ISL83387E ® Data Sheet FN6040 February 2003 +/-15kV ESD Protected, +3V to +5.5V, 1Microamp, 250kbps, RS-232 Transceivers with Enhanced Automatic Powerdown and a Separate Logic Supply The Intersil ISL83387E is a 3.0V to 5.5V powered RS-232 transceiver which meets ElA/TIA-232 and V.28/V.24 specifications, even at VCC = 3.0V. Additionally, 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 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. TSSOP 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. The ISL83387E features a V L pin that adjusts the logic pin output levels and input thresholds to values compatible with the VCC powering the external logic (e.g., a UART). This device includes 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 30 seconds. It power back up, automatically, whenever it senses a transition on any transmitter or receiver input. Features • VL Supply Pin for Compatibility with Mixed Voltage Systems • ESD Protection for RS-232 I/O Pins to ±15kV (IEC61000) • Low Power, Pin Compatible Upgrade for MAX3387E • Manual and Enhanced Automatic Powerdown Features • Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V • On-Chip Charge Pumps Require Only Four External 0.1µF Capacitors • Receivers Stay Active in Powerdown • Very Low Supply Current . . . . . . . . . . . . . . . . . . . . 300µA • Guaranteed Minimum Data Rate . . . . . . . . . . . . . 250kbps • 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 - Digital Cameras - PDA’s and PDA Cradles - Cellular/Mobile Phones Table 1 summarizes the features of the ISL83387E, while Application Note AN9863 summarizes the features of each device comprising the 3V RS-232 family. Ordering Information PART NO. (BRAND) TEMP. RANGE ( oC) PACKAGE PKG. NO. ISL83387EIV (83387EIV) -40 to 85 24 Ld TSSOP M24.173 ISL83387EIV-T (83387EIV) -40 to 85 Tape and Reel M24.173 TABLE 1. SUMMARY OF FEATURES PART NUMBER ISL83387E NO. OF NO. OF DATA RATE Rx. ENABLE Tx. Rx. (kbps) FUNCTION? 3 3 250 1 NO VL LOGIC SUPPLY PIN? YES MANUAL ENHANCED AUTOMATIC POWER- DOWN? POWERDOWN FUNCTION? 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 registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2003. All Rights Reserved ISL83387E Pinout ISL83387E (TSSOP) TOP VIEW C1+ 1 24 FORCEOFF V+ 2 23 VCC 3 22 GND C1- C2+ 4 21 T1 OUT C2- 5 20 T2 OUT V- 6 19 T3 OUT T1IN 7 18 R1IN T2IN 8 17 R2IN INVALID 9 16 R3IN 15 VL T3IN 10 FORCEON 11 14 R1OUT R3OUT 12 13 R2OUT 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. The switching point is a function of the VL voltage. TOUT RIN ROUT VL INVALID ±15kV ESD Protected , RS-232 level (nominally ±5.5V) transmitter outputs. ±15kV ESD Protected , RS-232 compatible receiver inputs. TTL/CMOS level receiver outputs. Swings between GND and VL. Logic-Level Supply. All TTL/CMOS inputs and outputs are powered by this supply. Active low output that indicates if no valid RS-232 levels are present on any receiver input. Swings between GND and VL. FORCEOFF Active low to shut down transmitters and on-chip power supply. This overrides any automatic circuitry and FORCEON (see Table 2). The switching point is a function of the VL voltage. FORCEON Active high input to override automatic powerdown circuitry thereby keeping transmitters active. (FORCEOFF must be high). The switching point is a function of the VL voltage. 2 ISL83387E Typical Operating Circuit +3.3V + 0.1µF 1 C1 0.1µF + C2 0.1µF C14 C2+ + 5 C2- 23 C1+ VCC 3 V+ VT1 7 T2 20 T2IN T3 10 19 T3IN TTL/CMOS LOGIC LEVELS R1 14 6 21 T1IN 8 2 18 R1OUT + C3 0.1µF C4 0.1µF + T1OUT T2OUT RS-232 LEVELS T3OUT R1IN 5kΩ R2 13 17 R2OUT R2IN 5kΩ R3 12 16 R3OUT R3IN 5kΩ LOGIC VCC 0.1µF 15 VL + 11 FORCEON VCC TO POWER CONTROL LOGIC 24 FORCEOFF 9 INVALID GND 22 3 RS-232 LEVELS ISL83387E Absolute Maximum Ratings Thermal Information VCC to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V VL to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V V- to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V Input Voltages TIN, FORCEON, FORCEOFF . . . . . . . . . . . . . . . . . . -0.3V to 6V RIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±25V Output Voltages TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±13.2V ROUT, INVALID . