® SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver FEATURES ■ Meets true EIA/TIA-232-F Standards from a +3.0V to +5.5V power supply ■ Interoperable with EIA/TIA-232 and adheres to EIA/TIA-562 down to a +2.7V power source ■ AUTO ON-LINE® circuitry automatically wakes up from a 1µA shutdown ■ Minimum 250Kbps data rate under load ■ Regulated Charge Pump Yields Stable RS-232 Outputs Regardless of VCC Variations ■ Enhanced ESD Specifications for all TTL and RS-232 I/O lines: +15KV Human Body Model +15KV IEC1000-4-2 Air Discharge +8KV IEC1000-4-2 Contact Discharge 28 C1+ C2+ 1 GND 2 27 V+ C2- 3 26 VCC 25 C1- V- 4 T1OUT 5 T2OUT 6 T3OUT 7 SP3238EE 24 T1IN 23 T2IN 22 T3IN R1IN 8 21 R1OUT R2IN 9 20 T4OUT 10 R2OUT 19 T4IN R3IN 11 18 T5OUT 12 17 T5IN ONLINE 13 16 R1OUT SHUTDOWN 14 R3OUT 15 STATUS Now Available in Lead Free Packaging DESCRIPTION The SP3238EE device is an RS-232 transceiver solution intended for portable or hand-held applications such as notebook and palmtop computers. The SP3238EE 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 SP3238EE 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 SP3238EE includes one complementary receiver that remains alert to monitor an external device's Ring Indicate signal while the device is shutdown. The AUTO ON-LINE® 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. Applicable U.S. Patents - 5,306,954; and other patents pending. Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 1 © Copyright 2005 Sipex Corporation ABSOLUTE MAXIMUM RATINGS Power Dissipation per package 28-pin SSOP (derate 11.2mW/oC above +70oC).................900mW 28-pin TSSOP (derate 13.2mW/oC above +70oC)...............1100mW 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, .....................................-0.3V to +6.0V RxIN...................................................................+25V Output Voltages TxOUT.............................................................+13.2V RxOUT, STATUS.......................-0.3V to (VCC + 0.3V) Short-Circuit Duration TxOUT.....................................................Continuous Storage Temperature......................-65°C to +150°C Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V. ELECTRICAL CHARACTERISTICS VCC = +3.0 to +5.5, C1 -C4 = 0.1µF (tested at 3.3V + 5%), C1-C4 = 0.22µF (tested at 3.3V + 10%), C1 = 0.047µF, and C2-C4 = 0.33µF (tested at 5.0V + 10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER MIN. TYP. MAX. UNITS CONDITIONS Supply Current, AUTO ON-LINE® 1.0 10 µA All RxIN open, ONLINE = GND, SHUTDOWN = VCC, all TxIN=GND or VCC Supply Current, Shutdown 1.0 10 µA SHUTDOWN=GND, all TxIN=GND or VCC Supply Current, AUTO ON-LINE® Disabled 0.3 1.0 DC CHARACTERISTICS mA ONLINE = SHUTDOWN = VCC, no load, all TxIN=GND or VCC LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshold LOW HIGH 0.8 V VCC = +3.3V or +5.0V, TxIN ONLINE, SHUTDOWN 2.4 Input Leakage Current +0.01 +1.0 µA TxIN, ONLINE, SHUTDOWN TA = 25° C Output Leakage Current +0.05 +10 µA Receivers Disabled 0.4 V IOUT = 1.6mA V IOUT = -1.0mA Output Voltage LOW Output Voltage HIGH Date: 02/24/05 VCC - 0.6 VCC - 0.1 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 2 © Copyright 2005 Sipex Corporation ELE CTRICAL CHARACTERISTICS VCC = +3.0 to +5.5, C1 -C4 = 0.1µF (tested at 3.3V + 5%), C1-C4 = 0.22µF (tested at 3.3V + 10%), C1 = 0.047µF, and C2-C4 = 0.33µF (tested at 5.0V + 