BL59A66 datasheet 1. intr oduction: t h e bl 59a66 is a l o w-curre nt bicmos circu it p r ov id ing all o f th e featu r es for a pho to electri c t y pe sm oke de t ect or. b l 5 9 a 66 ca n be use d i n c o nj u n ct i o n wi t h a n i n f r are d p hot oel ect ri c cham ber t o sen s e scattered lig h t fro m s m o k e p a rticles. sp ecial feat u r es are i n corporated in t h e desig n to facilitate cal i b rat i on and t e st i ng of t h e fi ni shed det ect or. 2.1 applied ar ea: phot oel ect ri c ty pe sm oke det ect or sy st em 2.2 featur es: 2.2.1 6 v t o 12 v operat i ng vol t a ge r a nge 2 . 2 . 2 in tern al tim e r & co n t ro l fo r red u ced sen s itiv ity 2.2.3 suppl y vol t a ge current 0~ 10ua 2.2.4 operat i ng tem p erat ure r a nge 25 75 2.2.5 power-on r e set 2. 2. 6 esd and lat c h-up prot ect i on c i rcui t r y on al l pi ns 2.2.7 piezoelectric horn driver 2. 2. 8 int e rconnect up t o 50 det ect ors 2.2.9 continuous modulated tone output for a lo cal or rem o te alarm condition 2.3 functional block diagram 2.4 pin description 2.5 pin function
pin no. pin symbol input/o utput function description 1 ,2 c1 , c2 exterior capacitor connected to the pins a capacitor connected to the pins determines the gain of the photo amplifier. 3 detect input input to the photo amplifier this pin connects the cathode of the photo diode. the photo diode is operated at zero bias. 4 strobe output regulated voltage output the pin is the regulated voltage output. the value is vdd-5v. 5 ,14 vdd , v ss power/gnd power supply 6 ired output signal output this pin is a output, which provides a pulsed base current for the external npn transistor, which drives the ir emitter. 7 i/o a connection at this pin allows multiple smoke detectors (less than 50) to be interconnected. 8 ,9 brass, silver output piezoelectric transducer output these two pins are used in conjunction with a piezoelectric transducer. 10 feedback inuput piezoelectric transducer input the pin is used in conjunction with a piezoelectric transducer feedback electrode. 11 led output signal output this open-drain nmos output is used to directly drive a visible led. the led also indicates detector status as follows (with component values as in the typical application, all times nominal) 12 osc input osc input the pin connects with exterior capacitor and resistor, sets the internal clock low time. 13 r1 exterior capacitor and resistor connected to the pins the pin connects with exterior capacitor and resistor, sets the internal ired output pulse period. 15 ls set intput low sensitive set this input pin serves two purposes in normal operation. this reference is established by a resistive divider between vdd and strobe. this allows the detector to have a different sensitivity set point during the timer mode. 16 test input test input this pin has an internal pull-down device and is used to manually invoke two test modes and a timer mode. 3. circuit characteristic: 3.1 the gain is determined by exterior capacitor c1 and c2. a capacitor connected to c2 determines the gain of the photo amplifier during standby. a typical value for this low-gain mode is 4700 pf but should be selected based on a specific photo chamber and the de sired level of sensitivity to smoke. av= ?
4.1 absolute maximum rating (voltages are referenced to vss) symbol parameter range unit standby 12
vic c o m m on m ode vol t a ge c1 c2 detect any al arm c ondi t i on v d d - 4 v d d - 2 v v r ef sm oke com p arator ref. volt. any al arm c ondi t i on v d d - 3 . 7 v d d - 3 . 3 v 5 typical application 6 calibration mode description fo r sen s itiv e d e tectin g an d calib ratin g sm o k e system , bl5 9 a 6 6 co u l d set calib ratio n mo d e . if test=v ss -1v , and drai ni ng 100ua current from t h e pi n. aft e r one peri od, b l 59a66 i s i n cal i b rat i on m ode if test pi n i s hi gh i m pedance condi t i on wi t h one peri od, b l 59a66 exi t cal i b rat i on m ode. the fol l o wi ng t a bl e i s shown t h e rel a t i v e descri pt i ons of cal i b rat i on m ode. pin sy m bol funct i on 7:i/o this pin is disabled as an output. a logic high on this pin places the photo am pl i f i e r out put on pi n 1 or pi n 2 as det e rm i n ed by pi n 15. the am pl i f i e r out put appears as pulses. 15: ls set if t h e i/ o pi n i s hi gh, t h i s pi n cont rol s t h e am pl i f i e r gai n capaci t o r. if pi n 15 i s l o w, norm a l gai n i s sel ect ed and t h e am pl i f i e r out put i s on pi n 1. if pi n 15 i s hi gh, supervi s ory gai n i s sel ect ed and t h e am pl i f i e r out put i s on pi n 2. 10: feedb a c k if pi n 7 i s hi gh and pi n 15 i s l o w (norm a l gai n ), t a ki ng t h i s pi n t o a hi gh l ogi c lev e l in creases th e am p lifier g a in b y ~1 0 % (h ysteresis). 12: osc thi s pi n m a y be dri v en by an ext e rnal cl ock source. 8: b r a ss thi s pi n i s reconfi gured as t h e sm oke i n t e grat or out put . three consecut i v e sm o k e d e tectio n s will cau se th is p i n to g o h i g h an d th ree co n s ecu tiv e n o sm o k e det ect i ons cause t h i s pi n t o go l o w. 1 1 : led thi s pi n becom e s a l o w-bat t e ry i ndi cat or. the open-drai n nm os out put i s norm a lly off. if vdd falls below the low battery threshold, the output turns on.
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