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VL +0.3V) Short Circuit Duration TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table Thermal Resistance (Typical, Note 1) θJA (oC/W) 24 Ld TSSOP Package . . . . . . . . . . . . . . . . . . . . . . 140 Moisture Sensitivity (see Technical Brief TB363) TSSOP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1 Maximum Junction Temperature (Plastic Package) . . . . . . . 150oC Maximum Storage Temperature Range . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC (Lead Tips Only) Operating Conditions Temperature Range ISL83387EIV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to 85oC 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 a low effective thermal conductivity test board in free air. See Tech Brief TB379 for details. Test Conditions: VCC = 3V to 5.5V, C1 - C 4 = 0.1 µF, VL = VCC; Unless Otherwise Specified. Typicals are at TA = 25oC, VCC = VL = 3.3V Electrical Specifications PARAMETER TEST CONDITIONS TEMP (oC) MIN TYP MAX UNITS DC CHARACTERISTICS Supply Current, Automatic Powerdown All R IN Open, FORCEON = GND, FORCEOFF = VCC 25 - 1 10 µA Supply Current, Powerdown FORCEOFF = GND 25 - 1 10 µA Supply Current, Automatic Powerdown Disabled All Outputs Unloaded, FORCEON = FORCEOFF = VCC, VCC = 3.15V 25 - 0.3 1 mA LOGIC AND TRANSMITTER INPUTS Input Logic Threshold Low TIN, FORCEON, FORCEOFF Input Logic Threshold High TIN, FORCEON, FORCEOFF VL = 3.3V or 5V Full - - 0.8 V VL = 2.5V Full - - 0.6 V VL = 5V Full 2.4 - - V VL = 3.3V Full 2.0 - - V VL = 2.5V Full 1.4 - - V VL = 1.8V 25 - 0.9 - V 25 - 0.5 - V TIN, FORCEON, FORCEOFF Full - ±0.01 ±1.0 µA Output Voltage Low IOUT = 1.6mA Full - - 0.4 V Output Voltage High IOUT = -1.0mA Full VL - 0.6 VL - 0.1 - V Full -25 - 25 V VCC = VL = 5.0V 25 0.8 1.5 - V VCC = VL = 3.3V 25 0.6 1.2 - V VCC = VL = 5.0V 25 - 1.8 2.4 V VCC = VL = 3.3V Transmitter Input Hysteresis Input Leakage Current RECEIVER OUTPUTS RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High 25 - 1.5 2.4 V Input Hysteresis 25 - 0.5 - V Input Resistance 25 3 5 7 kΩ 4 ISL83387E Test Conditions: VCC = 3V to 5.5V, C1 - C 4 = 0.1 µF, VL = VCC; Unless Otherwise Specified. Typicals are at TA = 25oC, VCC = VL = 3.3V (Continued) Electrical Specifications PARAMETER TEST CONDITIONS TEMP (oC) MIN TYP MAX UNITS - V TRANSMITTER OUTPUTS Output Voltage Swing All Transmitter Outputs Loaded with 3kΩ to Ground Full ±5.0 ±5.4 Output Resistance VCC = V+ = V- = 0V, Transmitter Output = ±2V Full 300 10M - Ω Output Short-Circuit Current VOUT = 0V Full - ±35 ±60 mA Output Leakage Current VOUT = ±12V, VCC = 0V or 3V to 5.5V Automatic Powerdown or FORCEOFF = GND Full - - ±25 µA ENHANCED AUTOMATIC POWERDOWN (FORCEON = GND, FORCEOFF = V CC) Receiver Input Thresholds to INVALID High See Figure 4 Full -2.7 - 2.7 V Receiver Input Thresholds to INVALID Low See Figure 4 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 VL - 0.6 - - V Receiver Positive or Negative See Figure 7 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 Note 2, See Figure 7 Transmitters Enabled Delay (tWU) 25 - 100 - µs Note 2, See Figure 7 Full 15 30 60 sec 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 Receiver or Transmitter Edge to Transmitters Disabled Delay (tAUTOPWDN) See Figure 7 TIMING CHARACTERISTICS Time to Exit Powerdown TX | VOUT | ≥ 3.7V 25 - 100 - µs 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 18 30 V/µs CL = 150pF to 2500pF 25 4 13 30 V/µs Human Body Model 25 - ±15 - kV IEC61000-4-2 Air Gap Discharge 25 - ±15 - kV IEC61000-4-2 Contact Discharge 25 - ±8 - kV ESD PERFORMANCE RS-232 Pins (T OUT, R IN) NOTE: 2. An “edge” is defined as a transition through the transmitter or receiver input thresholds. 