1/8 l9705 november 2003 n operating dc supply voltage range 5v to 25v n supply overvoltage pulse up to 40v n very low stand-by quiescent current, max 50 m a n internal clamping diodes at contact inputs to vs and gnd with pulse current capability up to +50ma, -75ma n chip enable function and tristate outputs for parallel bus connection n nominal contact currents of 10ma defined with external contact series resistors r in1-8 n contact status monitoring by means of comparing the resistance at contact sense inputs with the internal reference resistor value n resistance comparing with hysteresis for high noise immunity and immunity to ground and battery potential differences description the l9705 is a bipolar monolithic integrated circuit for monitoring the status of up to four contacts con- nected to gnd and up to four contacts connected to the battery. the contact sense input supply the contact current and perform the contact resistance comparison function. at the output the contact status is translated into a logical low level (contact closed) or logical high level (contact open). dip20 so20 ordering numbers: l9705 L9705D double quad contact interface circuit block diagram obsolete product(s) - obsolete product(s)
l9705 2/8 absolute maximum ratings pin connection (top view) thermal data symbol parameter value unit v sdc dc supply voltage +26 v v sp peak transient supply voltage (t 400ms) +40 v v cc logic supply voltage 7 v i indc input dc current 40 ma i inp input pulse (t p = 0 to 2ms; f 0.2hz; n = 25000) -75 to 50 ma i out output current (v o = 0 to 5.5v) internally limited v en enable input voltage v cc +0.3v;-0.3v v p tot total power dissipation (t amb = 80c) dip 20 so 20 875 420 mw mw t j junction temperature range max 150 c symbol parameter dip20 so20 unit r th j-amb thermal resistance junction to ambient 80 165 c/w obsolete product(s) - obsolete product(s)
3/8 l9705 notes: 1. the input resistor threshold value is a resistor value from the in-pin to ground at which the corresponding output chan ges its status (fig.4) 2. s i in is the sum of the in5 to in8 input currents. 3. the delay times are defined from the crossing point of 50% initiating signal amplitude to the crossing point of 50% output si gnal amplitude electrical characteristcs (v s = 5 to 25v, v cc = 4.75 to 5.25v, v bat -0.5v < v s ,< v bat -1v , t j = C40 to 150c unless otherwise specified.) symbol parameter test condition min. typ. max. unit v enl enable input voltage low (device activated) -0.3 0.8 v v enh enable input voltage high 2.4 v cc v v enh enable input threshold hysteresis 200 420 800 mv i en enable input current 2.4v < v en < v cc 0v < v en < 0.8v -5 -1 5 m a m a v outh output voltage high 0 < i out < 100 m a4v cc - 0.1 v cc v i out output current out status = high; v out = 0 0.5 2 ma v outl output voltage low i out = -1ma 0.05 0.2 0.4 v i out output current out status = low; v out = 5.5v -5 -20 ma i out ts output tristate current 0 < v out < v cc 0.5 m a v in 1,4 input voltage (device active) en = low; r in = 1k w v s - 2 v s - 1.5 v s - 0.4 v v in 5,8 input voltage (device active) en = low; r in = 1k w 0.4 1.5 2 v v in input voltageduring clamp (device disabled) en = high; i in = 30ma i in = -30ma v s +0.3 -2 v s +1 -1 v s +2 -0.3 v v r il 1,4 input resistor low threshold (note 1) 5v < v s <16v; ?d v gnd ? 0.1v s ?d v bat ? 0.1v bat 1.8 4 k w r il 5,8 input resistor low threshold (note 1) 5v < v s <16v; ?d v gnd ? 0.1v s ?d v bat ? 0.1v bat 1.8 4.8 k w r ih 1,4 input resistor high threshold (note 1) 5v < v s <16v; ?d v gnd ? 0.1v s ?d v bat ? 0.1v bat 5.3 20 k w r ih 5,8 input resistor high threshold (note 1) 5v < v s <16v; ?d v gnd ? 0.1v s ?d v bat ? 0.1v bat 6.5 29 k w r il input resistor threshold ratio (note 1) 5v < v s <16v; ?d v gnd ? 0.1v s ?d v bat ? 0.1v bat 0.65 0.75 0.85 r ih input resistor threshold ratio (note 1) 5v < v s <16v; ?d v gnd ? 0.1v s ?d v bat ? 0.1v bat 0.65 0.75 0.85 i qc quiescent current en = high (t enh >20 m s) v s = 5 to 16v; t j = -40 to 85c 20 40 m a i qs quiescent current all contact open 10 m a i qs quiescent current all contact closed 35 m a s i in (2) quiescent current ?d v bat ? 0.1v bat 25 m a i qc quiescent current en = low 5 ma i qs quiescent current en = low 8 ma t do delay time/output (en low to output data ready) (note 3) c out 50pf 15+ 3r in cin m s t dts delay time/tristate (en high to output tristate) (note 3) c out 50pf 10 m s t dio delay time input-output (note 3) en = low; c out 50pf 6 ms obsolete product(s) - obsolete product(s)
