5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
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19-1402; 11/98
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
MAX3130/MAX3131 combine IrDA compatible infrared transceiver with RS-232 interface-all single 3V-powered hybrid microcircuit. infrared transceiver supports IrDA data rates 2.4kbps 115kbps. infrared receive channel provides highgain/low-noise PIN-diode amplifier with 100µA ambient photodiode current rejection supply. high-power driver capable sinking 200mA included infrared transmit path. on-board encoder/decoder (ENDEC) compresses/stretches signals from external UART, allowing IrDA communication even with non-IrDA UARTs. 2-driver/2-receiver RS-232 transceiver supports data rates 120kbps. proprietary, high-efficiency, dual charge-pump power supply low-dropout transmitter combine deliver true RS-232 performance from single +3.0V +5.5V supply. Selectable shutdown RS-232 circuitry reduces supply current 1µA. MAX3130 optimized applications using single UART both infrared RS-232 communication. infrared transmitter input infrared receiver output multiplexed with RS-232 transmitter input RS-232 receiver output, respectively. MAX3131's IrDA transceiver RS-232 transceivers separate have their data inputs outputs. Both these devices require minimum external components: four small 0.1µF capacitors, photodiode, infrared LED, current-setting resistor.
Features
Integrated RS-232 IrDA Single 28-Pin SSOP Package 370µA Supply Current IrDA Compatible: 2.4kbps 115kbps Data Rate On-Board Encoder/Decoder Allows Non-IrDA UARTs +3.0V +5.5V Single-Supply Operation Meet EIA/TIA-232 Specifications Down 200mA, High-Current Infrared Drive Low-Power Shutdown with RS-232 Receivers Active
MAX3130/MAX3131
Ordering Information
PART MAX3130CAI MAX3130EAI MAX3131CAI MAX3131EAI TEMP. RANGE +70°C -40°C +85°C +70°C -40°C +85°C PIN-PACKAGE SSOP SSOP SSOP SSOP
Configuration
VIEW
EDGEDET (RXD) R2OUT R2IN T2OUT RSSD
Applications
Personal Digital Assistants (PDAs) Palmtop Computers Battery-Powered Systems Hand-Held Equipment Peripherals IrDA Applications Cellular Phones
T1IN T2IN IRMODE (TXD) R1OUT R1IN T1OUT BAUD16 N.C. AVCC AGND PINC
MAX3130 MAX3131
C222 C120 N.C. LEDC PGND IRSD
MAX3131
SSOP
Maxim Integrated Products
free samples latest literature: http://www.maxim-ic.com, phone 1-800-998-8800. small orders, phone 1-800-835-8769.
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
ABSOLUTE MAXIMUM RATINGS
.-0.3V AVCC AGND .-0.3V AVCC .±0.3V AGND, PGND .±0.1V .-0.3V .+0.3V .+13V Inputs (referenced GND) T1IN, T2IN, TXD, RSSD, IRMODE, BAUD16, IRSD.-0.3V R1IN, R2IN .±25V Outputs (referenced GND) T1OUT, T2OUT.±13.2V R1OUT, R2OUT, EDGEDET, RXD.-0.3V (VCC 0.3V) LEDC.-0.3V Output Short-Circuit Duration GND) T1OUT, T2OUT .Continuous Output Currents LEDC Continuous .200mA LEDC Duty Cycle 90µs.500mA Input Current PINC .10mA Continuous Power Dissipation +70°C) SSOP (derate 9.52mW/°C above +70°C) .762mW Operating Temperature Ranges MAX3130/MAX3131CAI .0°C +70°C MAX3130/MAX3131EAI.