SP3238EEA

SP3238E SIGNAL PROCESSING EXCELLENCE Intelligent +3.0V to +5.5V RS-232 Transceivers s Meets true EIA/TIA-232-F Standards from a +3.0V to +5.5V power supply s Interoperable with EIA/TIA-232 and adheres to EIA/TIA-562 down to a +2.7V power source s Auto-Online™ circuitry automatically wakes up from a 1µA shutdown s Minimum 250Kbps data rate under load s Regulated Charge Pump Yields Stable RS-232 Outputs Regardless of VCC Variations s Enhanced ESD Specifications: +15KV Human Body Model +15KV IEC1000-4-2 Air Discharge +8KV IEC1000-4-2 Contact Discharge DESCRIPTION The SP3238E device is an RS-232 transceiver solution intended for portable or hand-held applications such as notebook and palmtop computers. The SP3238E uses an internal high-efficiency, charge-pump power supply that requires only 0.1µF capacitors in 3.3V operation. This charge pump and Sipex's driver architecture allow the SP3238E device to deliver compliant RS-232 performance from a single power supply ranging from +3.0V to +5.0V. The SP3238E is a 5-driver/3-receiver device, ideal for laptop/notebook computer and PDA applications. The SP3238E includes one complementary receiver that remains alert to monitor an external device's Ring Indicate signal while the device is shutdown. The Auto-Online feature allows the device to automatically "wake-up" during a shutdown state when an RS-232 cable is connected and a connected peripheral is turned on. Otherwise, the device automatically shuts itself down drawing less than 1µA. SELECTION TABLE Device SP3221E SP3223E SP3243E SP3238E Power Supplies +3.0V to +5.5V +3.0V to +5.5V +3.0V to +5.5V +3.0V to +5.5V RS-232 Drivers 1 2 3 5 RS-232 Receivers 1 2 5 3 External Components 4 capacitors 4 capacitors 4 capacitors 4 capacitors Auto-Online Circuitry YES YES YES YES TTL 3-State YES YES YES YES No. of Pins 16 20 28 28 Applicable U.S. Patents - 5,306,954; and other patents pending. SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 1 ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability and cause permanent damage to the device. VCC.......................................................-0.3V to +6.0V V+ (NOTE 1).......................................-0.3V to +7.0V V- (NOTE 1)........................................+0.3V to -7.0V V+ + |V-| (NOTE 1)...........................................+13V ICC (DC VCC or GND current).........................+100mA Input Voltages TxIN, ONLINE, SHUTDOWN, EN ...............................-0.3V to +6.0V RxIN...................................................................+15V Output Voltages TxOUT...............................................................+15V RxOUT, STATUS.......................-0.3V to (VCC + 0.3V) Short-Circuit Duration TxOUT.....................................................Continuous Storage Temperature......................-65°C to +150°C Power Dissipation per package 28-pin SSOP (derate 11.2mW/oC above +70oC).......900mW 28-pin TSSOP (derate 13.2mW/oC above +70oC)...1100mW NOTE 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 15V. SPECIFICATIONS Unless otherwise noted, the following specifications apply for VCC = +3.0V to +5.5V with TAMB = TMIN to TMAX. Typical values apply at VCC = +3.3V or +5.0V and TAMB = 25°C. PARAMETER DC CHARACTERISTICS Supply Current, Auto-Online Supply Current, Shutdown Supply Current, Auto-Online Disabled MIN. TYP. MAX. UNITS µA µA mA CONDITIONS 1.0 1.0 0.4 10 10 2.0 All RxIN open, ONLINE = GND, SHUTDOWN = VCC SHUTDOWN = GND ONLINE = SHUTDOWN = VCC, no load LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshold LOW HIGH Input Leakage Current Output Leakage Current Output Voltage LOW Output Voltage HIGH VCC - 0.6 VCC-0.1 0.8 2.4 +0.01 +0.05 +1.0 +10 0.4 µA µA V V TxIN, ONLINE, SHUTDOWN