5 ISL83387E Detailed Description The ISL83387E operates from a single +3V to +5.5V supply, guarantees a 250kbps minimum data rate, requires only four small external 0.1µF capacitors, features low power consumption, and meets 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 from GND to V L, and do not tristate in powerdown (see Table 2). VL RXIN -25V ≤ VRIN ≤ +25V RXOUT 5kΩ GND ≤ VROUT ≤ VL GND FIGURE 1. RECEIVER CONNECTIONS Intersil’s new ISL83387E 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 over the full VCC range; other capacitor combinations can be used as shown in Table 3. The charge pumps operate discontinuously (i.e., they turn off as soon as the V+ and V- supplies are pumped up to the nominal values), resulting in significant power savings. Transmitters The transmitters are proprietary, low dropout, inverting drivers that translate TTL/CMOS inputs to EIA/TIA-232 output levels. Coupled with the on-chip ±5.5V supplies, these transmitters deliver true RS-232 levels over a wide range of single supply system voltages. All transmitter outputs disable and assume a high impedance state when the device enters the 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), V CC ≥ 3.0V, with one transmitter operating at full speed. Under more typical conditions of V CC ≥ 3.3V, R L = 3kΩ, and CL = 250pF, one transmitter easily operates at 1.25Mbps. The transmitter input threshold is set by the voltage applied to the VL supply pin. Transmitter inputs float if left unconnected (there are no pull-up resistors), and may cause ICC increases. Connect unused inputs to GND for the best performance. Low Power Operation This 3V device requires a nominal supply current of 0.3mA, even at V CC = 5.5V, during normal operation (not in powerdown mode). This is considerably less than the 11mA current required by comparable 5V RS-232 devices, allowing users to reduce system power simply by replacing the old style device with the ISL83387E in new designs. Powerdown Functionality 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 V CC, V- collapses to GND), and the transmitter outputs tristate. This micro-power mode makes these devices ideal for battery powered and portable applications. Software Controlled (Manual) Powerdown This device 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. Connecting FORCEOFF and FORCEON together disables the enhanced automatic powerdown feature, enabling them to function as a manual SHUTDOWN input (see Figure 2). With any of the above control schemes, the time required to exit powerdown, and resume transmission is only 100µs. Receivers The ISL83387E contains standard inverting receivers that 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. Receiver outputs swing 6 When using both manual and enhanced automatic powerdown (FORCEON = 0), the ISL83387E 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 3 illustrates a circuit for ensuring that the ISL83387E powers up as soon as FORCEOFF switches high. The rising edge of the Master Powerdown signal forces the device to power up, and the ISL83387E returns to enhanced automatic powerdown ISL83387E TABLE 2. POWERDOWN LOGIC TRUTH TABLE RCVR OR XMTR EDGE WITHIN 30 SEC? RS-232 LEVEL PRESENT AT INVALID FORCEOFF FORCEON TRANSMITTER RECEIVER INPUT INPUT OUTPUTS OUTPUTS RECEIVER INPUT? OUTPUT NO H H Active Active NO L NO H H Active Active YES H YES H L Active Active NO L YES H L Active Active YES H NO H L High-Z Active NO L NO H L High-Z Active YES H X L X High-Z Active NO L X L X High-Z Active YES H MODE OF OPERATION Normal Operation (Enhanced Auto Powerdown Disabled) Normal Operation (Enhanced Auto Powerdown Enabled) Powerdown Due to Enhanced Auto Powerdown Logic Manual Powerdown INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWERDOWN) X NOTE 3 NOTE 3 Active Active YES H Normal Operation X NOTE 3 NOTE 3 High-Z Active NO L Forced Auto Powerdown NOTES: 3. Input is connected to INVALID Output. FORCEOFF, FORCEON PWR MGT LOGIC INVALID POWER MANAGEMENT UNIT