-40°C +85°C Storage Temperature Range .-65°C +160°C Lead Temperature (soldering, 10sec) .+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC AVCC 3.0V 5.5V, AGND PGND, C1-C4 0.1µF (Note TMIN TMAX, unless otherwise noted. Typical values +25°C AVCC 3.3V.) PARAMETER CHARACTERISTICS Power-Supply Current Analog Power-Supply Current Shutdown Supply Current Shutdown Analog Supply Current 3.3V +25°C (Note +25°C (Note RSSD IRMODE low, +25°C (Note IRSD low, +25°C (Note 0.25 0.01 CONDITIONS UNITS
LOGIC INPUTS (T1IN, T2IN, TXD, IRMODE, BAUD16, IRSD, RSSD) Input Logic Threshold Input Logic Threshold High Input Leakage Current AVCC 3.3V AVCC ISINK 1.6mA ISOURCE 1.0mA (Note AVCC 3.3V AVCC 0.0002 ±0.01 ±1.0
LOGIC OUTPUTS (R1OUT, R2OUT, RXD, EDGEDET) Output Voltage Output Voltage High RECEIVER Data Rate Equivalent Input Noise Current Input Current Sensitivity Ambient Photodiode Current Rejection (Note 115.2 kbps nARMS 0.05
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
ELECTRICAL CHARACTERISTICS (continued)
(VCC AVCC 3.0V 5.5V, AGND PGND, C1-C4 0.1µF (Note TMIN TMAX, unless otherwise noted. Typical values +25°C AVCC 3.3V.) PARAMETER Receiver Disable Time Receiver Enable Time Receiver Output Pulse Width TRANSMITTER Transmitter Rise Time Transmitter Fall Time Transmitter Output Resistance Off-Leakage Current IrDA ENCODER/DECODER (ENDEC) Maximum Operating Frequency Output Pulse Width BAUD16 Operating Frequency Range RS-232 RECEIVER Input Voltage Range Input Threshold Input Threshold High Input Hysteresis Input Resistance Receiver Propagation Delay Receiver Skew RS-232 TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current Maximum Data Rate Transmitter Skew T1OUT, T2OUT, loaded with T_OUT VT_OUT VT_OUT ±12V, 5.5V, RS-232 transceiver shutdown 1000pF, transmitter switching tPHL tPLH ±5.4 kbps +25°C R_IN R_OUT, 150pF tPHL tPLH, 150pF tPHL tPLH 3.3V 3.3V Maximum frequency BAUD16 fBAUD16 1.8432MHz, measured VLEDC fBAUD16 required enable ENDEC 1.43 34.6 2.23 2000 200mA drive current 200mA drive current IOUT 200mA VLEDC 5.5V AVCC 3.3V AVCC 1.15 0.01 10.0 CONDITIONS Delay until IAVCC Delay until maximum receive data rate valid BAUD16 static (Note Data rate 2.4kbps Data rate 115kbps UNITS
MAX3130/MAX3131
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
ELECTRICAL CHARACTERISTICS (continued)
(VCC AVCC 3.0V 5.5V, AGND PGND, C1-C4 0.1µF (Note TMIN TMAX, unless otherwise noted. Typical values +25°C AVCC 3.3V.) PARAMETER CONDITIONS 3.3V, measured from +3V, +25°C 150pF 1000pF 150pF 2500pF V/µs UNITS
Transition-Region Slew Rate
Transmitter Enable Time
Delay until transmitter outputs valid
Note C1-C4 0.1µF, tested +3.3V ±10%. 0.047µF, C2-C4 0.33µF, tested +5.0V ±10%. Note supply current measurements made under no-load condition outputs, input voltages GND. Note compliant IrDA input signal where data rate within supported data rate receive mode: rise/fall times less than 600ns pulse widths between 1.41µs 3/16 baud rate.
Typical Operating Characteristics
(VCC AVCC 3.3V, AGND PGND, C1-C4 0.1µF, +25°C, unless otherwise noted.)