TAMB = 25OC Receivers Disabled IOUT = 1.6mA IOUT = 1.0mA V VCC = +3.3V or +5.0V, TxIN ONLINE, SHUTDOWN SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 2 Unless otherwise noted, the following specifications apply for VCC = +3.0V to +5.5V with TAMB = TMIN to TMAX. Typical values apply at VCC = +3.3V or +5.0V and TAMB = 25°C. SPECIFICATIONS (continued) PARAMETER DRIVER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current RECEIVER INPUTS Input Voltage Range Input Threshold LOW Input Threshold LOW Input Threshold HIGH Input Threshold HIGH Input Hysteresis Input Resistance MIN. TYP. MAX. UNITS CONDITIONS ±5.0 300 ±5.4 V Ω All driver outputs loaded with 3KΩ to GND VCC = V+ = V- = 0V, VOUT = ±2V VOUT = GND VOUT = ±15V VCC = 0V or 3.0V to 5.5V, VOUT = ±15V, Drivers disabled ±35 ±70 ±100 TBD ±25 mA µA -15 0.6 0.8 1.2 1.5 1.5 1.8 0.3 3 5 15 V V V VCC = 3.3V VCC = 5.0V VCC = 3.3V VCC = 5.0V 2.4 2.4 V V V 7 kΩ Auto-Online CIRCUITRY CHARACTERISTICS (ONLINE = GND, SHUTDOWN = VCC) 0.4 VCC - 0.6 200 0.5 V V µS µS IOUT = 1.6mA IOUT = -1.0mA STATUS Output Voltage LOW STATUS Output Voltage HIGH Receiver Threshold to Drivers Enabled (tONLINE) Receiver Positive or Negative Threshold to STATUS HIGH (tSTSH) Receiver Positive or Negative Threshold to STATUS LOW (tSTSL) Figure 15 Figure 15 20 µS Figure 15 SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 3 SPECIFICATIONS (continued) Unless otherwise noted, the following specifications apply for VCC = +3.0V to +5.5V with TAMB = TMIN to TMAX. Typical values apply at VCC = +3.3V or +5.0V and TAMB = 25°C. PARAMETER TIMING CHARACTERISTICS Maximum Data Rate Receiver Propagation Delay tPHL tPLH Receiver Output Enable Time Receiver Output Disable Time Driver Skew Receiver Skew Transition-Region Slew Rate 250 kbps µs ns ns 500 1000 30 ns ns V/µs RL = 3kΩ, CL = 1000pF, one driver active Receiver input to Receiver output, CL = 150pF Normal operation Normal operation | tPHL - tPLH |, TAMB = 25oC | tPHL - tPLH | VCC= 3.3V, RL = 3kΩ, TAMB = 25oC, measurements taken from -3.0V to +3.0V or +3.0V to -3.0V MIN. TYP. MAX. UNITS CONDITIONS 0.15 0.15 200 200 100 200 TYPICAL PERFORMANCE CHARACTERISTICS Unless otherwise noted, the following performance characteristics apply for VCC = +3.3V, 235Kbps data rate, all drivers loaded with 3kΩ, 0.1µF charge pump capacitors, and TAMB = +25°C. 14 6 12 10 Transmitter Output Voltage [V] 4 2 0 0 -2 -4 -6 Load Capacitance [pF] 500 1000 1500 Vout+ VoutSlew Rate [V/µs] 8 6 4 2 0 0 500 1000 1500 Load Capacitance [pF] 2000 +Slew -Slew Figure 1. Transmitter Output Voltage VS. Load Capacitance Figure 2. Slew Rate VS. Load Capacitance SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 4 NAME C2+ GND C2VT1OUT T2OUT T3OUT R1IN R2IN T4OUT R3IN T5OUT ONLINE SHUTDOWN STATUS R1OUT T5IN R3OUT T4IN R2OUT R1OUT T3IN T2IN T1IN C1VCC V+ C1+ FUNCTION Positive terminal of the inverting charge-pump capacitor. Ground. Negative terminal of the inverting charge-pump capacitor. Regulated -5.5V output generated by the charge pump. RS-232 driver output. RS-232 driver output. RS-232 driver output. RS-232 receiver input. RS-232 receiver input. RS-232 driver output. RS-232 receiver input. RS-232 driver output. Apply logic HIGH to override Auto-Online circuitry keeping drivers active (SHUTDOWN must also be logic HIGH, refer to Table 2). Apply logic LOW to shut down drivers and charge pump. This overrides all AutoOnline circuitry and ONLINE (refer to Table 2). TTL/CMOS Output indicating online and shutdown status. Non-inverting receiver-1 output, active in shutdown. TTL/CMOS driver input. TTL/CMOS receiver output. TTL/CMOS driver input. TTL/CMOS receiver output. TTL/CMOS receiver output. TTL/CMOS driver input. TTL/CMOS driver input. TTL/CMOS driver input. Negative terminal of the voltage doubler charge-pump capacitor. +3.0V to +5.5V supply voltage. Regulated +5.5V output generated by the charge pump. Positive terminal of the voltage doubler charge-pump capacitor. PIN NO. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Table 1. Device Pin Description SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 5 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unless otherwise noted, the following performance characteristics apply for VCC = +3.3V, 235kbps data rate, all drivers loaded with 3kΩ, 0.1µF charge pump capacitors, and TAMB = +25°C. 40 35 30 25 20 15 10 5 0 0 500 1000 1500 Load Capacitance [pF] 2000 118KHz 60KHz 10KHz Figure 3. Supply Current VS. Load Capacitance when Transmitting Data Supply Current [mA] C2+ 1 GND 2 C2- 3 V- 4 T1OUT 5 T2OUT 6 T3OUT 7 R1IN 8 R2IN 9 T4OUT 10 R3IN 11 T5OUT 12 ONLINE 13 SHUTDOWN 14 SP3238E 28 C1+ 27 26 25 V+ VCC C1- 24 T1IN 23 T2IN 22 T3IN 21 R1OUT 20 R2OUT 19 T4IN 18 17 16 R3OUT T5IN R1OUT 15 STATUS Figure 4. SP3238E Pinout Configuration SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 6 C5 + VCC 0.1µF 28 C1+ 0.1µF 25 C11 C2+ 26 VCC V+ 27 C3 + 0.1µF C1 + SP3238E C2 + V- 4 C4 + 0.1µF 0.1µF 3 C224 T1IN 23 T2IN T1OUT 5 T2OUT 6 T3OUT 7 T4OUT 10 T5OUT 12 TTL/CMOS INPUTS 22 T3IN 19 T4IN 17 T5IN 16 R1OUT 21 R1OUT RS-232 OUTPUTS R1IN 8 9 11 RS-232 INPUTS TTL/CMOS OUTPUTS 5kΩ 20 R2OUT 5kΩ 18 R3OUT VCC R2IN R3IN 5kΩ 14 13 SHUTDOWN ONLINE To µP Supervisor Circuit 15 STATUS GND 2 Figure 5. SP3238E Typical Operating Circuit SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 7 DESCRIPTION The SP3238E device meets the EIA/TIA-232 and ITU-T V.28/V.24 communication protocols and can be implemented in battery-powered, portable, or hand-held applications such as notebook or palmtop computers. The SP3238E device features Sipex's proprietary and patented (U.S.-- 5,306,954) on-board charge pump circuitry that generates ±5.5V RS-232 voltage levels from a single +3.0V to +5.5V power supply. The SP3238E device can operate at a typical data rate of 250kbps fully loaded. The SP3238E is a 5-driver/3-receiver device, ideal for portable or hand-held applications. The SP3238E includes one complementary always-active receiver that can monitor an external device (such as a modem) in shutdown. This aids in protecting the UART or serial controller IC by preventing forward biasing of the protection diodes where VCC may be disconnected. The SP3238E device is an ideal choice for power sensitive designs. The SP3238E device features Auto-Online circuitry which reduces the power supply drain to a 1µA supply current. In many portable or hand-held applications, an RS-232 cable can be disconnected or a connected peripheral can be turned off. Under these conditions, the internal charge pump and the drivers will be shut down. Otherwise, the system automatically comes online. This feature allows design engineers to address power saving concerns without major design changes. THEORY OF OPERATION The SP3238E device is made up of four basic circuit blocks: 1. Drivers, 2. Receivers, 3. the Sipex proprietary charge pump, and 4. Auto-Online circuitry. Drivers The drivers are inverting level transmitters that convert TTL or CMOS logic levels to 5.0V EIA/ TIA-232 levels with an inverted sense relative to the input logic levels. Typically, the RS-232 output voltage swing is +5.4V with no load and +5V minimum fully loaded. The driver outputs are protected against infinite short-circuits to ground without degradation in reliability. These drivers comply with the EIA-TIA-232F and all previous RS-232 versions. The drivers typically can operate at a data rate of 250kbps. The drivers can guarantee a data rate of 120kbps fully loaded with 3k Ω in parallel