MASTER POWERDOWN LINE 0.1µF 1MΩ I/O CHIP POWER SUPPLY FORCEOFF VL FORCEON ISL83387E ISL83387E VCC FIGURE 3. CIRCUIT TO ENSURE IMMEDIATE POWER UP WHEN EXITING FORCED POWERDOWN CPU VL Logic Supply Input I/O UART FIGURE 2. CONNECTIONS FOR MANUAL POWERDOWN mode an RC time constant after this rising edge. The time constant isn’t critical, because the ISL83387E remains powered up for 30 seconds after the FORCEON falling edge, even if there are no signal transitions. This gives slowto-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. Unlike other RS-232 interface devices where the CMOS outputs swing between 0 and V CC, the ISL83387E features a separate logic supply input (V L; 1.8V to 5V, regardless of VCC ) that sets VOH for the receiver and INVALID outputs. Connecting VL to a host logic supply lower than VCC , prevents the ISL83387E outputs from forward biasing the input diodes of a logic device powered by that lower supply. Connecting VL to a logic supply greater than V CC ensures that the receiver and INVALID output levels are compatible even with the CMOS input V IH of AC, HC, and CD4000 devices. Note that the V L supply current increases to 100µA with VL = 5V and V CC = 3.3V (see Figure 16). VL also powers the transmitter and logic inputs, thereby setting their switching thresholds to levels compatible with the logic supply. This separate logic supply pin allows a great deal of flexibility in interfacing to systems with different logic supplies. If logic translation isn’t required, connect VL to the ISL83387E VCC. INVALID Output The INVALID output always indicates (see Table 2) whether or not 30µs have elapsed with invalid RS-232 signals (see 7 ISL83387E Figures 4 and 7) persisting on all of the receiver inputs, 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 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). 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 5 illustrates the enhanced powerdown control logic. Note that once the ISL83387E enters powerdown (manually or automatically), the 30 second timer remains timed out (set), keeping the ISL83387E powered down until FORCEON transitions high, or until a transition occurs on a receiver or transmitter input. As stated previously, the INVALID output switches low whenever invalid levels have persisted on all of the receiver inputs for more than 30µs (see Figure 7), but this has no direct effect on the state of the ISL83387E (see the next sections for methods of utilizing INVALID to power down the device). The time to recover from automatic powerdown mode is typically 100µs. FORCEOFF T_IN EDGE DETECT S 30s TIMER R_IN AUTOPWDN R EDGE DETECT VALID RS-232 LEVEL - INVALID = 1 2.7V INDETERMINATE FORCEON FIGURE 5. ENHANCED AUTOMATIC POWERDOWN LOGIC 0.3V INVALID LEVEL - INVALID = 0 Emulating Standard Automatic Powerdown -2.7V VALID RS-232 LEVEL - INVALID = 1 If enhanced automatic powerdown isn’t desired, the user can implement the standard automatic powerdown feature (mimics the function on the ICL3221E/23E/43E) by connecting the INVALID output to the FORCEON and FORCEOFF inputs, as shown in Figure 6. After 30µs of INVALID FIGURE 4. DEFINITION OF VALID RS-232 RECEIVER LEVELS Enhanced Automatic Powerdown Even greater power savings is available by using the 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 ISL83387E 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. 