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SP3238E
Intelligent +3.0V to +5.5V RS-232 Transceiver
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(R) circuitry automatically wakes up from a 1A shutdown Minimum 250Kbps data rate under load Regulated Charge Pump Yields Stable RS-232 Outputs Regardless of VCC Variations 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 0.1F 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 ON-LINE(R) 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 1A. SELECTION TABLE
Device Power Supplies 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 ON-LINE(R)
TTL 3-State
Circuitry NO YES YES YES YES YES YES YES
No. of Pins 16 20 28 28
SP3220E SP3223E SP3243E SP3238E
+3.0V to +5.5V +3.0V to +5.5V +3.0V to +5.5V +3.0V to +5.5V
Applicable U.S. Patents - 5,306,954; and other patents pending.
Rev. 3/20/03 SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver (c) Copyright 2003 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, .....................................-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......................-65C to +150C
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 13V.
SPECIFICATIONS
VCC = +3.0 to +5.5, C1 -C4 = 0.1F (tested at 3.3V + 5%), C1-C4 = 0.22F (tested at 3.3V + 10%), C1 = 0.047F, and C2-C4 = 0.33F (tested at 5.0V + 10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER DC CHARACTERISTICS Supply Current, AUTO ON-LINE(R)
MIN.
TYP.
MAX.
UNITS
CONDITIONS
1.0
10
A
All RxIN open, ONLINE = GND, SHUTDOWN = VCC, all TxIN=GND or VCC SHUTDOWN=GND, all TxIN=GND or VCC ONLINE = SHUTDOWN = VCC, no load, all TxIN=GND or VCC
Supply Current, Shutdown Supply Current, AUTO ON-LINE(R) Disabled 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
1.0 0.3
10 1. 0
A
mA
0.8 2.4 +0.01 +0.05 +1.0 +10 0.4 VCC - 0.1
V A A V V
VCC = +3.3V or +5.0V, TxIN ONLINE, SHUTDOWN TxIN, ONLINE, SHUTDOWN TA = 25 C Receivers Disabled IOUT = 1.6mA IOUT = -1.0mA
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
2
SPECIFICATIONS
VCC = +3.0 to +5.5, C1 -C4 = 0.1F (tested at 3.3V + 5%), C1-C4 = 0.22F (tested at 3.3V + 10%), C1 = 0.047F, and C2-C4 = 0.33F (tested at 5.0V + 10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER DRIVER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit 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
All driver outputs loaded with 3K to GND VCC = V+ = V- = 0V, VOUT = 2V VOUT = GND
35
60
mA
-25 0.6 0.8 1.2 1.5 1.5 1.8 0.5 3 5
25
V V V VCC = 3.3V VCC = 5.0V VCC = 3.3V VCC = 5.0V
2.4 2.4
V V V
7
k
AUTO ON-LINE(R) CIRCUITRY CHARACTERISTICS (ONLINE = GND, SHUTDOWN = VCC)
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) VCC - 0.6 200 0.5 0.4 V V S S IOUT = 1.6mA IOUT = -1.0mA Figure 10 Figure 10
20
S
Figure 10
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
3
SPECIFICATIONS
VCC = +3.0 to +5.5, C1 -C4 = 0.1F (tested at 3.3V + 5%), C1-C4 = 0.22F (tested at 3.3V + 10%), C1 = 0.047F, and C2-C4 = 0.33F (tested at 5.0V + 10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER TIMING CHARACTERISTICS Maximum Data Rate Receiver Propagation Delay t PHL t PLH Receiver Output Enable Time Receiver Output Disable Time Driver Skew Receiver Skew Transition-Region Slew Rate
MIN.
TYP.
MAX.
UNITS
CONDITIONS
250
kbps
RL = 3k, CL = 1000pF, one driver switching Receiver input to receiver output, CL = 150pF Normal operation Normal operation I tPLH - tPHL I,TA = 25OC I tPLH - tPHL I VCC = 3.3V, RL = 3k, TAMB = 25OC, measurements taken from -3.0V to +3.0V or +3.0V to -3.0V
0.15 0.15
S
200 200 100 50 30
ns ns ns ns V/s
TYPICAL PERFOMANCE CHARACTERISTICS
Unless otherwise noted, the following perfomance characteristics apply for VCC = +3.3V, 250kbps data rate, all drivers loaded with 3k, 0.1F charge pump capacitors, and TAMB = +25C.
