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Using the HT45FH3T in the Active 3D Glasses

Circuit Description

Battery Control Circuit

The MCU can use PA1 to control the battery. When powered off, the user can press the

button to turn on the power. When powered on, the MCU must keep PA1 high to ensure

Q3 remains on. After the power is turned on, when the user press the button, the MCU

will 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 used.

OVP Function Settings

Connect the OVP pin to the voltage dividing circuit which is output from the boost circuit.

Setup the internal D/A reference voltage to come from VDD. Write a proper value to

OVOREF[5:0] bits. When the boost circuit outputs a low voltage, the OUTH pin will

automatically output a PWM signal to increase the boost voltage.

Содержание AN0315E

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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

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

Страница 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...

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

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

Страница 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...