8 FORCEOFF INDETERMINATE FORCEON -0.3V ISL83387E I/O UART CPU FIGURE 6. CONNECTIONS FOR AUTOMATIC POWERDOWN WHEN NO VALID RECEIVER SIGNALS ARE PRESENT invalid receiver levels, INVALID switches low and drives the ISL83387E into a forced powerdown condition. INVALID switches high as soon as a receiver input senses a valid ISL83387E RECEIVER INPUTS } INVALID REGION TRANSMITTER INPUTS TRANSMITTER OUTPUTS tINVH INVALID OUTPUT tINVL tAUTOPWDN tAUTOPWDN tWU tWU V+ VCC 0 V- FIGURE 7. ENHANCED AUTOMATIC POWERDOWN AND INVALID TIMING DIAGRAMS RS-232 level, forcing the ISL83387E 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. Hybrid Automatic Powerdown Options 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 RS-232 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 ISL83387E remains powered down until the cable is reconnected (INVALID = FORCEOFF = 1) and a transition occurs on a receiver or transmitter input (see Figure 5). For immediate power up when the cable is reattached, connect FORCEON to FORCEOFF through a network similar to that shown in Figure 3. Capacitor Selection The ISL83387E charge pumps require only 0.1µF capacitors for the full operational voltage range. Table 3 lists other acceptable capacitor values for various supply voltage ranges. Do not use values smaller than those listed in Table 3. Increasing the capacitor values (by a factor of 2) 9 reduces ripple on the transmitter outputs and slightly reduces power consumption. TABLE 3. REQUIRED CAPACITOR VALUES VCC (V) C1 (µF) C2, C 3, 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 0.22 1 When using minimum required capacitor values, make sure that capacitor values do not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor’s equivalent series resistance (ESR) usually rises at low temperatures and it influences the amount of ripple on V+ and V-. Power Supply Decoupling In most circumstances a 0.1µF bypass capacitor is adequate. In applications that are particularly sensitive to power supply noise, decouple VCC to ground with a capacitor of the same value as the charge-pump capacitor C 1. Connect the bypass capacitor as close as possible to the IC. Transmitter Outputs when Exiting Powerdown Figure 8 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. ISL83387E 5V/DIV 5V/DIV. FORCEOFF T1 2V/DIV T1IN T1OUT T2 R1OUT VCC = +3.3V C1 - C4 = 0.1µF VCC = +3.3V C1 - C4 = 0.1µF TIME (20µs/DIV.) 5µs/DIV. FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING POWERDOWN High Data Rates The ISL83387E maintains the RS-232 ±5V minimum transmitter output voltages even at high data rates. Figure 9 details a transmitter loopback test circuit, and Figure 10 illustrates the loopback test result at 120kbps. For this test, all transmitters were simultaneously driving RS-232 loads in parallel with 1000pF, at 120kbps. Figure 11 shows the loopback results for a single transmitter driving 1000pF and an RS-232 load at 250kbps. The static transmitters were also loaded with an RS-232 receiver. FIGURE 10. LOOPBACK TEST AT 120kbps 5V/DIV. T1IN T1OUT R1OUT VCC VCC = +3.3V C1 - C4 = 0.1µF + 0.1µF 2µs/DIV. + VCC C1+ VL V+ C1 C1- FIGURE 11. LOOPBACK TEST AT 250kbps + C3 Interconnection with 3V and 5V Logic ISL83387E + V- C2+ C2 C4 + C2TIN TOUT RIN ROUT FORCEON VCC 1000pF 5K FORCEOFF Standard 3.3V powered RS-232 devices interface well with 3V and 5V powered TTL compatible logic families (e.g., ACT and HCT), but the logic outputs (e.g., R OUTS ) fail to reach the V IH level of 5V powered CMOS families like HC, AC, and CD4000. The ISL83387E V L supply pin solves this problem. By connecting V L to the same supply (1.8V to 5V) powering the logic device, the ISL83387E logic outputs will swing from GND to the logic V CC . ±15kV ESD Protection FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT 10 All pins on the 3V interface devices include ESD protection structures, but the ISL83387E incorporates advanced structures which 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. Simply touching the port pins, or connecting a cable, can cause an ESD event that might destroy unprotected ICs. These new ESD structures protect the device whether or not it is powered up, protect ISL83387E without allowing any latchup mechanism to activate, and don’t interfere with RS-232 signals as large as ±25V. Human Body Model (HBM) Testing As the name implies, this test method emulates the ESD event delivered to an IC during human handling. The tester delivers the charge through a 1.5kΩ current limiting resistor, making the test less severe than the IEC61000 test which utilizes a 330Ω limiting resistor. The HBM method determines an ICs ability to withstand the ESD transients typically present during handling and manufacturing. Due to the random nature of these events, each pin is tested with respect to all other pins. The RS-232 pins on “E” family devices can withstand HBM ESD events to ±15kV. 