with 1000pF, ensuring compatibility with PC-to-PC communication software. The slew rate of the driver output is internally limited to a maximum of 30V/µs in order to meet the EIA standards (EIA RS-232D 2.1.7, Paragraph 5). The transition of the loaded output from HIGH to LOW also meets the monotonicity requirements of the standard. VCC + 0.1µF 28 C1+ 0.1µF 25 C11 C2+ C2 + 0.1µF 3 C224 T1IN 23 T2IN 22 T3IN 19 T4IN 17 T5IN 16 R1OUT T1OUT 5 T2OUT 6 T3OUT 7 T4OUT 10 T5OUT 12 C5 26 VCC V+ 27 C3 + 0.1µF C1 + SP3238E V- 4 C4 + 0.1µF RxD CTS DSR DCD RI RS-232 OUTPUTS UART or Serial µC TxD RTS DTR VCC 21 R1OUT 5kΩ 20 R2OUT 5kΩ 18 R3OUT 5kΩ 14 13 15 SHUTDOWN ONLINE STATUS R1IN 8 R2IN 9 RS-232 INPUTS R3IN 11 GND 2 RESET µP Supervisor IC VIN Figure 6. Interface Circuitry Controlled by Microprocessor Supervisory Circuit SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 8 The SP3238E drivers can maintain high data rates up to 250kbps fully loaded. Figure 7 shows a loopback test circuit used to test the RS-232 Drivers. Figure 8 shows the test results of the loopback circuit with all three drivers active at 120kbps with typical RS-232 loads in parallel with 1000pF capacitors. Figure 9 shows the test results where one driver was active at 250kbps and all three drivers loaded with an RS-232 receiver in parallel with a 1000pF capacitor. A solid RS-232 data transmission rate of 120kbps provides compatibility with many designs in personal computer peripherals and LAN applications. Receivers The receivers convert ±5.0V EIA/TIA-232 levels to TTL or CMOS logic output levels. All receivers have an inverting output that can be disabled by using the EN pin. Receivers are active when the Auto-Online circuitry is enabled or when in shutdown. During the shutdown, the receivers will continue to be active. If there is no activity present at the receivers for a period longer than 100µs or when SHUTDOWN is enabled, the device goes into a standby mode where the circuit draws 1µA. The truth table logic of the driver and receiver outputs can be found in Table 2. VCC + 0.1µF C1+ 0.1µF C1C2+ C2 + 0.1µF C2LOGIC INPUTS LOGIC OUTPUTS VCC ONLINE SHUTDOWN GND TxIN TxOUT 1000pF C5 VCC V+ C3 + 0.1µF C1 + SP3238E VC4 + 0.1µF RxOUT 5kΩ RxIN Figure 7. Loopback Test Circuit for RS-232 Driver Data Transmission Rates The SP3238E includes an additional noninverting receiver with an output R1OUT. R1OUT is an extra output that remains active and monitors activity while the other receiver outputs are forced into high impedance. This allows Ring Indicator (RI) from a peripheral to be monitored without forward biasing the TTL/CMOS inputs of the other devices connected to the receiver outputs. TBD Figure 8. Loopback Test Circuit Result at 120kbps (All Drivers Fully Loaded) TBD Figure 9. Loopback Test Circuit result at 235kbps (All Drivers Fully Loaded) SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 9 Since receiver input is usually from a transmission line where long cable lengths and system interference can degrade the signal, the inputs have a typical hysteresis margin of 300mV. This ensures that the receiver is virtually immune to noisy transmission lines. Should an input be left unconnected, an internal 5kΩ pulldown resistor to ground will commit the output of the receiver to a HIGH state. Charge Pump The charge pump is a Sipex–patented design (U.S. 5,306,954) and uses a unique approach compared to older less–efficient designs. The charge pump still requires four external capacitors, but uses a four–phase voltage shifting technique to attain symmetrical 5.5V power supplies. The internal power supply consists of a regulated dual charge pump that provides output voltages 5.5V regardless of the input voltage (VCC) over the +3.0V to +5.5V