10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER MIN. TYP. Output Voltage Swing ±5.0 ±5.4 Output Resistance 300 MAX. UNITS CONDITIONS DRIVER OUTPUTS Output Short-Circuit Current ±3 5 V All driver outputs loaded with 3KΩ to GND Ω VCC = V+ = V- = 0V, VOUT = ±2V ±60 mA 25 V VOUT = GND RECEIVER INPUTS Input Voltage Range -25 Input Threshold LOW 0.6 1.2 V VCC = 3.3V Input Threshold LOW 0.8 1.5 V VCC = 5.0V Input Threshold HIGH 1.5 2.4 V VCC = 3.3V Input Threshold HIGH 1.8 2.4 V VCC = 5.0V Input Hysteresis 0.5 Input Resistance 3 V 5 7 kΩ AUTO ON-LINE® CIRCUITRY CHARACTERISTICS (ONLINE = GND, SHUTDOWN = VCC) STATUS Output Voltage LOW STATUS Output Voltage HIGH 0.4 VCC - 0.6 V IOUT = 1.6mA V IOUT = -1.0mA Receiver Threshold to Drivers Enabled (tONLINE) 200 µS Figure 10 Receiver Positive or Negative Threshold to STATUS HIGH (tSTSH) 0.5 µS Figure 10 Receiver Positive or Negative Threshold to STATUS LOW (tSTSL) 20 µS Figure 10 Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 3 © Copyright 2005 Sipex Corporation ELE CTRICAL CHARACTERISTICS VCC = +3.0 to +5.5, C1 -C4 = 0.1µF (tested at 3.3V + 5%), C1-C4 = 0.22µF (tested at 3.3V + 10%), C1 = 0.047µF, and C2-C4 = 0.33µF (tested at 5.0V + 10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER MIN. TYP. MAX. UNITS CONDITIONS TIMING CHARACTERISTICS Maximum Data Rate 250 RL = 3kΩ, CL = 1000pF, one driver switching kbps Receiver Propagation Delay t PHL t PLH 0.15 0.15 µS Receiver input to receiver output, CL = 150pF Receiver Output Enable Time 200 ns Normal operation Receiver Output Disable Time 200 ns Normal operation Driver Skew 100 ns I tPLH - tPHL I,TA = 25OC Receiver Skew 50 ns I tPLH - tPHL I Transition-Region Slew Rate 30 VCC = 3.3V, RL = 3kΩ, TAMB = 25OC, measurements taken from -3.0V to +3.0V or +3.0V to -3.0V V/µs TYPICAL PERFOMANCE CHARACTERISTICS Unless otherwise noted, the following perfomance characteristics apply for VCC = +3.3V, 250kbps data rate, all drivers loaded with 3kΩ, 0.1µF charge pump capacitors, and TAMB = +25°C. SLEW RATE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT vs. LOAD CAPACITANCE 6 25 4 20 2 15 0 -2 0 1000 2000 3000 4000 5000 VOH VOL POS. SR NEG SR 10 5 -4 0 0 -6 1000 2000 3000 4000 5000 pF pF SUPPLY CURRENT vs LOAD CAPACITANCE 60 50 40 250Kbps 120Kbps 20Kbps 30 20 10 0 0 1000 2000 3000 4000 5000 pF Figure 3. Supply Current VS. Load Capacitance when Transmitting Data Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 4 © Copyright 2005 Sipex Corporation PIN DESCRIPTION NAME PIN NO. FUNCTION C2+ Positive terminal of the symmetrical charge-pump capacitor C2. 1 GND Ground. 2 C2- Negative terminal of the symmetrical charge-pump capacitor C2. 3 V- Regulated -5.5V output generated by the charge pump. 4 T1OUT RS-232 driver output. 5 T2OUT RS-232 driver output. 6 T3OUT RS-232 driver output. 7 R1IN RS-232 receiver input. 8 R2IN RS-232 receiver input. 9 T4OUT RS-232 driver output. 10 R3IN RS-232 receiver input. 11 T5OUT RS-232 driver output. 12 Apply logic HIGH to override AUTO ON-LINE® circuitry keeping drivers active (SHUTDOWN must also be logic HIGH, refer to Table 2). 13 Apply logic LOW to shut down drivers and charge pump. This overrides all AUTO ON-LINE® circuitry and ONLINE (refer to Table 2). 14 TTL/CMOS Output indicating if a RS-232 signal is present on any receiver input. 15 Non-inverting receiver-1 output, active in shutdown. 16 TTL/CMOS driver input. 17 TTL/CMOS receiver output. 