Independent Voice Type CO Alarm HT45F43 Characteristics MCU characteristics : internal 2x OPAs & 2x comparators, EEPROM, HIRC 4MHz + 32K LIRC reduces external component count Sensor : electro-chemical sensor (ME2-CO) Power supply : 9V alkaline battery Standby current : typ. 22A, max. 28A Low voltage detect : 7.5V Self Test / Calibrate function LEDs : red, yellow, green Voice functions for : CO level, battery low etc. Internal oscillator and reset circuitry for reduced external components Internal OPA for sensor signal amplification -- no need for external amplifier Watchdog wakes up MCU every 32 seconds -- checks CO level and battery Operating Procedure Preheat description One min. preheat time required at power on. Other operations implemented during this time generate a Beep and System Malfunction voice output. CO level measurement function WDT wake-up every 32 sec -- implements CO level check. > 30PPM alarm sounds with - Beep + Beep Beep + CO level exceeds limit for 30 sec and LED1 flashes. After 20 sec the alarm stops. Alarm cancelled by pressing key Switch activated auto test function Short press : battery test, 1.65V voltage ref. test, CO sensor open circuit test During the battery low voltage test, the alarm will emit a Beep + Please change the battery voice output and the green LED2 will flash once. If CO sensor open circuit or 1.65V voltage ref. out of range, then alarm emits a Beep + System Malfunction voice and green LED2 flashes once. If the system is operating normally, then a Beep + System Normal voice output will be generated and the red LED1 will flash once. Long switch press : voice test mode. All voice data output in sequence. Voice can be stopped by pressing switch again. Calibration function Hold the switch down and apply power to execute. Implements a 30PPM / 50PPM / 100PPM / 300PPM calibration -- yellow LED3 will flash. Flash 3 times with 0.5 sec stop indicates 30PPM calibration and so on. The switch can be used to change the calibration level. After the calibration has completed the system enters the normal operating mode. Application Circuit CO Sensor Fixed Voltage and Amplifier Circuit Test and Calibration Switch U1 5 3V3 1.65V R5 1M 100K Q1 R8 C8050 1K C1 PC1/AN5/OSC2 4 PA2/A1P 18 R7 TEST PC2/OSC3 PA2/A1P/C2OUT PA1/C1OUT/TMR0 OPA1 17 PA0/CNP/COM0 1K 1 R6 1M ME2-CO 16 C PC3/OSC4 PA4/A1E/TMR1 1K PA0 3V3 J270 33K 15 R10 51K 3 PA5/A2P/PFD Vin Vout GND 3 3V3 20 PB3/AN0/SCS PB1/SDI/SDA PB2/SCK/SCL PB0/SDO/INT1 VSS VDD PB6/AN3/RES 9 11 10 12 1 2 6 5 7 CE VDD SO HD SCK WP SI VSS 8 7 3 4 RESET C9 104 3V3 PC0/AN4/OSC1 3V3 2 8 6 4 - AudIn CE VDD OUTP NC OUTN VSS VREF 5 7 1 3 C7 V 6 1 / U 1 9 3 7 V 2 8 T H HT45F43 Battery Power Supply R1 6 U3 r e k a e p S C5 3 0 1 + 6 C8 R1 2 K 0 2 8 K 1 5 R1 5 C6 PB4/AN1/AUD/PCLK LOW_BAT 3V3 U2 V 6 1 / U 7 4 3 0 1 K 0 1 1 C4 22U /16V Voice Flash Memory 3V3 5 0 0 2 L 5 2 X M HT7533 C3 ICP Interface LED Indicators OPA2 R1 1 19 22U/35V 2 390K Calibration K 1 5 P1 R14 LED3 HT82V739 Driver Related Data Report Item ESD test report Operating current JP1 1 2 3 4 5 PA2/A1P 3V3 VSS RESET PA0 R3 C10 104 10U /16V 750K LED3 1K 13 PA7/A2E/BZB C2 R13 Bat/Error R2 14 PA6/A2N/BZ 9V LED2 R9 W D2 1N4148 Alarm R1 2 PA3/A1N/INT0 10uF 3V3 LED1 Type Result CONTACT type 10kV no reset or system crash AIR type 16kV no reset or system crash Typ. standby current 22A Max. standby current 28A Alarm operating current Less than 50mA