range. This is important to maintain compliant RS-232 levels regardless of power supply fluctuations. The charge pump operates in a discontinuous mode using an internal oscillator. If the output voltages are less than a magnitude of 5.5V, the charge pump is enabled. If the output voltages exceed a magnitude of 5.5V, the charge pump is disabled. This oscillator controls the four phases of the voltage shifting. A description of each phase follows. Phase 1 — VSS charge storage — During this phase of the clock cycle, the positive side of capacitors C1 and C2 are initially charged to VCC. Cl+ is then switched to GND and the charge in C1– is transferred to C2–. Since C2+ is connected to VCC, the voltage potential across capacitor C2 is now 2 times VCC. Phase 2 — VSS transfer — Phase two of the clock connects the negative terminal of C2 to the VSS storage capacitor and the positive terminal of C2 to GND. This transfers a negative generated voltage to C 3 . This generated voltage is regulated to a minimum voltage of -5.5V. Simultaneous with the transfer of the voltage to C3, the positive side of capacitor C1 is switched to VCC and the negative side is connected to GND. Phase 3 — VDD charge storage — The third phase of the clock is identical to the first phase — the charge transferred in C1 produces –VCC in the negative terminal of C1, which is applied to the negative side of capacitor C2. Since C2+ is at VCC, the voltage potential across C2 is 2 times VCC. Phase 4 — VDD transfer — The fourth phase of the clock connects the negative terminal of C2 to GND, and transfers this positive generated voltage across C2 to C4, the VDD storage capacitor. This voltage is regulated to +5.5V. At this voltage, the internal oscillator is disabled. Simultaneous with the transfer of the voltage to C4, the positive side of capacitor C1 is switched to VCC and the negative side is connected to GND, allowing the charge pump cycle to begin again. The charge pump cycle will continue as long as the operational conditions for the internal oscillator are present. Since both V+ and V– are separately generated from VCC, in a no–load condition V+ and V– will be symmetrical. Older charge pump approaches that generate V– from V+ will show a decrease in the magnitude of V– compared to V+ due to the inherent inefficiencies in the design. The clock rate for the charge pump typically operates at 500kHz. The external capacitors can be as low as 0.1µF with a 16V breakdown voltage rating. SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 10 RECEIVER +2.7V 0V RS-232 INPUT VOLTAGES -2.7V VCC STATUS 0V S H U T D O W N tSTSL tSTSH tONLINE +5V DRIVER RS-232 OUTPUT VOLTAGES 0V -5V Figure 10. Auto-Online Timing Waveforms VCC = +5V +5V C1 + – C4 + – + C2 + – – VDD Storage Capacitor VSS Storage Capacitor –5V –5V C3 Figure 11. Charge Pump — Phase 1 VCC = +5V C4 + – + C1 + – C2 + – – VDD Storage Capacitor VSS Storage Capacitor –10V C3 Figure 12. Charge Pump — Phase 2 SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 11 [ T ] +6V a) C2+ 1 2 2 T 0V 0V b) C2T Ch1 2.00V Ch2 2.00V M 1.00µs Ch1 1.96V -6V Figure 13. Charge Pump Waveforms VCC = +5V +5V C1 + – C4 + – + C2 + – – VDD Storage Capacitor VSS Storage Capacitor –5V –5V C3 Figure 14. Charge Pump — Phase 3 VCC = +5V +10V C1 + – C4 + – + C2 + – – VDD Storage Capacitor VSS Storage Capacitor C3 Figure 15. Charge Pump — Phase 4 SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 12 TBD Figure 16. Driver Output Voltages vs. Load Current per Transmitter VCC C5 + 0.1µF 26 VCC 28 C1+ V+ C1 + 0.1µF 25 C11 + C2 0.1µF C2+ C2- 27 C3 SP3238E V- + 0.1µF 3 4 C4 16 R1OUT 21 R1OUT 5kΩ 20 R2OUT 5kΩ 18 R3OUT 5kΩ 24 T1IN 23 T2IN 22 T3IN 19 T4IN 17 T5IN VCC + R1IN R2IN R3IN 0.1µF 8 9 11 T1OUT T2OUT T3OUT T4OUT T5OUT 5 6 7 10 12 14 13 DB-9 Connector 6 7 8 9 1 2 3 4 5 SHUTDOWN ONLINE To µP Supervisor Circuit 15 STATUS GND 2 DB-9 Connector Pins: 1. Received Line Signal Detector 2. Received Data 3. Transmitted Data 4. Data Terminal Ready 5. Signal Ground (Common) 6. 