TRANSMITTER OUTPUT vs. LOAD CAPACITANCE
6 4 2 0 -2 0 -4 -6 pF 1000 2000 3000 4000 5000 VOH VOL
25 20 15 10 5 0 0 1000 2000 pF 3000 4000 5000 POS. SR NEG SR
SLEW RATE vs. LOAD CAPACITANCE
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
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PIN DESCRIPTION
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 symmetrical charge-pump capacitor C2. Ground. Negative terminal of the symmetrical charge-pump capacitor C2. 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 ON-LINE 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 AUTO ON-LINE(R) circuitry and ONLINE (refer to Table 2). TTL/CMOS Output indicating if a RS-232 signal is present on any receiver input. 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 symmetrical charge-pump capacitor C1. +3.0V to +5.5V supply voltage. Regulated +5.5V output generated by the charge pump. Positive terminal of the symmetrical charge-pump capacitor C1
(R)
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
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
5
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Unless otherwise noted, the following performance characteristics apply for VCC = +3.3V, 250kbps data rate, all drivers loaded with 3k, 0.1F charge pump capacitors, and TAMB = +25C.
SUPPLY CURRENT vs LOAD CAPACITANCE
60 50 40 30 20 10 0 0 1000 2000 pF 3000 4000 5000 250Kbps 120Kbps 20Kbps
Figure 3. Supply Current VS. Load Capacitance when Transmitting Data
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
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
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VCC + 26 VCC 28 C1+ 0.1F 25 C11 C2+ C2 + 0.1F 3 C224 T1IN 23 T2IN TTL/CMOS INPUTS 22 T3IN 19 T4IN 17 T5IN 16 R1OUT 21 R1OUT TTL/CMOS OUTPUTS 5k 20 R2OUT 5k 18 R3OUT
VCC
C5
0.1F
C1
+
V+
27 C3 + 0.1F
SP3238E
V-
4 C4 + 0.1F
T1OUT 5 T2OUT 6 T3OUT 7 T4OUT 10 T5OUT 12
RS-232 OUTPUTS
R1IN R2IN R3IN
8 9 11 RS-232 INPUTS
5k 14 13
SHUTDOWN ONLINE
To P Supervisor Circuit
15 STATUS
GND 2
Figure 5. SP3238E Typical Operating Circuit
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 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 guarantee a 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 ON-LINE(R) circuitry which reduces the power supply drain to a 1A 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 ON-LINE(R) 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 can guarantee a data rate of 250kbps fully loaded with 3k in parallel with 1000pF, ensuring compatibility with PC-to-PC communication software. All unused driver inputs must be connected to VCC or GND. The slew rate of the driver output is internally limited to a maximum of 30V/s 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 + 0.1F 28 C1+ 0.1F 25 C11 C2+ C2 + 0.1F 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 + 0.1F
C1
+
SP3238E
V- 4 C4 + 0.1F
RxD CTS DSR DCD RI
RS-232 OUTPUTS
UART or Serial C
TxD RTS DTR
VCC
21 R1OUT 5k 20 R2OUT 5k 18 R3OUT 5k 14 13 15
SHUTDOWN ONLINE STATUS
R1IN 8 R2IN
9
RS-232 INPUTS
R3IN 11
GND 2
RESET
P Supervisor IC
VIN
Figure 6. Interface Circuitry Controlled by Microprocessor Supervisory Circuit
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
8
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. Receivers The receivers convert 5.0V EIA/TIA-232 levels to TTL or CMOS logic output levels. Receivers are not active when in shutdown. If there is no activity present at the receivers for a period longer than 100s during AUTO ONLINE(R) mode or when SHUTDOWN is enabled, the device goes into a standby mode where the circuit draws 1A. The truth table logic of the driver and receiver outputs can be found in Table 2. 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
VCC +
C5
0.1F C1+ 0.1F C1C2+
VCC V+ C3 + 0.1F
C1
+
SP3238E
C2
+
VC4 + 0.1F
0.1F C2-
LOGIC INPUTS LOGIC OUTPUTS VCC
TxIN
TxOUT 1000pF
RxOUT 5k
RxIN
ONLINE SHUTDOWN GND
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
Figure 8. Loopback Test Circuit Result at 120kbps (All Drivers Fully Loaded)
Figure 9. Loopback Test Circuit result at 250kbps (All Drivers Fully Loaded)
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
9
noisy transmission lines. Should an input be left unconnected, an internal 5k 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 (Figure 13). A description of each phase follows. 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.
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. 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. 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 0.1F with a 16V breakdown voltage rating.
