mc145010

fpgiovanini — Thu, 18 Sep 2025 21:18:45 GMT

According Figure 8. Typical Battery-Powered Application in the MC145010 DATASHEET.

There is no reflection inside the chamber but sunddenly the LED start blinking several times nonetheless the output I/O was not triggered.

which conditions make the LED this behaviour?

where this information is available?

Re: mc145010

JozefKozon — Fri, 19 Sep 2025 08:43:43 GMT

Dear fpgiovanini,

the LED can blink under several conditions not related to smoke detection:

Low-Supply Voltage Condition:
- The chip periodically checks the supply voltage using a pulsed load current from the LED pin.
- If the voltage drops below a threshold (set by external resistors), the LED flashes alongside a beep or chirp to indicate low battery.
Degraded Chamber Sensitivity:
- The IC performs periodic checks for chamber sensitivity degradation.
- A beep occurring halfway between LED flashes indicates this condition.
Push Button Test Mode:
- If the test button is pressed, the IC enters high-gain mode and may cause the LED to blink as part of the test sequence.
Power-On Reset or Internal Monitoring:
- Upon power-up or during standby, the IC may perform internal checks that momentarily activate the LED.

With Best Regards,

Jozef