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MC145012ED データシート(PDF) 9 Page - Freescale Semiconductor, Inc |
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MC145012ED データシート(HTML) 9 Page - Freescale Semiconductor, Inc |
9 / 14 page Sensors Freescale Semiconductor 9 MC145012 Figure 8. Typical Battery-Powered Application Table 4. Pin Description Pin No. Pin Name Description 1 C1 A capacitor connected to this pin as shown in Figure 8 determines the gain of the on-chip photo amplifier during push- button test and chamber sensitivity test (high gain). The capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during push-button test. Av ≈ 1 + (C1/10) where C1 is in pF. CAUTION: The value of the closed-loop gain should not exceed 10,000. 2 C2 A capacitor connected to this pin as shown in Figure 8 determines the gain of the on-chip photo amplifier except during push-button or chamber sensitivity tests. Av ≈ 1 + (C2/10) where C2 is in pF. This gain increases about 10% during the IRED pulse, after two consecutive local smoke detections. Resistor R14 must be installed in series with C2. R14 ≈ [1/(12√C2)] - 680 where R14 is in ohms and C2 is in farads. 3 DETECT This input to the high-gain pulse amplifier is tied to the cathode of an external photodiode. The photodiode should have low capacitance and low dark leakage current. The diode must be shunted by a load resistor and is operated at zero bias. The Detect input must be AC/DC decoupled from all other signals, VDD, and VSS. Lead length and/or foil traces to this pin must be minimized, also. See Figure 9. D2 IR Detector 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 TEST LOW-SUPPLY TRIP VSS R1 OSC LED FEEDBACK SILVER VDD IRED I/O BRASS STROBE DETECT C1 C2 Horn X1 To Other MC145012(s), Escape Light(S), Auxiliary Alarm(S), Remote Alarm(S), And/or Auto-dialer IR Current R13(10) 4.7 TO 22 Q1 2.2 M R5(9) D4 Visible LED R7 47 k R6 100 k SW1 + + MC145012 Reverse Polarity Protection Circuit Pushbutton Test R2 7.5 M 0.01 µF C6(9) C3 1500 pF R1 100 k R3 470 R4(9) 100 k 9 V B1 D1 1 TO 22 µF C4(12) C1 0.047 µF C2(10) 4700 pF R14 560 Ω R11 250 k R8 8.2 k R9(11) 5 k R10 4.7 k D3 IR Emitter R12 1 k C5 100 µF 9. Values for R4, R5, and C6 may differ depending on type of piezoelectric horn used. 10.C2 and R13 are used for coarse sensitivity adjustment. Typical values are shown. 11.R9 is for fine sensitivity adjustment (optional). If fixed resistors are used, R8 = 12 k, R10 is 5.6 k to 10 k, and R9 is eliminated. When R9 is used, noise pickup is increased due to antenna effects. Shielding may be required. 12.C4 should be 22 µF if B1 is a carbon battery. C4 could be reduced to 1 µF when an alkaline battery is used. |
同様の部品番号 - MC145012ED |
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同様の説明 - MC145012ED |
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