18 TTL/CMOS driver input. 19 R2OUT TTL/CMOS receiver output. 20 R1OUT TTL/CMOS receiver output. 21 T3IN TTL/CMOS driver input. 22 T2IN TTL/CMOS driver input. 23 T1IN TTL/CMOS driver input. 24 C1- Negative terminal of the symmetrical charge-pump capacitor C1. 25 VCC +3.0V to +5.5V supply voltage. 26 V+ Regulated +5.5V output generated by the charge pump. 27 C1+ Positive terminal of the symmetrical charge-pump capacitor C1 28 ONLINE SHUTDOWN STATUS R1OUT T5IN R3OUT T4IN Table 1. Device Pin Description Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 5 © Copyright 2005 Sipex Corporation PIINOUT 28 C1+ C2+ 1 GND 2 27 V+ C2- 3 26 VCC 25 C1- V- 4 T1OUT 5 T2OUT 6 SP3238EE 24 T1IN 23 T2IN 22 T3IN T3OUT 7 R1IN 8 21 R1OUT R2IN 9 20 T4OUT 10 R2OUT 19 T4IN R3IN 11 18 T5OUT 12 17 T5IN ONLINE 13 16 R1OUT R3OUT 15 STATUS SHUTDOWN 14 Figure 4. SP3238E Pinout Configuration Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 6 © Copyright 2005 Sipex Corporation VCC C5 C1 + + 26 VCC 0.1µF 28 C1+ 0.1µF C2 0.1µF TTL/CMOS INPUTS 27 C3 25 C11 C2+ + V+ SP3238EE V- + 0.1µF 4 C4 3 C224 T1IN T1OUT 5 23 T2IN T2OUT 6 22 T3IN T3OUT 7 19 T4IN T4OUT 10 17 T5IN T5OUT 12 + 0.1µF RS-232 OUTPUTS 16 R1OUT 21 R1OUT R1IN 8 R2IN 9 R3IN 11 5kΩ TTL/CMOS OUTPUTS 20 R2OUT 5kΩ 18 R3OUT VCC 5kΩ 14 13 To µP Supervisor Circuit RS-232 INPUTS SHUTDOWN ONLINE 15 STATUS GND 2 Figure 5. SP3238E Typical Operating Circuit Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 7 © Copyright 2005 Sipex Corporation DESCRIPTION The SP3238EE 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 guarantee a data rate of 250kbps fully loaded. The SP3238EE device is an ideal choice for power sensitive designs. The SP3238EE device features AUTO ON-LINE® 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. The SP3238EE is a 5-driver/3-receiver device, ideal for portable or hand-held applications. The SP3238EE 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. THEORY OF OPERATION The SP3238EE device is made up of four basic circuit blocks: 1. Drivers, 2. Receivers, 3. the Sipex proprietary charge pump, and 4. AUTO ON-LINE® 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. VCC C5 C1 + + 28 C1+ 0.1µF + 0.1µF RxD UART or Serial µC V+ 27 C3 25 C11 C2+ C2 26 VCC 0.1µF SP3238EE + 0.1µF V- 4 C4 3 C224 T1IN T1OUT 5 T2OUT 6 CTS 23 T2IN DSR 22 T3IN T3OUT 7 DCD 19 T4IN T4OUT 10 RI 17 T5IN T5OUT 12 + 0.1µF RS-232 OUTPUTS The drivers can guarantee a data rate of 250kbps fully loaded with 3kΩ in parallel with 1000pF, ensuring compatibility with PC-to-PC communication software. All unused driver inputs must be connected to VCC or GND. 16 R1OUT TxD 21 R1OUT RTS 20 R2OUT DTR 18 R3OUT R1IN 8 5kΩ R2IN 9 5kΩ VCC RS-232 INPUTS R3IN 11 5kΩ 14 13 15 SHUTDOWN ONLINE STATUS 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. GND 2 RESET µP Supervisor IC VIN Figure 6. Interface Circuitry Controlled by Microprocessor Supervisory Circuit Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 8 © Copyright 2005 Sipex Corporation 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 five drivers active at 120kbps with typical RS-232 loads in parallel with 1000pF capacitors. Figure 6 shows the test results where one driver was active at 250kbps and all five drivers loaded with an RS232 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. VCC C5 C1 + + 0.1µF VCC C1+ V+ 0.1µF + C3 0.1µF C1C2+ C2 + SP3238EE VC4 0.1µF + C2TxOUT