ANALOG SUPPLY CURRENT TEMPERATURE
MAX3130 toc02 MAX3130 toc01
SUPPLY CURRENT TEMPERATURE
IAVCC (µA) (µA) TEMPERATURE (°C) 3.3V
AMBIENT PHOTODIODE CURRENT REJECTION SUPPLY VOLTAGE
MAX3130 toc03
AVCC
CURRENT REJECTION (µA)
AVCC 3.3V
TEMPERATURE (°C) SUPPLY VOLTAGE
DRIVER ON-RESISTANCE TEMPERATURE
MAX3130 toc04
LEDC VOLTAGE LEDC CURRENT
MAX3130 toc05
OUTPUT PULSE WIDTH DISTANCE (2400bps)
TRANSMITTER POWER 200mW/sr INPUT PULSE WIDTH 78µs TEMIC BPV22NF 3.3V
MAX3130 toc06
RLED ILEDC 200mA 3.3V
LEDC VOLTAGE (mV) 3.3V
PULSE WIDTH (µs)
PULSED DUTY CYCLE
LEDC CURRENT (mA) DISTANCE (cm)
TEMPERATURE (°C)
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Typical Operating Characteristics (continued)
(VCC AVCC 3.3V, AGND PGND, C1-C4 0.1µF, +25°C, unless otherwise noted.)
OUTPUT PULSE WIDTH DISTANCE (115.2 kbps)
MAX3130 toc07
MAX3130/MAX3131
TRANSMITTER OUTPUT VOLTAGE LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE VOUT+ TRANSMITTER 235kbps TRANSMITTER 15kbps
MAX3130 toc08
PULSE WIDTH (µs)
TRANSMITTER POWER 200mW/sr INPUT PULSE WIDTH 1.63µs TEMIC BPV22NF 3.3V
1000 2000 3000
VOUT-
4000
5000
DISTANCE (cm)
LOAD CAPACITANCE (pF)
RS-232 TRANSMITTER SLEW RATE LOAD CAPACITANCE
MAX3130 toc09
SUPPLY CURRENT LOAD CAPACITANCE (RS-232 TRANSMITTING)
TRANSMITTER DRIVEN ONLY 235kbps (mA) 120kbps 20kbps
MAX3130-toc10
SLEW RATE (V/µs) 1000 2000 3000 4000 +SLEW -SLEW
5000
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
OUTPUT INFRARED INPUT
OUTPUT INFRARED INPUT
MAX3130 toc11
MAX3130 toc12
2V/div
OUTPUT
2V/div
OUTPUT
2V/div
INFRARED INPUT 2V/div
INFRARED INPUT
2µs/div 3.3V, 115.2kbps DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
100µs/div 3.3V, 2400bps DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
Typical Operating Characteristics (continued)
(VCC AVCC 3.3V, AGND PGND, C1-C4 0.1µF, +25°C, unless otherwise noted.)
OUTPUT INFRARED INPUT OUTPUT INFRARED INPUT
MAX3130 toc13
MAX3130 toc14
2V/div
OUTPUT
2V/div
OUTPUT
2V/div
INFRARED INPUT
2V/div
INFRARED INPUT
2µs/div 3.3V, 115.2kbps 10cm DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
100µs/div 3.3V, 2400bps 10cm DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
OUTPUT INFRARED INPUT
MAX3130 toc15
OUTPUT INFRARED INPUT
MAX3130 toc16
2V/div
OUTPUT
2V/div
OUTPUT
2V/div
INFRARED INPUT
2V/div
INFRARED INPUT
2µs/div 3.3V, 115.2kbps DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
100µs/div 3.3V, 2400bps DISTANCE TEMIC BPV22NF TRANSMIT POWER 200mW/sr
Description
MAX3130 MAX3131 NAME FUNCTION Edge Detector Output. EDGEDET goes activity sensed either RS-232 receiver IrDA receiver, depending state IRMODE. EDGEDET: EdgeDetection Circuitry section. Receiver TTL/CMOS Data Output TTL/CMOS RS-232 Transmitter Input
EDGEDET T1IN
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Description (continued)
MAX3130 MAX3131 NAME FUNCTION TTL/CMOS RS-232 Transmitter Input. MAX3130, drive IRMODE connect T2IN transmitter input, drive IRMODE high connect T2IN RS-232 transmitter input. MAX3131, T2IN always connected RS-232 transmitter input. Mode Control. Drive IRMODE connect R2OUT receiver output T2IN transmitter input. Driving IRMODE also shuts down RS-232 charge pump puts RS-232 transmitter outputs high-impedance state. Drive IRMODE high connect R2OUT RS-232 receiver output connect T2IN RS-232 transmitter input. Transmitter TTL/CMOS Data Input TTL/CMOS RS-232 Receiver Output RS-232 Receiver