A4231 general features the A4231 is a proximity sensor integrated circuit to be used with a broad range of inductive single-coiled proximity transducers in proximity detection applications ? monolithic ic in bipolar technology ? user-adjustable sensing range by means of a single external resistor ? user-adjustable hysteresis (015%) ? 5.5v35v broad supply voltage range ? low-voltage operation possible using stabilised 4.5v5.5v voltage source ? internal voltage regulator to improve immunity against fluctuations of supply voltage ? broad operating temperature range: -25c...90c ? can work with a broad selection of inductive transducers ? npn open collector output with guaranteed sink current of 150ma ? output overload/over current protection ? integrated power-on and detect led drivers ? normally open(no)/normally closed(nc) select pin ? broad range of operating frequencies: 100khz1mhz ? output over current and short-circuit protection ? easy temperature compensation of proximity transducers ? package C qfn-24 example application schematic l 1 A4231 l 2 l inductive transducer vcc no/nc no/nc outn outn c res gnd vcc r f cdet, 10% (optional) c det d_led 220nf/6.3v 20% rhyst, 5% (optional) min. 2.2uf/40v electrolytic 220nf/6.3v 20% ceramic 91kohm p_led covl, 10% 100nf/6.3v c ovl r h r f c f 100nf/6.3v 10% rref r s,n 1r6 5% 125mw rsn c b gnd1 typical application schematic of a proximity sensor/detector
electrical characteristics dc characteristics the typical values are given for v cc =24v and t j = 25c unless otherwise specified. # symbol parameter conditions min typ max unit 1 i vcc,off supply current output inactive (off) 3.8 4.8 ma 2 i vcc,on supply current output active (on) 8.5 12 ma 3 v sat,out output saturation voltage i out =150ma 0.50 0.70 v 4 i led led current 1.0 1.2 1.6 ma 5 i lkg output leakage current <1 20 a 6 i th,ovl overload threshold current* 1) 158 190 220 ma * 1) Coverload threshold current is the level of the output current which triggers the overload protection circuit. ac and timing characteristics the typical values are given for v cc =24v and tj = 25c unless otherwise specified. # symbol parameter conditions min typ max unit 1 f osc operating frequency defined by external lc tank 0.1 1.0 mhz 2 r n negative resistance between pin l1 and ground r n = C2r f +/-3% -200 -2 k 3 f max maximum switching frequency* 1) c det =4.7pf, f osc =600khz c det =33pf f osc =100khz 5 2 khz 4 h w hysteresis width depends on r hyst 0 15 % 5 t r output rise time load=1kohm <1.5 s 6 t f output fall time* 2) load=1kohm <1 s 7 t s,ovl sampling period in overload mode depends on c ovl 50 120 250 ms 8 t startup startup time* 3) 50 120 250 ms 10 c in input capacitance measured between pin l1 and ac ground (pin l2) for f osc =0.21mhz and |r n | =2100kohm 6 8.5 13 pf * 1) C these are maximum switching frequencies of the ic itself; switching frequencies of sensors may be higher than those given above, * 2) C the fall time on leaving the start-up interval depends on the load used and can be as long as 10ms, * 3) C this is the maximum start-up time of the chip itself; this parameter does not reflect performance of a sensor; during the start-up interval the output is inactive (off) regardless of the state of the no/nc pin.
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