MC145012EG

Sensor And Detector Interfaces Overview

The MC145012EG is a CMOS photoelectric smoke detector integrated circuit designed for battery-powered applications. It operates within a supply voltage range of 6.0 V to 12 V, with an average standby supply current of 8 µA and a peak current of 3.0 mA during strobe pulses. The device supports an operating temperature range of -10 °C to 60 °C. It features a variable-gain photo amplifier, temporal pattern horn driver, and I/O pin for interconnecting up to 40 units. The EG suffix indicates lead-free packaging in a 16-lead SOICW package.

Sensor And Detector Interfaces Feature Summary

• Variable-gain photo amplifier interfaces directly with IR detectors using external capacitors to set gain levels for standby, local smoke, and test modes.
• I/O pin enables wired-OR common signaling for up to 40 interconnected units and can activate auxiliary devices like escape lights or auto-dialers.
• On-chip push-pull drivers control external piezoelectric transducers to produce pulsating audible alarms and chirps for low-supply or sensitivity warnings.
• Low-supply detection circuitry performs periodic checks using pulsed load current from the LED pin to monitor battery health without affecting smoke detection.

Sensor And Detector Interfaces Applications

• Battery-powered photoelectric smoke detectors complying with UL217 and UL268 specifications
• Interconnected fire alarm systems requiring common signaling across multiple units
• Emergency evacuation signal systems supporting NFPA 72, ANSI S3.41, and ISO 8201 standards

Sensor And Detector Interfaces Procurement Notes

Verify the ordering suffix 'EG' confirms lead-free packaging status as specified in the datasheet. Confirm the package type matches the required 16-lead SOICW form factor. Ensure the application environment stays within the specified -10 °C to 60 °C operating temperature range. Check that the supply voltage remains between 6.0 V and 12 V for proper operation.

Sensor And Detector Interfaces Selection Notes

Select this component for designs requiring low-power CMOS smoke detection with integrated horn driving capabilities. Consider the need for external components such as photodiodes, IR emitters, and piezoelectric transducers. Evaluate the requirement for multi-unit interconnection via the I/O pin if system-wide signaling is needed. Verify compatibility with existing PCB layout constraints for the SOICW package.

Sensor And Detector Interfaces Part Context

The MC145012 series includes variants like MC145012P (DIP) and MC145012DW (SOIC). The EG suffix specifically denotes the lead-free version of the SOICW package. This IC is part of Freescale Semiconductor's sensor portfolio, now under NXP USA Inc., focusing on safety and security applications.

Sensor And Detector Interfaces Replacement Considerations

MC145012DW: Standard SOICW package variant. MC145012P: Plastic DIP package variant. MCZ145012EG/R2: Lead-free SOICW variant in tape and reel packaging.

Sensor And Detector Interfaces FAQ

How does the MC145012 handle low-supply conditions?

The IC performs periodic low-supply tests using pulsed load current from the LED pin. If the supply drops below the threshold set by external resistors, it triggers a chirp sound and LED flash, but smoke detection continues if VDD is at least 6.0 V.

What is the function of the I/O pin?

The I/O pin allows interconnection of up to 40 units for common signaling. It can also be used to activate escape lights, auxiliary alarms, remote alarms, or auto-dialers. It features an on-chip current sink for noise immunity when used as an input.

How is the gain of the photo amplifier determined?

Gain is set by two external capacitors, C1 and C2. C1 determines high gain for push-button tests and chamber sensitivity checks, while C2 sets the gain for normal standby and local smoke conditions. The gain formula is approximately Av ≈ 1 + (C/10) where C is in pF.