Holtek AN0315E Using Manual Download Page 5

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Using the HT45FH3T in the Active 3D Glasses

IR Receiver Circuit

The schematic is shown below:

OPA

CMP

TO MCU

15pF

200k

15pF

4.7nF

7.15k

VDD

330pF

Amplify and filter the
tiny current generated
by the IR Photodiode

Filter the amplified signal
with a negative half cycle
and add a base level

Two signals input to the
CMP - a digital signal is
output to the MCU

Summary of Contents for AN0315E

Page 1: ...of 3D glasses is to receive and decode the IR signals from the TV for 3D glasses control Due to the high voltage driving requirement a boost circuit is needed to increase the battery voltage to 10V 12...

Page 2: ...x 2 HT45FH3T Active 3D Glasses Main Features HT45FH3T Basic Features Operating Voltage 2 2V 5 5V 4MHz System Clock HIRC 4MHz Multi mode operation NORMAL SLOW IDLE and SLEEP Flash Program Memory 2K 16...

Page 3: ...LCD lenses Provides a battery charging indicator LED Y and a low voltage indicator LED R Provides a button for glasses on off control Operating current about 680 A Three stage power saving mode First...

Page 4: ...ed to boost the battery voltage to the LCD lenses switch voltage N MOS Used for inductor booster control Lithium battery A lithium battery with a capacity of 100mAh Battery control circuit Used for th...

Page 5: ...own below OPA OPA CMP TO MCU 15pF 200k 15pF 4 7nF 2k 2k 7 15k VDD 3M 330pF Amplify and filter the tiny current generated by the IR Photodiode Filter the amplified signal with a negative half cycle and...

Page 6: ...generate an external interrupt via INT1 PA6 and turn off the power via PA1 Charging IC Circuit Use an IN4054 for lithium battery charging Setup R13 to be 10K so that a 100mA constant current can be us...

Page 7: ...pplied by the boost circuit increase the LCD control voltage to 10V for the lens on off control Battery Voltage Detect Circuit Use the ADC to check the MCU internal band gap voltage and select the ADC...

Page 8: ...ng together with IR signals with no carrier to implement decode operation and control the LCD lenses Note that LCD lenses must be properly controlled to avoid the liquid crystals remaining at the same...

Page 9: ...Using the HT45FH3T in the Active 3D Glasses 9 PCB Layout Main Board Front Back...

Page 10: ...Using the HT45FH3T in the Active 3D Glasses 10 Receiver Board...

Page 11: ...NC 0603 1 R7 360K 0603 1 R9 R10 470 0603 2 R11 470K 0603 1 LED D4 D5 Red Yellow 0603 2 Inductor L1 100uH SMD 1 N MOSFET Q1 Q2 AO3400 SOT23 2 P MOSFE Q3 AO3401 SOT23 1 Diode D1 D2 D3 BAT54 SOD232 3 Bu...

Page 12: ...Using the HT45FH3T in the Active 3D Glasses 12 Software Flowchart Main Architecture Flowchart...

Page 13: ...Using the HT45FH3T in the Active 3D Glasses 13 LCD Lenses Flowchart...

Page 14: ...the Active 3D Glasses 14 Demo Board Pictures Conclusions As the demand for 3D glasses products is increasing the HT45FH3T can be used to reduce additional circuit requirements and PCB area thus reduc...