Infrared Transmitter and Receiver Block Design 3/29/05 Kevin Erickson

IR Transmitter Block Architecture Infrared Emitter Driver 16 bit serial data sent via Infrared Emitter Digital Audio sampled at 44.1 kHz 16 bit serial data ADC Block 0 1 0 1 0 1 0 The input is a series of 0’s and 1’s from the ADC block. The output is infrared pulses of the 0’s and 1’s sent to a photodiode in the IR Receiver 3/29/05 Kevin Erickson

IR Transmitter Schematic 5 Volt supply to operate provided by transmitter power supply block Digital audio data input from ADC block D1 is an infrared emitting diode R1 is a current limiting resistor thru the infrared emitter C1 is a speed up capacitor 2 circuits needed (left and right channel) 3/29/05 Kevin Erickson

IR Transmitter Key Component Selection Infrared emitter Ability to transmit 20 feet (high forward current) Fast switching time Current limiting resistor Power and heat dissipation Transistor Ability to handle short bursts of 1A 3/29/05 Kevin Erickson

Infrared Transmitter Key Components HDSL-4420 Infrared Emitter Characteristics Peak Forward Current (pulse width 100μs): 500 mA Continuous DC Forward Current: 100 mA Power Dissipation: 100 mW Transient Forward Current (10 ms Pulse): 1.0 A Forward Voltage: 1.30 – 1.70 V Reverse Voltage: 5 – 20 V Series Resistance: 2Ω Viewing Angle: 24° (±12°) Peak Wavelength: 850 – 900 nm Optical Rise and Fall time: 40 ns Bandwidth: 9 MHz 3/29/05 Kevin Erickson

IR Transmitter Key Component Selection Current Limiting Resistor 20Ω carbon film resistor ½ Watt 3/29/05 Kevin Erickson

IR Transmitter Key Component Selection 2N7002 N-Channel Enhancement Mode FET ID Maximum Drain Current – Continuous 115 mA – Pulsed 800 mA PD Maximum Power Dissipation: 200 mW VDS(ON) Drain-Source On-Voltage: 0.09 – 1.5 V ID(ON) On-State Drain Current: 500 – 2700 mA ton Turn-On Time: 20 ns toff Turn-Off Time: 20 ns 3/29/05 Kevin Erickson

Infrared Transmitter Bill of Materials Item # Qty Manufacture ID Number Attributes Reference to Schematic Cost 1 2 Agilient HSDL-4420 Infrared emitter--880nm Peak emission ±12° Half angle 40ns Switching times D1 $1.32 Kemet C315C473M5U5CA 0.047 μf Capacitor 50 Volt ± 10% tolerance C1 $0.36 3 Yageo CFR-50JB-20R 20 Ohm carbon film resistor ½ Watt 1% tolerance R1 $0.02 4 CFR-25JB-1K0 1 kΩ Ohm carbon film resistor ¼ Watt ± 5% tolerance R2 5 CFR-25JB-22R 22 Ohm carbon film resistor R3 6 Fairchild Semi 2N7002 N-Channel Enhancement Mode FET Power MOSFET gate drivers 10ns Switching times Q1 $0.50 Total $2.24 3/29/05 Kevin Erickson

IR Receiver Block Architecture 16 bit serial data sent via Infrared Emitter 16 bit serial data to DAC block Photodiode Transimpedance Amplifier Comparator DAC 0 1 0 1 0 1 0 Photodiode receives the infrared signal and converts the light signal to current The transimpedance amplifier is needed to convert the current into an amplified voltage Comparator is used to create the 5 Volt logic (0’s and 1’s) needed by the ADC block 3/29/05 Kevin Erickson

IR Receiver Schematic Transimpedance Amplifier Comparator Photodiode 2 circuits needed (left and right channel) Transimpedance Amplifier Comparator Photodiode D1 is a photodiode (λ=880-950nm) U1 creates the transimpedance amplifier U2 is a 5V comparator for 5V logic. 3/29/05 Kevin Erickson

IR Receiver Key Component Selection Photodiode Fast switching time Able to receive infrared signal 20 feet away Comparator 0-5 Volt logic output 3/29/05 Kevin Erickson

Infrared Transmitter Key Components HDSL-5420 Photodiode Characteristics Short Circuit Current: 4.3 μA PhotoCurrent: 3.0 – 6.0 μA Power Dissipation: 150 mW Forward Voltage: 0.8 V Series Resistance: 2000Ω Viewing Angle: 28° (±14°) Peak Wavelength: 850 – 900 nm Optical Rise and Fall time: 7.5 ns Bandwidth: 50 MHz 3/29/05 Kevin Erickson

IR Receiver Transimpedance Amplifier Typical ISC = 4.3μA from photodiode spec. sheet ISC 3/29/05 Kevin Erickson

Infrared Receiver Bill of Materials Item # Qty Manufacture ID Attributes Reference to Schematic Cost 1 2 HSDL-5420 875nm Peak emission ±14° Half angle 7.5ns Switching times D1 $1.08 LM741CN General purpose op-amp U1 3 LMV331 5 Volt Comparator 5V logic output U2 $1.60 4 CFR-25JB-1M0 1 MΩ Ohm carbon film ¼ Watt ± 5% tolerance R1 $0.02 Total $3.78 3/29/05 Kevin Erickson