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 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 ON-LINE(R) 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
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
11
[
T
] +6V
a) C2+
1 2 2
T
0V 0V
b) C2T -6V Ch1 2.00V Ch2 2.00V M 1.00s Ch1 1.96V
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
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
12
VCC
C5
+
0.1F
26 VCC 28
C1+
V+
C1
+
0.1F
25 C11
+ C2 0.1F C2+
C2-
27
C3
SP3238E
V-
+
0.1F
3
4
C4 0.1F
16 R1OUT 21 R1OUT 5k 20 R2OUT 5k 18 R3OUT 5k 24 T1IN 23 T2IN 22 T3IN 19 T4IN 17 T5IN
VCC
+
R1IN R2IN R3IN
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 P 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 16. Circuit for the connectivity of the SP3238E with a DB-9 connector
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
13
SHUTDOWN INPUT HIGH HIGH HIGH LOW LOW
ONLINE INPUT HIGH LOW (R)
RS-232 SIGNAL AT RECEIVER INPUT YES NO NO (>100s) YES NO
STATUS OUTPUT HIGH LOW LOW HIGH LOW
TXOUT Active Active High-Z High-Z High-Z
RXOUT Active Active Active High-Z High-Z
R1OUT Active Active Active Active Active
TRANSCEIVER STATUS Normal Operation Normal Operation Shutdown (AUTO ON-LINE(R) ) Shutdown Shutdown
Table 2. AUTO ON-LINE Logic
Inactive Detection Block
RXINACT
RXIN
RS-232 Receiver Block
RXOUT
Figure 17. Stage I of AUTO ON-LINE(R) Circuitry
Delay Stage
Delay Stage
Delay Stage
STATUS
R1INACT R2INACT R3INACT
Figure 18. Stage II of AUTO ON-LINE(R) Circuitry
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
14
AUTO ON-LINE(R) Circuitry The SP3238E device has a patent pending AUTO ON-LINE(R) circuitry on board that saves power in applications such as laptop computers, palmtop (PDA) computers, and other portable systems. The SP3238E device incorporates an AUTO ON-LINE(R) circuit that automatically enables itself when the external transmitters are enabled and the cable is connected. Conversely, the AUTO ON-LINE(R) 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 1A. This function is externally controlled by the ONLINE pin. When this pin is tied to a logic LOW, the AUTO ON-LINE(R) 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 5k 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(R) mode is disabled. The AUTO ON-LINE(R) 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(R) circuitry, shown in Figure 18, processes all the receiver's RXINACT signals with an accumulated delay that disables the device to a 1A supply current. The STATUS pin goes to a logic LOW when the cable is disconnected or when the external transmitters are disabled. When the drivers or internal charge pump are disabled, the supply current is reduced to 1A. 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 ON-LINE(R) mode can be disabled by the SHUTDOWN pin. If this pin is a logic LOW, the AUTO ON-LINE(R) function will not operate regardless of the logic state of the ONLINE pin. Table 2 summarizes the logic of the AUTO ON-LINE(R) 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(R) circuitry so this connection acts like a shutdown input pin.
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 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 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. 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 S
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 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 C SW1 SW1
DC Power Source
SW2 SW2 CS S
Device Under Test
Figure 19. ESD Test Circuit for Human Body Model
Rev. 3/20/03 SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver (c) Copyright 2003 Sipex Corporation
16
Contact-Discharge Module
RC C SW1
DC Power Source
RS S
RV SW2
CS S
Device Under Test
RS and RV add up to 330 for IEC1000-4-2.
Figure 20. ESD Test Circuit for IEC1000-4-2
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. For the Human Body Model, the current limiting resistor (RS) and the source capacitor (CS) are 1.5k an 100pF, respectively. For IEC-1000-42, the current limiting resistor (RS) and the source capacitor (CS) are 330 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 21. 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
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
17
PACKAGE: PLASTIC SHRINK SMALL OUTLINE (SSOP)
E H
D A O e B A1 L
DIMENSIONS (Inches) Minimum/Maximum (mm) A A1 B D E e H L O
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)
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
18
PACKAGE: PLASTIC THIN SMALL OUTLINE (TSSOP)
e
0.126 BSC (3.2 BSC) 0.252 BSC (6.4 BSC) 1.0 OIA 0.169 (4.30) 0.177 (4.50)
DIMENSIONS in inches (mm) Minimum/Maximum Symbol D e 28 Lead 0.378/0.386 (9.60/9.80) 0.026 BSC (0.65 BSC)
0.039 (1.0)
0'-8' 12'REF e/2 0.039 (1.0) 0.043 (1.10) Max D 0.033 (0.85) 0.037 (0.95)
0.007 (0.19) 0.012 (0.30)
0.002 (0.05) 0.006 (0.15) (2) 0.008 (0.20)
0.004 (0.09) Min
0.004 (0.09) Min Gage Plane
0.010 (0.25)
(3) 1.0 REF
0.020 (0.50) 0.026 (0.75)
(1)
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
(c) Copyright 2003 Sipex Corporation
19
ORDERING INFORMATION

Model SP3238ECA SP3238ECY SP3238EEA SP3238EEY
Temperature Range 0C to +70C 0C to +70C
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 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: sales@sipex.com
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.
Rev. 3/20/03
SP3238E Intelligent +3.0V to +5.5V RS-232 Transceiver
20
-40C to +85C -40C to +85C

(c) Copyright 2003 Sipex Corporation

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