TxIN LOGIC INPUTS RxOUT LOGIC OUTPUTS 0.1µF RxIN 1000pF 5kΩ VCC ONLINE Receivers SHUTDOWN The receivers convert ±5.0V EIA/TIA-232 levels to TTL or CMOS logic output levels. GND Receivers are not active when in shutdown. If there is no activity present at the receivers for a period longer than 100µs during AUTO ONLINE® mode 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. Figure 7. Loopback Test Circuit for RS-232 Driver Data Transmission Rates Indicator (RI) from a peripheral to be monitored without forward biasing the TTL/CMOS inputs of the other devices connected to the receiver outputs. 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 The SP3238EE 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 Figure 8. Loopback Test Circuit Result at 120kbps (All Drivers Fully Loaded) Date: 02/24/05 Figure 9. Loopback Test Circuit result at 250kbps (All Drivers Fully Loaded) SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 9 © Copyright 2005 Sipex Corporation 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. Phase 3 (Figure 14) — 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. 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. Phase 4 (Figure 15) — 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. 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 (Figure 13). A description of each phase follows. 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. Phase 1 (Figure 11) — 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 (Figure 12) — 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. Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 10 © Copyright 2005 Sipex Corporation S H U T RECEIVER +2.7V 0V RS-232 INPUT VOLTAGES -2.7V D O W N VCC STATUS 0V tSTSL tSTSH tONLINE +5V DRIVER RS-232 OUTPUT VOLTAGES 0V -5V Figure 10. AUTO ON-LINE® Timing Waveforms VCC = +5V +5V C1 + – C2 –5V C4 + – – + VDD Storage Capacitor + – –5V VSS Storage Capacitor C3 Figure 11. Charge Pump — Phase 1 VCC = +5V C4 C1 + – C2 + – – + + – –10V VDD Storage Capacitor VSS Storage Capacitor C3 Figure 12. Charge Pump — Phase 2 Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 11 © Copyright 2005 Sipex Corporation [ T ] +6V a) C2+ T 1 2 0V 2 0V b) C2T Ch1 2.00V Ch2 2.00V M 1.00µs Ch1 1.96V -6V Figure 13. Charge Pump Waveforms VCC = +5V +5V C4 + C1 + C2 – –5V – + – + – VDD Storage Capacitor VSS Storage Capacitor C3 –5V Figure 14. Charge Pump — Phase 3 VCC = +5V +10V C4 + C1 + – C2 – + – – + VDD Storage Capacitor VSS Storage Capacitor C3 Figure 15. Charge Pump — Phase 4 Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 12 © Copyright 2005 Sipex Corporation VCC C5 + 26 VCC 0.1µF 28 C1 + C1+ 0.1µF 25 C11 C2 + C2+ V+ SP3238EE C3 0.1µF 3 27 V- C2- + 0.1µF 4 C4 16 R1OUT 0.1µF + R1IN 8 R2IN 9 R3IN 11 24 T1IN T1OUT 5 23 T2IN T2OUT 6 22 T3IN T3OUT 7 19 T4IN T4OUT 10 17 T5IN T5OUT 12 21 R1OUT 5kΩ 20 R2OUT 5kΩ 18 R3OUT 5kΩ VCC 14 13 To µP Supervisor Circuit DB-9 Connector SHUTDOWN ONLINE 15 STATUS 6 7 8 9 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. 