Input RS-232 Transmitter Output 16-Times Baud-Rate Input. ENDEC, apply signal that times baud rate into BAUD16. Connect BAUD16 disable ENDEC. Ground 3.0V 5.5V Supply Voltage Connection. make connections these pins. Analog Supply Voltage Signal Processing. AVCC range 3.0V 5.5V. Analog Ground Signal Processing. Connect GND. Silicon Photodiode Input. Connect PINC cathode photodiode. Connect anode photodiode GND. Shutdown Input IrDA Transceiver Circuitry Power Ground Driver. Connect GND. Open-Drain Output Driving LED. Connect LEDC cathode LED. +5.5V Generated Internal Charge Pump Positive Terminal Voltage-Doubling Charge-Pump Capacitor Negative Terminal Voltage-Doubling Charge-Pump Capacitor Positive Terminal Inverting Charge-Pump Capacitor Negative Terminal Inverting Charge-Pump Capacitor -5.5V Generated Internal Charge Pump Shutdown Input RS-232 Transmitters Charge Pump RS-232 Transmitter Output RS-232 Receiver Input TTL/CMOS RS-232 Receiver Output. MAX3130, drive IRMODE connect R2OUT receiver output, drive IRMODE high connect R2OUT RS-232 receiver output. MAX3131, R2OUT always internally connected RS-232 receiver output.
MAX3130/MAX3131
T2IN
IRMODE
R1OUT R1IN T1OUT BAUD16 N.C. AVCC AGND PINC IRSD PGND LEDC C1C2+ C2VRSSD T2OUT R2IN
R2OUT
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
MAX3130 Function Table
MAX3130 CONTROL INPUTS RSSD IRMODE IRSD LOGIC INPUTS T1IN RS-232 Input RS-232 Input T2IN IrDA Input IrDA Input T1OUT High-Z High-Z High-Z High-Z RS-232 T2OUT High-Z High-Z High-Z High-Z RS-232 Output RS-232 Output R1IN RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input R2IN RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input RS-232 Input LOGIC OUTPUTS R1OUT RS-232 Output RS-232 Output RS-232 Output RS-232 Output RS-232 Output RS-232 Output R2OUT IrDA Output IrDA Output RS-232 Output RS-232 Output RS-232 Output RS-232 Output IrDA OUTPUT LEDC Enabled Enabled Disabled Disabled Disabled Disabled IrDA INPUT PINC Disabled Enabled Disabled Enabled Disabled Enabled
RS-232 RS-232 Input Input RS-232 RS-232 Input Input
RS-232 RS-232 RS-232 Input Input Output RS-232 RS-232 RS-232 Input Input Output
Don't care
MAX3131 Operational Modes Table
RSSD IRSD T_OUT High-Z High-Z Enabled Enabled R_IN Enabled Enabled Enabled Enabled LEDC Enabled Enabled Enabled Enabled Logic High IrDA Output Logic High IrDA Output
Detailed Description
MAX3130/MAX3131 IrDA compatible, infrared transceivers with integrated RS-232 interface. selecting appropriate external optical components, these devices support IrDA data rates from 2.4kbps 115kbps distances from low-noise design allows them achieve bit-error rate below 10-8 maximum data rates. On-chip filtering rejects out-of-band ambient light signals that interfere with infrared communication. Both devices include high-power driver capable sinking 200mA. MAX3130 MAX3131 contain RS-232 drivers RS-232 receivers that support data rates 120kbps. RS-232 transceiver powered highefficiency, dual charge-pump power supply that operates with input supply voltages from +3.0V +5.5V. MAX3130 optimized applications using single UART both infrared RS-232 communication. infrared transmitter input infrared receiver output multiplexed with RS-232 transmitter input RS-232 receiver output, respectively. MAX3131 IrDA RS-232 transceivers independent each other simultaneous multiprotocol transceiver applications.
