SMOKE DETECTOR. M75210 Datasheet

M75210 DETECTOR. Datasheet pdf. Equivalent

Part M75210
Description COST-EFFECTIVE PHOTOELECTRIC SMOKE DETECTOR
Feature MOSDESIGN SEMICONDUCTOR CORP. COST-EFFECTIVE PHOTOELECTRIC SMOKE DETECTOR SMOKE DETECTOR M75210 G.
Manufacture MOSDESIGN
Total Page 8 Pages
Datasheet
Download M75210 Datasheet



M75210
一華半導體股份有限公司
MOSDESIGN SEMICONDUCTOR CORP.
COST-EFFECTIVE PHOTOELECTRIC SMOKE DETECTOR
SMOKE DETECTOR
M75210
GENERAL DESCRIPTION
The M75210 is a very low-power IC providing all of the required features for a photoelectric type smoke detector. It is
designed for operate at supply voltage as low as 2.7V and suited to 3V Lithium battery powered application. A variable-gain
photo amplifier can be directly interfaced to an infrared emitter / detector pair. The amplifier gain levels are determined by
two external capacitors that are then internally selected depending on the operating mode. Low gain is selected during standby.
During a local alarm this low gain is increased (internally) by ~ 10% to reduce false triggering. High gain is used during the
push-button test and during standby to periodically monitor the chamber sensitivity. The internal oscillator and timing
circuitry keeps standby power to a minimum by sensing for smoke every 10 seconds in a 100 μs window.
FEATURES
Operating voltage range 2.7V ~ 5V
Local or Remote Smoke Alarm output.
Low-Battery Trip Point Set Externally
Power-on Reset.
Built-in circuits to reduce false triggering.
Average Supply Current: 4μA @VDD=3.0V
ESD-Protection circuitry on all pins.
APPLICATIONS
Smoke detector.
PIN ASSIGNMENT
M75210P
C1 1
C2
DETECT
STROBE
VDD
IRED
I/O
OSCH
8
16 TEST
TRIP
VSS
OSCR
OSCC
LED
OPT
9 HORN
Pb
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M75210
一華半導體股份有限公司
MOSDESIGN SEMICONDUCTOR CORP.
COST-EFFECTIVE PHOTOELECTRIC SMOKE DETECTOR
SMOKE DETECTOR
M75210
PIN AND CIRCUIT DESCRIPTION
Pin No Pin Name
Description
A capacitor connected to this pin determines the gain of the photo amplifier during the push-to-test mode and
1
C1
during the chamber monitor test. A typical value for this high-gain mode is 0.047μF but should be selected
based on the photo chamber background reflections reaching the detector and the desired level of sensitivity.
Ae 1 + ( C1 / 10 ) where C1 is in pF. Ae should not exceed 10,000.
A capacitor connected to this pin determines the gain of the photo amplifier during standby. A typical value for
2
C2
this low-gain mode is 4700pF but should be selected based on a specific photo chamber and the desired level of
sensitivity to smoke.
Ae 1 + ( C2 / 10 ) where C2 is in pF. Ae should not exceed 10,000.
3
DETECT
This is the input to the photo amplifier and is connected to the anode of the photo
operated at zero bias and should have low dark leakage current and low capacitance.
diode.
The
photo
diode
is
This output provides a strobed , regulated voltage of 2V. The plus side of all internal and external photo amplifier
4 STROBE circuitry is referenced to this pin.
5 VDD This pin is connected to the most-positive supply potential and can range from 2.7V to 5V with respect to VSS.
This output provides a pulsed base current for the external NPN transistor, which drives the IR emitter. The NPN
6 IRED transistor’s beta should be greater than 100. To minimize noise impact, the IRED output is not active when the
horn and visible LED outputs are active.
A connection at this pin allows multiple smoke detectors to be interconnected. If a local smoke condition occurs,
this pin is driven high. As an input, this pin is sampled nominally every 1.35 seconds during standby. Any
7 I/O local-alarm condition causes this pin to be ignored as an input.
This pin also has an on-chip pull-down resistor and must be left unconnected if not used. In application, there is a
series current-limiting resistor to other smoke alarms.
8 OSCH Low-cost RC oscillator and sets the internal alarm frequency.
9
HORN
A continuous modulated tone indicates either a local or remote alarm condition. A short ( 10ms ) chirp indicates a
low-battery chirp occurs almost simultaneous with the visible LED flash.
10 OPT OPT select stand-by Led flash cycle , when connect to VSS=43 second , when connect to VDD=8 second
This open-drain NMOS output is used to directly drive a visible LED. The LED also indicates detector status as
11
LED
follows (with component values as in the typical application , all times nominal)
Standby Pulses every 43 seconds.
Test Mode Pulses every 0.67 seconds.
Local Smoke Pulses every 0.67 seconds.
Remote Alarm No pulses.
A capacitor between this pin and VDD, along with a parallel resistor, forms part of a two-terminal oscillator and
12 OSCC sets the internal clock low time. With component values as shown, this nominal time is 11 ms and essentially the
oscillator period.
13
OSCR
A resistor between this pin and OSCC (pin 12) is part of the two-terminal oscillator and sets the internal clock
high time, which is also the IRED pulse width. With component values as shown , this nominal time is 105μs .
14 VSS This pin is connected to the most negative supply potential (usually ground).
This pin is connected to an external voltage which determines the low-supply alarm threshold. The trip voltage is
15 TRIP obtained through a resistor divider connected between the VDD and LED pins. The low-supply alarm threshold
voltage ( in volts ) ( 1.4*R13/R14 ) + 1.4 where R13 and R14 are in the same units.
This pin has an internal pull-down device and is used to manually invoke a test mode. The Push-to-Test Mode is
initiated by a high logic level on this pin ( usually the depression of a normally open push-button switch to
VDD). After one oscillator cycle, IRED pulse every 336 ms ( nominal ) and amplifier gain is increased by internal
selection of C1. Background reflections in the smoke chamber can be used to simulate a smoke condition. After
16 TEST the second IRED pulse , a successful test ( two consecutive simulated smoke conditions ) activates the horn drivers
and the I/O pin. When the push-button is released , the input returns to VSS due to the internal pull down. After
one oscillator cycle , the amplifier gain returns to normal and after two additional IRED pulse ( less than one
second ) , the device exits this mode and returns to standby.
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