7. 8. 9. DCE Ready Request to Send Clear to Send Ring Indicator Figure 17. Circuit for the connectivity of the SP3238E with a DB-9 connector SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 13 SHUTDOWN INPUT HIGH HIGH HIGH HIGH LOW LOW ONLINE INPUT HIGH LOW LOW - RS-232 SIGNAL AT RECEIVER INPUT YES NO NO (100µs) YES NO STATUS OUTPUT HIGH LOW LOW LOW HIGH LOW TXOUT Active Active Active High-Z High-Z High-Z RXOUT Active Active Active High-Z High-Z High-Z R1OUT Active Active Active Active Active Active TRANSCEIVER STATUS Normal Operation Normal Operation Normal Operation Shutdown (Auto-Online) Shutdown Shutdown Table 2. Auto-Online Logic Inactive Detection Block RXINACT RXIN RS-232 Receiver Block RXOUT Figure 18. Stage I of Auto-Online Circuitry Delay Stage Delay Stage Delay Stage STATUS R1INACT R2INACT R3INACT SHUTDOWN Figure 19. Stage II of Auto-Online Circuitry SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 14 Auto-Online Circuitry The SP3238E device has a patent pending Auto-Online circuitry on board that saves power in applications such as laptop computers, palmtop (PDA) computers, and other portable systems. The S P3238E d evice incorporates an Auto-Online c ircuit that automatically enables itself when the external transmitters are enabled and the cable is connected. Conversely, the Auto-Online circuit also disables most of the internal circuitry when the device is not being used and goes into a standby mode where the device typically draws 1µA. This function can also be externally controlled by the ONLINE pin. When this pin is tied to a logic LOW, the Auto-Online function is active. Once active, the device is enabled until there is no activity on the receiver inputs. The receiver input typically sees at least +3V, which are generated from the transmitters at the other end of the cable with a +5V minimum. When the external transmitters are disabled or the cable is disconnected, the receiver inputs will be pulled down by their internal 5kΩ resistors to ground. When this occurs over a period of time, the internal transmitters will be disabled and the device goes into a shutdown or standy mode. When ONLINE is HIGH, the Auto-Online mode is disabled. The Auto-Online circuit has two stages: 1) Inactive Detection 2) Accumulated Delay The first stage, shown in Figure 18, detects an inactive input. A logic HIGH is asserted on RXINACT if the cable is disconnected or the external transmitters are disabled. Otherwise, RXINACT will be at a logic LOW. This circuit is duplicated for each of the other receivers. The second stage of the Auto-Online circuitry, shown in Figure 19, processes all the receiver's RXINACT signals with an accumulated delay that disables the device to a 1µA supply current. The STATUS pin goes to a logic LOW when the cable is disconnected, the external transmitters are disabled, or the SHUTDOWN pin is invoked. The typical accumulated delay is around 20µs. When the drivers or internal charge pump are disabled, the supply current is reduced to 1µA. This can commonly occur in hand-held or portable applications where the RS-232 cable is disconnected or the RS-232 drivers of the connected peripheral are turned off. The Auto-Online mode can be disabled by the SHUTDOWN pin. If this pin is a logic LOW, the Auto-Online function will not operate regardless of the logic state of the ONLINE pin. Table 3 summarizes the logic of the Auto-Online operating modes. The truth table logic of the driver and receiver outputs can be found