Receivers
receiver amplifier reverse biases diode with approximately 1.2V, diode converts pulses light into pulses current. input transimpedance (current-to-voltage) amplifier converts amplifies these current pulses into voltage pulses. MAX3130/MAX3131 incorporate filters that remove lowfrequency ambient light interference high-frequency circuit noise from these voltage pulses. high-speed comparator then translates these voltage pulses into CMOS output levels. Figures show system functional diagrams. output infrared receiver MAX3131. R2OUT output infrared receiver MAX3130 (IRMODE low). With ENDEC disabled, infrared receiver output pulses upon each incoming infrared pulse. pulse width receiver output depends many factors, including transmitter distance power, photodiode efficiency area, incoming data rate. Under circumstances output pulse less than baud period. communicate with UARTs that IrDA compatible, enable ENDEC (see IrDA Encoder/Decoder (ENDEC) section).
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
C1C2+ C2R1OUT RECEIVE LOGIC OUTPUTS R2OUT EDGE T1IN TRANSMIT LOGIC INPUTS IRMODE BAUD16 fBAUD16 TxIN ENDEC RxIN EDGEDET RSET T1OUT RS-232 OUTPUTS R2IN CHARGE PUMP RSSD SHDN
R1IN RS-232 INPUTS
T2IN
T2OUT
EDGE
MAX3130
LEDC
PGND PINC
IRSD
BIAS
1.2V
AVCC AGND
Figure MAX3130 Functional Diagram
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
C1C2+ C2R1OUT RS-232 RECEIVE LOGIC OUTPUTS CHARGE PUMP
SHDN RSSD
R1IN RS-232 INPUTS R2IN
R2OUT
T1IN RS-232 TRANSMIT LOGIC INPUTS IrDA TRANSMIT LOGIC INPUT IrDA RECEIVE LOGIC OUTPUT
T1OUT RS-232 OUTPUTS
T2IN TxIN ENDEC RxIN
T2OUT
MAX3131
RSET
BAUD16
fBAUD16
LEDC
PGND PINC
IRSD
BIAS
1.2V
AVCC AGND
Figure MAX3131 Functional Diagram
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Transmitter
infrared transmitter consists internal highpower, open-drain MOSFET switch. This switch on-resistance less than capable switching 200mA current. Internal buffering keeps input capacitance extremely ease user drive requirements. Connect series with current-setting resistor select appropriate output power (see Powering section). transmitter current limited exceed power dissipation external components during high duty-cycle transmit schemes. input controls MAX3131. T2IN input controls MAX3130 (IRMODE low). With ENDEC disabled (see IrDA Encoder/Decoder (ENDEC) section), turned logic-high signal T2IN input, MAX3131 MAX3130 respectively.
EDGEDET: Edge-Detection Circuitry (MAX3130)
MAX3130 internal edge-detection circuitry that monitors RS-232 R2OUT line when IRMODE monitors IrDA receive channel when IRMODE high. EDGEDET goes when positive negative edge detected either RS-232 R2OUT line IrDA receive channel (depending IRMODE pin). This edge-detection feature useful initiating interrupt when data received deselected line. EDGEDET signal cleared when IRMODE toggled. Table shows EDGEDET operation.
MAX3130/MAX3131
IrDA Encoder/Decoder (ENDEC)
MAX3130 MAX3131 provide on-board ENDEC communicate with UARTs that IrDA compatible. ENDEC enabled applying clock with frequency times baud rate BAUD16 input. This BAUD16 clock commonly provided UARTs that have IrDA ENDEC capability. Figure illustrates operation ENDEC. ENDEC stretches incoming infrared pulse pulse between
IRMODE: Multiplexed RS-232 Operation IrDA Operation (MAX3130)
MAX3130 capability multiplex R2OUT T2IN between IrDA infrared interface RS-232 electrical interface. state IRMODE input determines which interface (infrared RS-232) multiplexed R2OUT T2IN. When IRMODE low, R2OUT acts infrared receiver output T2IN acts infrared transmitter input. Also, while IRMODE low, RS-232 charge pumps shut down RS-232 transmitters disabled (see Shutdown section). When IRMODE high, R2OUT T2IN assume their functions RS-232 data receive output transmit input, respectively. Also, while IRMODE high, transmitter disabled (turned off).