1 2 3 4 5 DCE Ready Request to Send Clear to Send Ring Indicator Figure 16. Circuit for the connectivity of the SP3238E with a DB-9 connector Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 13 © Copyright 2005 Sipex Corporation SHUTDOWN INPUT ONLINE INPUT RS-232 SIGNAL AT RECEIVER INPUT STATUS OUTPUT TXOUT RXOUT R1OUT TRANSCEIVER STATUS HIGH - YES HIGH Active Active Active Normal Operation HIGH HIGH NO LOW Active Active Active Normal Operation HIGH LOW NO (>100µs) LOW High-Z Active Active Shutdown (AUTO ON-LINE® ) LOW - YES HIGH High-Z High-Z Active Shutdown LOW - NO LOW High-Z High-Z Active Shutdown ® Table 2. AUTO ON-LINE Logic Inactive Detection Block RS-232 Receiver Block RXIN RXINACT RXOUT Figure 17. Stage I of AUTO ON-LINE® Circuitry Delay Stage Delay Stage Delay Stage STATUS R1INACT R2INACT R3INACT Figure 18. Stage II of AUTO ON-LINE® Circuitry Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 14 © Copyright 2005 Sipex Corporation AUTO ON-LINE® Circuitry 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 SP3238EE device has a patent pending AUTO ON-LINE® circuitry on board that saves power in applications such as laptop computers, palmtop (PDA) computers, and other portable systems. The SP3238EE device incorporates an AUTO ON-LINE® circuit that automatically enables itself when the external transmitters are enabled and the cable is connected. Conversely, the AUTO ON-LINE® 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 is externally controlled by the ONLINE pin. When this pin is tied to a logic LOW, the AUTO ON-LINE® 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 standby mode. When ONLINE is HIGH, the AUTO ONLINE® mode is disabled. The AUTO ON-LINE® mode can be disabled by the SHUTDOWN pin. If this pin is a logic LOW, the AUTO ON-LINE® function will not operate regardless of the logic state of the ONLINE pin. Table 2 summarizes the logic of the AUTO ON-LINE® operating modes and the truth table logic of the driver and receiver outputs. The STATUS pin outputs a logic LOW signal when there is no valid RS-232 signal present on any receiver input. 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 200ms. For easy programming, the STATUS pin can be used to indicate DTR or a Ring Indicator signal. Tying ONLINE and SHUTDOWN together will bypass the AUTO ON-LINE® circuitry so this connection acts like a shutdown input pin. The AUTO ON-LINE® circuit has two stages: 1) Inactive Detection 2) Accumulated Delay The first stage, shown in Figure 17, 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 ON-LINE® circuitry, shown in Figure 18, 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 or when the external transmitters are disabled. Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 15 © Copyright 2005 Sipex Corporation ESD TOLERANCE The SP3238EE device incorporates ruggedized ESD cells on all driver and receiver input and output pins. The ESD structure is improved over our previous family for more rugged applications and environments sensitive to electrostatic discharges and associated transients. The improved ESD tolerance is at least +15kV without damage nor latch-up. 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 20. 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. 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 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 19. 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 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. 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 RSS RC C SW2 SW2 SW1 SW1 CSS DC Power Source Device Under Test Figure 19. ESD Test Circuit for Human Body Model Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 16 © Copyright 2005 Sipex Corporation Contact-Discharge Module RSS RC C RV SW2 SW1 Device Under Test CSS DC Power Source RS and RV add up to 330Ω for IEC1000-4-2. Figure 20. ESD Test Circuit for IEC1000-4-2 i➙ The circuit model in Figures 19 and 20 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. 