in Table 2. The STATUS pin outputs a logic LOW signal if the device is shutdown. This pin goes to a logic HIGH when the external transmitters are enabled and the cable is connected. When the SP3238E device is shut down, the charge pump is turned off. V+ charge pump output decays to VCC, the V- output decays to GND. The decay time will depend on the size of capacitors used for the charge pump. Once in shutdown, the time required to exit the shut down state and have valid V+ and V- levels is typically 200µs. For easy programming, the STATUS can be used to indicate DTR or a Ring Indicator signal. Tying ONLINE and SHUTDOWN together will bypass the Auto-Online circuitry so this connection acts like a shutdown input pin. SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 15 ESD TOLERANCE The SP3238E device incorporates ruggedized ESD cells on all driver output and receiver input pins. The ESD structure is improved over our previous family for more rugged applications and environments sensitive to electro-static discharges and associated transients. The improved ESD tolerance is at least +15kV without damage nor latch-up. There are different methods of ESD testing applied: a) MIL-STD-883, Method 3015.7 b) IEC1000-4-2 Air-Discharge c) IEC1000-4-2 Direct Contact normal usage. The transceiver IC receives most of the ESD current when the ESD source is applied to the connector pins. The test circuit for IEC1000-4-2 is shown on Figure 21. There are two methods within IEC1000-4-2, the Air Discharge method and the Contact Discharge method. With the Air Discharge Method, an ESD voltage is applied to the equipment under test (EUT) through air. This simulates an electrically charged person ready to connect a cable onto the rear of the system only to find an unpleasant zap just before the person touches the back panel. The high energy potential on the person discharges through an arcing path to the rear panel of the system before he or she even touches the system. This energy, whether discharged directly or through air, is predominantly a function of the discharge current rather than the discharge voltage. Variables with an air discharge such as approach speed of the object carrying the ESD potential to the system and humidity will tend to change the discharge current. For example, the rise time of the discharge current varies with the approach speed. The Contact Discharge Method applies the ESD current directly to the EUT. This method was devised to reduce the unpredictability of the ESD arc. The discharge current rise time is constant since the energy is directly transferred without the air-gap arc. In situations such as hand held systems, the ESD charge can be directly discharged to the equipment from a person already holding the equipment. The current is transferred on to the keypad or the serial port of the equipment directly and then travels through the PCB and finally to the IC. RS RS The Human Body Model has been the generally accepted ESD testing method for semiconductors. This method is also specified in MIL-STD-883, Method 3015.7 for ESD testing. The premise of this ESD test is to simulate the human body’s potential to store electro-static energy and discharge it to an integrated circuit. The simulation is performed by using a test model as shown in Figure 20. This method will test the IC’s capability to withstand an ESD transient during normal handling such as in manufacturing areas where the ICs tend to be handled frequently. The IEC-1000-4-2, formerly IEC801-2, is generally used for testing ESD on equipment and systems. For system manufacturers, they must guarantee a certain amount of ESD protection since the system itself is exposed to the outside environment and human presence. The premise