l9705 4/8 figure 1. typical application diagram for the l9705 circuit. the current flowing in the arrow direction is assumed positive. the external capacitors cin and cout represent the total wiring capacitance at the corresponding pins. functional description the l9705 circuit monitors the status of the contacts which are connected through the series external re- sistors r in to the contact sense input pins. the contacts equivalent circuit is supposed to be as shown in fig.2 for gnd connected contacts (in 1 to 4) and as shown in fig. 3 for v bat connected contacts (in 5 to 8). figure 2. the contact sense input connection with the contact equivalent circuit for gnd connected contacts. figure 3. the contact sense input connection with the contact equivalent circuit for v bat connected contacts. obsolete product(s) - obsolete product(s)
5/8 l9705 the l9705 circuit compares the input current with the current through the internal reference resistor. the device is designed to work with an external input series resistor of r in1-8 = 1k w . with this input resistor the contact current, when the contact is closed and the device activated (en =low) is: , for gnd contacts, (1) , fro v bat contacts, (2) for this calculation the limit value of the v s to v in and v in saturation voltage of 2v was considered so that the lowest limit value of i in is calculated in (1) and (2) figure 4. the output voltage as a function of the input resistance at the corresponding sense input. the function of the circuit can be demonstrated with the transfer characteristics, showing the output status as a function of the input resistor r i , shown in figure 4. the input resistor is a sum of the r in and the con- tact resistance r con or r coff , for the closed contact: r i = r in + r con , (3) and for the open contact: r i = r in + r coff , (4) the output goes high when the input resistance increases above 5.3k w (gnd contacts) or 6.5k w (v bat contacts) and goes low, when the input resistance decreases below 4k w (gnd contacts) or 4.8k w (v bat contacts); these values are typical values for the switching thresholds. the limit values of r i = 1.8k w (gnd contacts) and r i = 1.8k w (v bat contacts) for low and r i = 20k w (gnd contacts) and 29k w (v bat contacts) for high implies that a contact with r con = 100 w ( at i in = 10ma) will be recognized as on = low and a contact with r coff = 19k w (gnd contacts) or 28k w (v bat contact) will be recognized as off = high. these limits are valid within the supply voltage range 6v v s 16v, the ground potential difference of d v gnd = 0.1v s , the battery voltage potential difference of d v bat < 0.1v bat and the variation of the re- verse battery protection diode d1 voltage from 0.5v to 1v. the internal clamping diodes at the contact monitoring inputs together with the external contacts series resistors r in allows to withstand the transients at the contact connection.the contact series resistor r in limits the input current at the transient. the dynamic behaviour of the circuit is defined with the times t do and t dts . when the contact is open, the input capacitor c in must be charged through the resistor r in . in this case the total delay time tdo may be influenced also with the time constant r in c in . the delay time t dts , when disabling the device, is defined only with the internal circuitry. in both cases, output external capacitance less than 50pf is assumed, the internal output capacitance of the tristate buff- ers are less than 5pf. i in v s 2v C 1k w -------------------- - = i in v bat v bat 2v C d + 1k w ---------------------------------------------------- = obsolete product(s) - obsolete product(s)
l9705 6/8 dip20 dim. mm inch min. typ. max. min. typ. max. a1 0.254 0.010 b 1.39 1.65 0.055 0.065 b 0.45 0.018 b1 0.25 0.010 d 25.4 1.000 e 8.5 0.335 e 2.54 0.100 e3 22.86 0.900 f 7.1 0.280 i 3.93 0.155 l 3.3 0.130 z 1.34 0.053 outline and mechanical data obsolete product(s) - obsolete product(s)
7/8 l9705 outline and mechanical data dim. mm inch min. typ. max. min. typ. max. a 2.35 2.65 0.093 0.104 a1 0.10 0.30 0.004 0.012 b 0.33 0.51 0.013 0.200 c 0.23 0.32 0.009 0.013 d (1) 12.60 13.00 0.496 0.512 e 7.40 7.60 0.291 0.299 e 1.27 0.050 h 10.0 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 l 0.40 1.27 0.016 0.050 k 0? (min.), 8? (max.) ddd 0.10 0.004 (1) d dimension does not include mold flash, protusions or gate burrs. mold flash, protusions or gate burrs shall not exceed 0.15mm per side. so20 0016022 d obsolete product(s) - obsolete product(s)
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