -A- A D -C- α e B 0.25(0.010) M 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. 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. 4-12 SYMBOL MIN 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 A2 A1 MILLIMETERS 0.026 BSC H 0.292 L 0.022 N α 0.65 BSC 0.322 7.40 0.037 0.55 28 0o - 0.95 6 28 8o 0o - 8.20 7 8o Rev. 1 3/95 ICL3244 Small Outline Plastic Packages (SOIC) M28.3 (JEDEC MS-013-AE ISSUE C) 28 LEAD WIDE BODY SMALL OUTLINE PLASTIC PACKAGE N INDEX AREA H 0.25(0.010) M B M INCHES E SYMBOL -B- 1 2 3 L SEATING PLANE -A- h x 45o A D -C- e A1 B 0.25(0.010) M C 0.10(0.004) C A M B S MILLIMETERS MIN MAX NOTES A 0.0926 0.1043 2.35 2.65 - 0.0040 0.0118 0.10 0.30 - B 0.013 0.0200 0.33 0.51 9 C 0.0091 0.0125 0.23 0.32 - D 0.6969 0.7125 17.70 18.10 3 E 0.2914 0.2992 7.40 7.60 4 0.05 BSC 1.27 BSC - H 0.394 0.419 10.00 10.65 - h 0.01 0.029 0.25 0.75 5 L 0.016 0.050 0.40 1.27 6 8o 0o N NOTES: 1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of Publication Number 95. 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 0.15mm (0.006 inch) per side. 4. Dimension “E” does not include interlead flash or protrusions. Interlead flash and protrusions shall not exceed 0.25mm (0.010 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. The lead width “B”, as measured 0.36mm (0.014 inch) or greater above the seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch) 10. Controlling dimension: MILLIMETER. Converted inch dimensions are not necessarily exact. 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