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 Typical Performance Curves resistor coupled with the larger charge storage capacitor yields a test that is much more severe than the HBM test. The extra ESD protection built into this device’s RS-232 pins allows the design of equipment meeting level 4 criteria without the need for additional board level protection on the RS-232 port. AIR-GAP DISCHARGE TEST METHOD For this test method, a charged probe tip moves toward the IC pin until the voltage arcs to it. The current waveform delivered to the IC pin depends on approach speed, humidity, temperature, etc., so it is difficult to obtain repeatable results. The “E” device RS-232 pins withstand ±15kV air-gap discharges. CONTACT DISCHARGE TEST METHOD During the contact discharge test, the probe contacts the tested pin before the probe tip is energized, thereby eliminating the variables associated with the air-gap discharge. The result is a more repeatable and predictable test, but equipment limits prevent testing devices at voltages higher than ±8kV. All “E” family devices survive ±8kV contact discharges on the RS-232 pins. VCC = V L = 3.3V, T A = 25oC 30 VOUT+ 4.0 25 SLEW RATE (V/µs) TRANSMITTER OUTPUT VOLTAGE (V) 6.0 2.0 1 TRANSMITTER AT 250kbps OTHER TRANSMITTERS AT 30kbps 0 -2.0 -6.0 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) FIGURE 12. TRANSMITTER OUTPUT VOLTAGE vs LOAD CAPACITANCE 11 +SLEW 15 -SLEW 10 VOUT - -4.0 20 5 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) FIGURE 13. SLEW RATE vs LOAD CAPACITANCE 5000 ISL83387E Typical Performance Curves VCC = V L = 3.3V, T A = 25oC (Continued) 45 3.5 40 250kbps 35 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) NO LOAD ALL OUTPUTS STATIC 3.0 30 120kbps 25 20 20kbps 15 2.5 2.0 1.5 1.0 0.5 10 0 2000 1000 4000 3000 0 2.5 5000 3.0 3.5 4.0 10m NO LOAD ALL OUTPUTS STATIC VCC = 3.3V 100µ IL (A) 10µ VL ≤ VCC VL > VCC 1µ 100n 10n 1n 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 VL (V) FIGURE 16. VL SUPPLY CURRENT vs VL VOLTAGE Die Characteristics SUBSTRATE POTENTIAL (POWERED UP) GND TRANSISTOR COUNT ISL83387E: 1063 PROCESS Si Gate CMOS 12 5.0 5.5 FIGURE 15. SUPPLY CURRENT vs SUPPLY VOLTAGE FIGURE 14. SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA 1m 4.5 SUPPLY VOLTAGE (V) LOAD CAPACITANCE (pF) 7.0 6.0 ISL83387E Thin Shrink Small Outline Plastic Packages (TSSOP) N INDEX AREA E 0.25(0.010) M 2 24 LEAD THIN SHRINK SMALL OUTLINE PLASTIC PACKAGE E1 GAUGE PLANE -B1 M24.173 B M INCHES SYMBOL 3 L 0.05(0.002) -A- 0.25 0.010 SEATING PLANE A D -C- α e A2 A1 b c 0.10(0.004) 0.10(0.004) M C A M B S NOTES: MIN MAX MIN MAX NOTES A - 0.047 - 1.20 - A1 0.002 0.006 0.05 0.15 - A2 0.031 0.051 0.80 1.05 - b 0.0075 0.0118 0.19 0.30 9 c 0.0035 0.0079 0.09 0.20 - D 0.303 0.311 7.70 7.90 3 E1 0.169 0.177 4.30 4.50 4 e 0.026 BSC 0.65 BSC - E 0.246 0.256 6.25 6.50 - L 0.0177 0.0295 0.45 0.75 6 8o 0o N 1. These package dimensions are within allowable dimensions of JEDEC MO-153-AD, Issue E. MILLIMETERS α 24 0o 24 7 8o 2. Dimensioning and tolerancing per ANSI Y14.5M-1982. Rev. 0 6/98 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 “E1” does not include interlead flash or protrusions. Interlead flash and protrusions shall not exceed 0.15mm (0.006 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 0.08mm (0.003 inch) total in excess of “b” dimension at maximum material condition. Minimum space between protrusion and adjacent lead is 0.07mm (0.0027 inch). 10. Controlling dimension: MILLIMETER. Converted inch dimensions are not necessarily exact. (Angles in degrees) All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 13