Features: ·Adaptive hysteresis
·Single supply operation
· Ground referenced input
·True zero crossing timing reference
·Operates from 2V to 12V supply voltage
·Handles inputs from 100 mV to over 120V with external resistor
·CMOS compatible logicApplication·Position sensing with notched wheels
·Zero crossing switch
· Motor speed control
· Tachometer
·Engine testingPinout
Specifications
| Temperature Min |
-40 deg C |
| Temperature Max |
125 deg C |
| Function |
VRS |
| View Using Catalog |
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.
Supply Voltage ......................................................12V
Power Dissipation (Note 1) ..........................1250 mW
Operating Temperature Range............-40 to +125
Storage Temperature Range ..............-65 to +150
Junction Temperature (Note 2) ........................+125
Input Current .................................................±30 mA
Lead Temperature (Soldering, 10 sec.) ..............260
DescriptionThe LM1815 is an adaptive sense amplifier and default gating circuit for motor control applications. The sense amplifier provides a one-shot pulse output whose leading edge coincides with the negative-going zero crossing of a ground referenced input signal such as from a variable reluctance magnetic pick-up coil.
In normal operation, this timing reference signal is processed (delayed) externally and returned to the LM1815. A Logic input is then able to select either the timing reference or the processed signal for transmission to the output driver stage.
The adaptive sense amplifier operates with a positive-going threshold which is derived by peak detecting the incoming signal and dividing this down. Thus the input hysteresis varies with input signal amplitude. This enables the circuit to sense in situations where the high speed noise is greater than the low speed signal amplitude. Minimum input signal is 150mVP-P.
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
| LM1815M |
SLM |
0 |
42786 |
0 |
0 |
3352500 |
2 |
951281028 |
| LM1815MX |
SLM |
0 |
42786 |
0 |
0 |
3352500 |
2 |
951281028 |
| LM1815N |
SLM |
0 |
42786 |
0 |
0 |
3352500 |
2 |
951281028 |
Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.For more information on Reliability Metrics, please click here.
The LM1815 is an adaptive sense amplifier and default gating circuit for motor control applications. The sense amplifier provides a one-shot pulse output whose leading edge coincides with the negative-going zero crossing of a ground referenced input signal such as from a variable reluctance magnetic pick-up coil.
In normal operation, this timing reference signal is processed (delayed) externally and returned to the LM1815. A logic input is then able to select either the timing reference or the processed signal for transmission to the output driver stage. The adaptive sense amplifier operates with a positive-going threshold which is derived by peak detecting the incoming signal and dividing this down. Thus the input hysteresis varies with input signal amplitude. This enables the circuit to sense in situations where the high speed noise is greater than the low speed signal amplitude. Minimum input signal is 100 mVp-p.
LM1815 Data Sheet