Table EDGEDET Operation
IRSD RSSD IRMODE R2IN IrDA RxIN EDGEDET*
Don't care EDGEDET cleared transition IRMODE.
INFRARED PHOTODIODE INPUT 1.41µs 16CS
R2OUT (RXD) WITH ENDEC DISABLED
R2OUT (RXD) WITH ENDEC ENABLED 16CS BAUD16 CLOCK CYCLES HIGH INFRARED LIGHT PULSE MAX3131 32CS
Figure ENDEC Operation, Receiving Infrared
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
T2IN (TXD)
INFRARED OUTPUT BAUD16 CLOCK CYCLES HIGH INFRARED LIGHT PULSE MAX3131 16CS
Figure ENDEC Operation, Transmitting Infrared
three BAUD16 clock cycles) into full baud period (Figure 3a). Signals applied inverted compressed three BAUD16 clock cycles ENDEC before being transmitted (Figure 3b). ENDEC disabled connecting BAUD16 input GND.
Applications Information
Shutdown
MAX3130/MAX3131 have split analog digital supplies with separate shutdown modes. When IRSD pulled low, receiver disabled AVCC current reduces <1µA. When RSSD IRMODE pulled low, RS-232 charge pumps disabled RS-232 transmitter outputs become high impedance. this mode, current reduces <10µA.
Dual Charge-Pump Voltage Converter
MAX3130/MAX3131's internal power supply consists regulated dual charge pump that provides output voltages +5.5V (doubling charge pump) -5.5V (inverting charge pump) supply voltages from +3.0V +5.5V. charge pump operates discontinuous mode: output voltages less than 5.5V, charge pumps enabled; output voltages exceed 5.5V, charge pumps stop switching. Each charge pump requires flying capacitor (C1, reservoir capacitor (C3, generate supplies (Figures RSSD IRMODE MAX3130) low, both charge pumps shut down.
Selection
IrDA specification calls transmitter with peak wavelength between 850nm 900nm. Within ±15° half-cone angle, output intensity must between 40mW/sr 500mW/sr. Outside ±30° half-cone angle, output intensity must fall below 40mW/sr. Within these cases, optical rise fall times must less than 600ns. Based these system requirements HSDL-4220, Temic TSHF5400, equivalent LEDs appropriate choices.
RS-232 Transmitters
RS-232 transmitters inverting level translators that convert CMOS-logic levels ±5.0V EIA/TIA-232 levels. MAX3130/MAX3131 transmitters guaranteed data rates 120kbps, providing compatibility with PC-to-PC communication software, such LapLinkTM. These RS-232 transmitters typically operate data rates 235kbps. RS-232 transmitter outputs high impedance when either IRMODE RSSD low. MAX3130/MAX3131 RS-232 receivers translate RS232 signal levels CMOS-level logic. RS-232 receivers also perform logic inversion from input output. receivers always active affected RS-232 shutdown input (RSSD).
Powering
current with external resistor. Using manufacturer's data sheet, select forward current that meets IrDA specifications discussed Selection section. Determine forward bias voltage (VIRLED) voltage drop across MAX3130/MAX3131 driver (see LEDC Voltage LEDC Current graph Typical Operating Characteristics) choose current-setting resistor based following equation: RSET (VCC VIRLED VLEDC) ISET Using HSDL-4220 example: ISET 100mA, VIRLED 1.67V VLEDC 90mV RSET 1.67V 90mV) 0.1A 32.4
LapLink trademark Traveling Software.
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Power dissipation MAX3130/MAX3131, LED, RSET based maximum current duty cycle. following equations calculate power dissipation each component: MAX3130 power dissipation ISET VDRV duty cycle power dissipation ISET VIRLED duty cycle RSET power dissipation ISET2 RSET duty cycle reliable operation, exceed maximum power dissipation components. When using minimum required capacitor values, make sure capacitor value does degrade excessively with temperature. doubt, capacitors with larger nominal value. capacitor's equivalent series resistance (ESR) usually rises temperatures increases amount ripple
MAX3130/MAX3131
Power-Supply Noise Rejection
Because extremely sensitive nature photodiode amplifiers, important maintain low-noise supply voltage. separate analog supply voltage where possible. Place ceramic bypass capacitor close possible AVCC pins. especially noisy systems, connect small (10) resistor series with VCC, addition normal bypass capacitors.