30A 15A 0A 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. t=0ns t➙ t=30ns Figure 21. ESD Test Waveform for IEC1000-4-2 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 HUMAN BODY MODEL Air Discharge Driver Outputs Receiver Inputs Logic Inputs Logic Outputs ±15kV ±15kV ±15kV ±15kV ±15kV ±15kV ±15kV ±15kV IEC1000-4-2 Direct Contact ±8kV ±8kV ±8kV ±8kV Level 4 4 Table 3. Transceiver ESD Tolerance Levels Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 17 © Copyright 2005 Sipex Corporation PACKAGE: 28 Pin SSOP D N SEE DETAIL “A” E1 1 E 2 INDEX AREA D x E1 2 2 2 NX R R1 A Gauge Plane Seaing Plane A L Ø L1 DETAIL A 28 Pin SSOP JEDEC MO-150 (AH) Variation MIN NOM MAX SYMBOL A 2 A1 0.05 A2 1.65 1.75 1.85 b 0.22 0.38 c 0.09 0.25 D 9.9 10.2 10.5 E 7.4 7.8 8.2 E1 5 5.3 5.6 L 0.55 0.75 0.95 L1 1.25 REF ø 0º 4º 8º A2 A Seating Plane A1 b WITH LEAD FINISH Note: Dimensions in (mm) c BASE METAL b Section A-A Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 18 © Copyright 2005 Sipex Corporation PACKAGE: 28 Pin TSSOP D e Ø2 E1 E Seaing Plane L Ø3 L1 1 Ø1 DETAIL A 2 INDEX AREA D x E1 2 2 SEE DETAIL “A” A2 A Seating Plane b A1 B B 28 Pin TSSOP JEDEC MO-153 (AE) Variation MIN NOM MAX SYMBOL A 1.2 A1 0.05 0.15 A2 0.8 1 1.05 b 0.19 0.3 c 0.09 0.2 D 9.6 9.7 9.8 0.65 BSC e 6.40 BSC E E1 4.3 4.4 4.5 L 0.45 0.6 0.75 1.00 REF L1 Ø1 0º 8º Ø2 12º REF Ø3 12º REF Note: Dimensions in (mm) Date: 02/24/05 b C Section B-B SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 19 © Copyright 2005 Sipex Corporation ORDERING INFORMATION Model Temperature Range Package Types SP3238EECA.................................................0°C to +70°C.....................................................28-pin SSOP SP3238EECA/TR...........................................0°C to +70°C.....................................................28-pin SSOP SP3238EECY.................................................0°C to +70°C.....................................................28-pin TSSOP SP3238EECY/TR...........................................0°C to +70°C.....................................................28-pin TSSOP SP3238EEEA.................................................-40°C to +85°C..................................................28-pin SSOP SP3238EEEA/TR...........................................-40°C to +85°C..................................................28-pin SSOP SP3238EEEY.................................................-40°C to +85°C..................................................28-pin TSSOP SP3238EEEY/TR...........................................-40°C to +85°C..................................................28-pin TSSOP Available in lead free packaging. To order add “-L” suffix to part number. Example: SP3238EEEY/TR = standard; SP3238EEEY-L/TR = lead free /TR = Tape and Reel Pack quantity is 1,500 for SSOP and TSSOP. CLICK HERE TO ORDER SAMPLES Corporation ANALOG EXCELLENCE Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sales Office 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: [email protected] 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. Date: 02/24/05 SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver 20 © Copyright 2005 Sipex Corporation