Overview
The LM2917N-8/NOPB, produced by Texas Instruments, is a monolithic frequency-to-voltage converter designed for a wide range of applications. This device integrates a high-gain operational amplifier and a tachometer circuit, making it versatile for various frequency measurement and control tasks. The LM2917N-8/NOPB is particularly useful in systems requiring accurate frequency-to-voltage conversion, such as speed sensing, tachometers, and control systems.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage | 0 to 28 | V |
| Collector Voltage | 0 to 28 | V |
| Input Voltage Range (Tachometer) | ±28 | V |
| Power Dissipation (8-pin) | 1200 | mW |
| Operating Temperature Range | -40 to 85 | °C |
| Storage Temperature Range | -65 to 150 | °C |
| Input Thresholds (VIN = 250 mVp-p at 1 kHz) | ±10 to ±40 | mV |
| Hysteresis (VIN = 250 mVp-p at 1 kHz) | 30 | mV |
| Input Bias Current (VIN = ±50 mVDC) | 0.1 to 1 | μA |
| Linearity (Typical) | ±0.3% |
Key Features
- Ground-referenced tachometer input interfaces directly with variable reluctance magnetic pickups.
- Op amp with floating transistor output capable of sinking or sourcing up to 50 mA to operate relays, solenoids, meters, or LEDs.
- Frequency doubling for low ripple.
- Built-in hysteresis with either differential input or ground-referenced input.
- Output swings to ground for zero frequency input.
- Easy to use with the formula VOUT = fIN × VCC × R1 × C1.
- Zener regulator on chip for accurate and stable frequency-to-voltage or current conversion.
- Differential input options allow for setting custom input switching levels.
Applications
- Over- and under-speed sensing.
- Frequency-to-voltage conversion (tachometer).
- Speedometers.
- Breaker point dwell meters.
- Hand-held tachometers.
- Speed governors.
- Cruise control.
- Automotive door lock control.
- Clutch control.
- Horn control.
- Touch or sound switches.
Q & A
- What is the primary function of the LM2917N-8/NOPB? The primary function is to convert input frequency to a corresponding voltage output.
- What types of inputs does the LM2917N-8/NOPB support? It supports both differential and ground-referenced inputs.
- What is the maximum supply voltage for the LM2917N-8/NOPB? The maximum supply voltage is 28 V.
- What is the operating temperature range of the LM2917N-8/NOPB? The operating temperature range is -40°C to 85°C.
- How much current can the op amp output stage handle? The op amp output stage can sink or source up to 50 mA.
- What is the typical linearity of the frequency-to-voltage conversion? The typical linearity is ±0.3%.
- What is the purpose of the built-in Zener regulator? The built-in Zener regulator allows for accurate and stable frequency-to-voltage or current conversion.
- Can the LM2917N-8/NOPB be used in automotive applications? Yes, it can be used in various automotive applications such as speed sensing and cruise control.
- How does the device protect against input voltage swings? The device is fully protected against voltage swings above VCC and below ground.
- What is the formula for calculating the output voltage? The output voltage can be calculated using the formula VOUT = fIN × VCC × R1 × C1.