Photodiode Selection
photodiode selection extremely important system performance. diode must generate least 200nA (minimum sensitivity MAX3130/MAX3131) current when aimed ±15° off-axis with incident irradiance 4µW/cm2. following equation determines Temic BPV22NF meets these requirements: IPIN (4µW/cm2 (0.075cm2) (0.95) (0.95) (1.8) (0.6A/W) 292nA first term (4mW/cm2) minimum guaranteed irradiance ±15° angular range. second term (0.075cm2) sensitive area diode. first 0.95 factor normalizes sensitivity 875nm wavelength second 0.95 factor adjusts decreased receiver efficiency ±15° off-axis. factor accounts round lens which increases effective diode area. last term (0.6A/W) sensitivity diode. Based this example, Temic BPV22NF appropriate selection. final important factor selecting diode effective diode capacitance. important keep this capacitance below 70pF 1.2V reverse bias. Higher input capacitance compromises noise performance system increasing noise gain input transimpedance amplifier.
IrDA RS-232 Application Circuit
Figure shows MAX3130 used multiplex between RS-232 IrDA communication while using only UART. using IRMODE input, type communication (infrared RS-232) controlled internal MAX3130 ENDEC used translate between UART-type IrDA-type bitstreams. UART this capability, connect BAUD16 MAX3130 GND. Figure shows MAX3131 used with UARTs perform simultaneous IrDA RS-232 communication. UART1 software UART used perform infrared IrDA communication. internal ENDEC MAX3131 translates between UART-type IrDA-type bit-streams. MAX3100 implemented UART2 communicates RS-232 interface. MAX3100 interfaces using interface.
Layout Considerations
MAX3130/MAX3131 require careful layout techniques minimize parasitic signals coupling PINC input. Keep lead length between photodiode PINC short possible. Keep board traces diode away from other noisy traces. minimize coupling, AGND trace adjacent PINC trace both sides. prevent oscillation, avoid routing trace near PINC trace. Connect anode diode, GND, ground lead AVCC bypass capacitor starconnection. Keep output pins short possible minimize coupling back input parasitic capacitance.
Capacitor Selection
capacitor type used C1-C4 critical proper operation; either polarized nonpolarized capacitors good choices. charge pump requires 0.1µF capacitors 3.3V operation. other supply voltages, refer Table suggested capacitor values. values smaller than those listed Table Increasing capacitor values (e.g., factor reduces ripple transmitter outputs slightly reduces power consumption. increased without changing C1's value. However, increase without also increasing values
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
Table Required Capacitor Values
(µF) 0.047 (µF) 0.33 0.47
STANDARD NON-IrDA UART
MAX3130
T1IN R1OUT T1OUT R1IN T2OUT R2IN LEDC IrDA PINC DB-9 RS-232
BAUD16 IrDA
T2IN R2OUT BAUD16 IRMODE
Figure Using MAX3130 Single UART Perform Both IrDA RS-232 Communication
DOUT SCLK
MAX3100 UART2
MAX3131
T1IN R1OUT T2IN R2OUT T1OUT R1IN T2OUT R2IN LEDC BAUD16 IrDA PINC DB-9 RS-232
NON-IrDA UART BAUD16
(UART1)
Figure Using MAX3131 UARTs Perform Simultaneous IrDA RS-232 Communication
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface
Chip Information
TRANSISTOR COUNT: 1039
MAX3130/MAX3131
_Package Information
SSOP.EPS
5.5V, IrDA Infrared Transceiver with Integrated RS-232 Interface MAX3130/MAX3131
NOTES
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
_Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600 1998 Maxim Integrated Products Printed registered trademark Maxim Integrated Products.
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