with IEC1000-4-2 is that the system is required to withstand an amount of static electricity when ESD is applied to points and surfaces of the equipment that are accessible to personnel during RC RC SW1 SW1 DC Power Source SW2 SW2 CS S Device Under Test Figure 20. ESD Test Circuit for Human Body Model SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 16 Contact-Discharge Module RC RC SW1 SW1 DC Power Source RS RS RV SW2 SW2 CS S Device Under Test RS and RV add up to 330Ω for IEC1000-4-2. Figure 21. ESD Test Circuit for IEC1000-4-2 The circuit model in Figures 20 and 21 represent the typical ESD testing circuit used for all three methods. The CS is initially charged with the DC power supply when the first switch (SW1) is on. Now that the capacitor is charged, the second switch (SW2) is on while SW1 switches off. The voltage stored in the capacitor is then applied through RS, the current limiting resistor, onto the device under test (DUT). In ESD tests, the SW2 switch is pulsed so that the device under test receives a duration of voltage. For the Human Body Model, the current limiting resistor (RS) and the source capacitor (CS) are 1.5kΩ an 100pF, respectively. For IEC-1000-42, the current limiting resistor (RS) and the source capacitor (CS) are 330Ω an 150pF, respectively. The higher CS value and lower RS value in the IEC1000-4-2 model are more stringent than the Human Body Model. The larger storage capacitor injects a higher voltage to the test point when SW2 is switched on. The lower current limiting resistor increases the current charge onto the test point. DEVICE PIN TESTED Driver Outputs Receiver Inputs 30A 15A 0A t=0ns t¥ Figure 22. ESD Test Waveform for IEC1000-4-2 t=30ns HUMAN BODY MODEL ±15kV ±15kV i¥ Air Discharge ±15kV ±15kV IEC1000-4-2 Direct Contact ±8kV ±8kV Level 4 4 Table 3. Transceiver ESD Tolerance Levels SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 17 PACKAGE: PLASTIC SHRINK SMALL OUTLINE (SSOP) E H D A Ø e B A1 L DIMENSIONS (Inches) Minimum/Maximum (mm) A A1 B D E e H L Ø 28–PIN 0.068/0.078 (1.73/1.99) 0.002/0.008 (0.05/0.21) 0.010/0.015 (0.25/0.38) 0.397/0.407 (10.07/10.33) 0.205/0.212 (5.20/5.38) 0.0256 BSC (0.65 BSC) 0.301/0.311 (7.65/7.90) 0.022/0.037 (0.55/0.95) 0°/8° (0°/8°) SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 18 PACKAGE: PLASTIC THIN SMALL OUTLINE (TSSOP) E2 E D A Ø e B A1 L DIMENSIONS in inches (mm) Minimum/Maximum A A1 B D E e E2 L Ø 28–PIN 0.068/0.078 (1.73/1.99) 0.002/0.008 (0.05/0.21) 0.010/0.015 (0.25/0.38) 0.397/0.407 (10.07/10.33) 0.205/0.212 (5.20/5.38) 0.0256 BSC (0.65 BSC) 0.301/0.311 (7.65/7.90) 0.022/0.037 (0.55/0.95) 0°/8° (0°/8°) SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers © Copyright 1999 Sipex Corporation 19 ORDERING INFORMATION ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Model SP3238ECA SP3238ECY SP3238EEA SP3238EEY Temperature Range 0°C to +70°C 0°C to +70°C ○ Package Types 28-pin SSOP 28-pin TSSOP 28-pin SSOP 28-pin TSSOP ○ ○ ○ Please consult the factory for pricing and availability on a Tape-On-Reel option. Corporation SIGNAL PROCESSING EXCELLENCE Sipex Corporation Headquarters and Sales Office 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: sales@sipex.com Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 European Sales Offices: GERMANY: Sipex GmbH Gautinger Strasse 10 82319 Starnberg TEL: 49.81.51.89810 FAX: 49.81.51.29598 e-mail: sipex-starnberg@t-online.de Far East: JAPAN: Nippon Sipex Corporation Yahagi No. 2 Building 3-5-3 Uchikanda, Chiyoda-ku Tokyo 101 TEL: 81.3.3256.0577 FAX: 81.3.3256.0621 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. SP3238EDS/04 SP3238E +3.0V to +5.5V RS-232 Transceivers 20 ○ -40°C to +85°C -40°C to +85°C ○ ○ © Copyright 1999 Sipex Corporation