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L9703-L9703D
OCTAL GROUND CONTACT MONITORING CIRCUIT
L9703OCTAL GROUND CONTACT MONITORING CIRCUIT.OPERATING DC SUPPLY VOLTAGE RANGE TO 25V.SUPPLY OVERVOLTAGEPULSE UP TO 40V.VERY LOW STANDBY QUIESCENT CUR-
RENT 0.2mA.INTERNAL CLAMPING DIODES AT CONTACT
INPUTS TOVS AND GND.INPUT PULSE CURRENT CAPABILITY UP TO 50mA;– 75mA.NOMINAL CONTACT CURRENT OF 10mADE-
FINED BY EXTERNAL CONTACT SERIES RE-
SISTORSRI N1–8.CONTACT STATUS MONITORING BY COM-
PARING THE RESISTANCE AT CONTACT
SENSEINPUTS WITHTHEINTERNALREFER-
ENCE RESISTOR VALUE.HIGHIMMUNITY DUE TORESISTANCE COM-
PARISON WITH HYSTERESIS
BLOCK DIAGRAM
SO-20L
DIP-20
ORDERINGNUMBERS: L9703 (DIP-20)
L9703D (SO-20L)
DESCRIPTIONThe L9703isa bipolarmonolithicintegratedcir-
cuitfor monitoring the statusofupto eight con-
tacts connectedto GND. containseight contact senseinputs and eight
microcomputer compatiblethree-state outputs.
PIN CONNECTION (top view)
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Test Conditions Unit Transient Supply Voltage(t≤ 1s) +40 V
VCC Logic Supply Voltage 7 V
IINDC Input DC Current ±40 mA
IINP Input DC Pulse
(test pulse specification:0
-75 Output Current Internally Limited
VEN Enable Input Voltage VCC +0.3
-0.3 Power Dissipationat Tamb =80°C
DIP20
SO20
Tstg,TJ Storage and Junction Temperature Range -55to 150 °C
THERMAL DATA
Symbol Parameter DIP20 SO20 Unit
Rth j-amb Thermal Resistance Junctionto Ambient MAX. 80 165 °C/W
L9703
ELECTRICAL CHARACTERISTICS (5V≤VS≤ 25V;-40°C ≤ Tj≤ 125°C; 4.75V≤ VCC≤ 5.25V unless oth-
erwise specified;the currents flowingin the arrowdirection are assumedpositiveas markedin theapplicationcircuit diagram,fig.1).
Symbol Parameter Test Conditions Min. Typ. Max. Unit
VENL Enable Input Voltage LOW
(device activated)
0.8 V
VENH Enable Input Voltage HIGH 2.4 V
VENhyst Enable Input Hysteresis 200 420 800 mV
IEN Enable Input Current 2.4V< VEN VOUTH Output Voltage HIGH 0< IOUT< 100μA 4.0 VCC -0.1 VCC V
VOUTL Output Voltage LOW IOUT= -1mA 0.05 0.2 0.4 V
IOUTTS Output TRISTATE Current 0< VOUT VIN Input Voltage (device active) EN= LOW
RIN =1kΩ VS-2 VS-1.5 VS-0.4 V
VIN Input Clamped Voltage
(device disabled)= HIGH
IIN= 30mA
IIN= -30mA +0.3 +1+2
IOUT Output Current OUT= HIGH
VOUT =0
2mA
IOUT Output Current OUT= LOW
VOUT= 5.5V
-20 mA
RIL Input Resistor (note1)
LOW Threshold1.8 4 KΩ
RIH Input Resistor (note1)
HIGH Threshold
5.3 20 KΩ
Input Resistor
Threshold Ratio (note1)
0.65 0.75 0.85
IQC Quiescent Current EN= HIGH (tENH≥ 80μs)-40°C≤Tj≤ 100°C
0.12 0.16 mA
IQS Quiescent Current All Inputs Open 0.04 mA
All Inputs Closed 0.24 mA
IQC
IQS
Quiescent Current EN= LOW 6
tdo Delay Time/Output
(EN LOWto output data ready)
COUT≤ 50pF 15
+3RINCIN
tdTS Delay Time/Tristate
(EN HIGHto output TRISTATE)
COUT≤ 50pF 10 μs
Note:1. The inputresistor threshold valueis theresistorvalue from theIN-pinto ground atwhichthe corresponding output changes
itsstatus (seefig.3).
RIL
RIH
L9703
Figure1: Typical Application Diagramfor the L9703Circuit. The current flowingin the arrow directionis
assumed positive. The external capacitorsCIN andCOUT represent the total wiring capacitance the corresponding pins.
APPLICATION CIRCUIT
L9703
FUNCTIONAL DESCRIPTION
The L9703circuitmonitorsthe statusof thecontacts
connectedto ground and throughthis series exter-
nalresistorsRIN tothe contactsense input pins.The
contacts equivalent circuitis supposedto be as
shownin fig.2.
The L9703 circuit compares the input current with
the current through the internal reference resistor.
The deviceisdesigned toworkwithanexternalinput
seriesresistorof RIN1-8=1kΩ. Withthis inputresistor
the contact current, when the contactis closed and
the device activated (EN= LOW)is -2VIIN= 1kΩ (1)
For this calculation the limit valueof theVStoIN
saturation voltageof2V was consideredso that the
lowest limit valueofIINis calculatedin (1).
The functionof the circuit canbe demonstratedwith
the transfer characteristics, showing the output
statusasa functionof the input resistor RI, shown figure3. The input resistorisa sumof the RIN and
the contactresistanceRCON orRCOFF, forthe closed
contact: =RIN +RCON, (2)
andfor the open contact: =RIN +RCOFF. (3)
The outputgoesHIGH when the input resistancein-
creasesabove5.3kΩ (typical value) andgoesLOW,
when the input resistance decreases below 4kΩ
(typical value). The limit valuesofRI= 1.8KΩ for
LOW andRI =20kΩfor HIGH implies thata contact
withRCON =100Ω (atIIN= 10mA) willbe recognized ON= LOW anda contact with RCOFF =19kΩ will recognizedas OFF= HIGH. These limits are
valid within the supply voltage range6V≤ VS≤ 16V
and the ground potential difference of
ΔVGND = 0,1V.
The internal clamping diodesat the contact moni-
toring inputs, togetherwith theexternalcontacts se-
ries resistors RIN, allows the deviceto withstand
transientsat thecontactconnection.The contactse-
ries resistor RIN limits the input currentat the tran-
sient.
The dynamic behaviourof the circuitis definedby
the timestdo and tdTs. When the contactis open,the
inputcapacitor CIN mustbe charged throughthere-
sistor RIN.In this case the total delay time may also influencedby the time constant RINCIN.
The delay time tdTs, whendisablingthe device,isde-
fined only bythe internal circuitry.In both cases,an
external output capacitance less than 50pFis as-
sumed, the internal output capacitancesof the
three-statebuffers are less than 5pF.
Figure2: The Contact SenseInput Connectionwith the Contact Equivalent Circuit.
L9703
Figure3: The Output Voltageasa Functionof the Input Resistanceat the Corresponding Contact Sense
Input.
L9703
