Hi Federico， Sorry for late. I'd like to summarize your remained questions as below: 1. But in the data sheet of MFP430FR2311 there's not electric specification for DAC... is it missing or didn't see it? [Reply]: Some electric specifications for 6-bit DAC are not released. 2. I hope we will plan the 32 pin version! More pins are always useful!!! Some example that brings me to use the 20pin version: * 2-3 pin for 2-wires digital communication to control panel (1: tx, 1 edge rx and, if need 1 level rx) * 1-2 for for led indication (now I have only one led, but it's not enough) * 1-2 pin for NTC heat sensor (1 pin if I power NTC at 3,3V or share it to parts of circuits; in the first release: 1 pin to power NTC and 1 pin to read the value) * 2 pin for I2C for other use (not need for this version, but it's my hope to have it) * 2-3 pin for additional sensor, such as CO * 2 pins if I have the loop isolator inside 5nA such as Ibias is enormous value when I use a photodiode! Considering that TRIO- not multiplexed is 50pA, but it's not enough! In my original circuit, that work well (certified in according to EN54), the external operational has 1pA that increase to 20pF at t=+85°C! it's clear that to have 50pF is too much to read the value and distinguish the these value when IR led is in ON and in OFF. Instead using a external operational amplifier I can distinguish very very well. So, It's not possible to use the internal TIA connected directly to ADC, as suggested in the example. The TIA for a real smoke detection is not good and not enough! I will try to use a integrator, but the BOM is increased. If You really want to make a chip for smoke detection, eh, ask to the person the work to smoke detector and have experienced to laboratory certification and certificate! I hope You have a plan for a new good chipo for real smoke detection... For example, it needs to add the integrator... [Reply]: Thanks for sharing your experience. We will consider your suggestions in our future products. But MSP430FR2311 and MSP430FR235x have many successful examples in our smoke detector customers. So, if 50pA Ibias is not enough, TI still has many 1pA-level operation amplifier products. 3. If You want to make a new chip for smoke (heat and CO) detection for addressable fire system, it's better to ask to who has real experience and make a partnership! For example, I'm available... ;-) [Reply]: Again, thanks for sharing your experience. We will consider your suggestions in our future products. Best Regards, Winter Yu
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