MC145012 데이터 시트보기 (PDF) - Motorola => Freescale

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MC145012

Photoelectic Smoke Detector IC with I/O and Temporal Pattern Horn Driver

Motorola => Freescale 

MC145012

Freescale Semiconductor, Inc.

CALIBRATION

To facilitate checking the sensitivity and calibrating smoke

detectors, the MC145012 can be placed in a calibration

mode. In this mode, certain device pins are controlled/recon-

figured as shown in Table 1. To place the part in the calibra-

tion mode, Pin 16 (Test) must be pulled below the VSS pin

with 100 µA continuously drawn out of the pin for at least one

cycle on the OSC pin. To exit this mode, the Test pin is

floated for at least one OSC cycle.

In the calibration mode, the IRED pulse rate is increased to

one for every OSC cycle. Also, Strobe is always active low.

Description

Pin

I/O

7

Low--Supply Trip

15

Feedback

10

OSC

12

Silver

9

Brass

8

Table 1. Configuration of Pins in the Calibration Mode

Comment

Disabled as an output. Forcing this pin high places the photo amp output on Pin 1 or 2, as determined by

Low--Supply Trip. The amp’s output appears as pulses and is referenced to VDD etc.

If the I/O pin is high, Pin 15 controls which gain capacitor is used. Low: normal gain, amp output on Pin 1.

High: supervisory gain, amp output on Pin 2.

Driving this input high enables hysteresis (10% gain increase) in the photo amp; Pin 15 must be low.

Driving this input high brings the internal clock high. Driving the input low brings the internal clock low. If

desired, the RC network for the oscillator may be left intact; this allows the oscillator to run similar to the

normal mode of operation.

This pin becomes the smoke comparator output. When the OSC pin is toggling, positive pulses indicate

that smoke has been detected. A static low level indicates no smoke.

This pin becomes the smoke integrator output. That is, 2 consecutive smoke detections are required for

“on” (static high level) and 2 consecutive no--detections for “off” (static low level).

DO NOT RUN ANY

ADDITIONAL TRACES

IN THIS REGION

PIN 16 PIN 1

C1

R14

R11

R8

D2

MOUNTED IN

CHAMBER

PIN 9 PIN 8

NOTES: Illustration is bottom view of layout using a DIP. Top view for SOIC layout is mirror image.

Optional potentiometer R9 is not included.

Drawing is not to scale.

Leads on D2, R11, R8, and R10 and their associated traces must be kept as short as possible.

This practice minimizes noise pick up.

Pin 3 must be decoupled from all other traces.

Figure 6. Recommended PCB Layout

10

For More Information On This Product, Motorola Sensor Device Data

Go to: www.freescale.com

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