LM903N

LM903 NSC | Alldatasheet

Document overview

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Technical content

Features

Y Flashing or continuous warning indication Y Warning threshold externally adjustable Y Control circuitry for thermal-resistive probe Y Switch on reset and delay to avoid transients Y 600 mA flashing lamp drive capability Y Short and open circuit probe detection Y 70V transient protection on supply and control input Y 7V–18V supply range Y Internally regulated supply Y b40§Ct o a80§C operation Connection Diagram Dual-In-Line Package TL/H/5699–1 Order Number LM903N See NS Package Number N16E C1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage, V CC 18V Control Input Voltage (Pin 7) 18V Transient Voltage (Pins, 6, 7, 9) 10 ms (Note 1) 70V Output Current (Pin 4) I 4 (Sink) 10 mA Operating Temperature Range b40§Ct o a85§C Storage Temperature b55§Ct o a150§C Maximum Junction Temperature a150§C Lead Temperature (Soldering, 10 sec.) 260 §C

Electrical Characteristics

VCC e 12V, C T e 33 mF, R T e 7.5 k X,T A within operating range except where stated otherwise Tested Limits Design Limits Symbol Parameter Conditions (Note 2) (Note 3) Units Min Max Min Typ Max VCC Supply Voltage 7.0 18 7.0 13 18 V IS Supply Current 50 50 mA Regulation V CC e 7.2V–18V 105 mV Temperature Drift 500 mV/§C VREF Measurement Reference Voltage 790 900 780 850 910 mV RREF Reference Input Resistor 1.2 k X V7 Start Input Logic High Level 1.6 V V7 Start Input Logic Low Level 1.0 V I7 High Input Current Latch Off 100 nA I7 Latch Holding Current Latch On 2.5 nA R7 Resistance Pin 7 Latch On 22 k X I12 Ramp Current See Timing Diagram Charging V 12 e 0V–1V 600 1100 590 1100 mA V12 e 1V–4V 53 93 50 96 mA Discharging V 12 e 4.1V b700 b450 b710 b440 mA V12 e 0.5V b650 b400 b660 b390 mA V12 Ramp Threshold See Timing Diagram Probe Current Start 570 850 550 710 870 mV First Measurement 910 1200 890 1055 1220 mV Second Measurement 910 1240 890 1080 1270 mV V1 Probe Input Voltage Range V CC e 7.5V–18V 1 V REGb1.0 V V5 Probe Open-Circuit Threshold At Pin 5 V REGb0.85 V REGb0.6 V V5 Probe Short-Circuit Threshold 0.6 0.85 V I1 Pin 1 Input Leakage Current Pin 1 e 300 mV b3.5 a3.5 a5.0 nA I15 Pin 15 Leakage Current V 15 e 2V, V 7 e 12V b3.5 3.5 mA Pin 15 Charging Current V 15 e 4V, V 7 e 12V 60 mA f9 Lamp Oscillation Frequency C L e 3.3 mF 0.5 1.5 2.5 Hz I9 Lamp Driver Current Flashing Mode 600 mA V9 Lamp Driver Saturation I 9 e 200 mA 200 250 mA

Electrical Characteristics (Continued) VCC e 12V, C T e 33 mF, R T e 7.5 k X,T A within operating range except where stated otherwise Tested Limits Design Limits Symbol Parameter Conditions (Note 2) (Note 3) Units Min Max Min Typ Max V14 Auxiliary Output Lamp OFF 5.0 V Voltage Lamp ON 1.2 V V1 Alarm Level (Difference Between First 230 280 330 mVand Second Measurement) Sensitivity to Electrostatic Discharge: Pins 7, 10, 13, and 14 will withstand greater than 1500V when tested using 100 pF and 1500 X in accordance with National Semiconductor standard ESD test procedures. All other pins will withstand in excess of 2 kV. Note 1: Test circuit for overvoltage capability at pins 3, 6, 7. Note 2: Guaranteed 100% production tested at 25 §C. These limits are used to calculate outgoing quality levels. Note 3: Limits guaranteed to include parametric variations. T A eb 40§Ct o a80§C and from V CC e 7.5V–18V. These limits are not used to calculate AOQL figures. Note 4: Variations over temperature range are not production tested. TL/H/5699–2 In Lamp ON condition, I 9 should be limited to 600 mA. Block and Application Circuit TL/H/5699–3 Memory capacitor on pin 15 is set HighÐLamp off LowÐLamp on

Equivalent Schematic Diagram TL/H/5699–6

INTERNAL COMBUSTION ENGINE OIL LEVEL The basic system provides a single shot measurement when the supply is applied and has a primary application in automotive oil, hydraulic fluid and coolant monitoring. Partic- ularly in the case of the oil level, a valid measurement is only possible before the oil is disturbed. The application cir- cuit shown is arranged such that the measurement is made when the ignition is switched on via switch A. Switch B is the oil pressure sensor and is closed before the engine starts, keeping pin 7 low and enabling the measurement. STALLING AND RESTART PROTECTION The 4M7 resistor and 10 mF capacitor connected to pin 7 provide the restart protection. When oil pressure builds up, switch B opens and the 10 mF capacitor charges through the bulb. At switch-off, the capacitor discharges slowly and is capable of preventing a low state on pin 7 for 1 minute. Unless pin 7 is low, a new measurement can not be made and the previous measurement result stored in the memory capacitor on pin 15 is used to control the output. MEMORY The pin 15 memory output goes high if a correct measure- ment is made (lamp off). If the power is removed, pin 15 leakage is less than 3 mA and the memory status is retained for some time. Provided pin 15 voltage does not fall below 3V, the memory capacitor will be refreshed on powering up again. There is no internal pull down on detecting an incor- rect measurement. If it is required to use pin 15 as an output indicating the measurement result, an external pull down resistor and buffer will be required. CONTINUOUS WARNING LAMP The lamp can be arranged to light continuously by disabling the oscillator with a resistor of 150k or less, connected be- tween pins 10 and 11. REPETITIVE MEASUREMENTS Measurements may be repeated by strobing the supply to pin 6. The probe current regulator transistor must have the same supply as pin 6, but the warning lamp can be perma- nently powered. The lamp will light during each measure- ment and will flash in between measurements when incor- rect conditions are detected. ALTERNATIVE APPLICATIONS Gas flow detection: The cooling effect of gas flowing over a probe could be used to provide a warning signal from the LM903 in the event of gas failure. Automatic top up: With the LM903 strobed continuously, the output may be stored, buffered, and used to drive sole- noid valves to correct a fluid level as required.

LM903 Fluid Level Detector Physical Dimensions inches (millimeters) Molded Dual-in-Line Package (N) Order Number LM903N LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or 2. A critical component is any component of a life systems which, (a) are intended for surgical implant support device or system whose failure to perform can into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life failure to perform, when properly used in accordance support device or system, or to affect its safety or with instructions for use provided in the labeling, can effectiveness. be reasonably expected to result in a significant injury to the user. National Semiconductor National Semiconductor National Semiconductor National Semiconductor Corporation Europe Hong Kong Ltd. Japan Ltd.

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