Overview
The LM2907MX/NOPB, produced by Texas Instruments, is a monolithic frequency-to-voltage converter integrated circuit. This device is designed to operate a relay, lamp, or other load when the input frequency reaches or exceeds a selected rate. It features a high-gain operational amplifier (op amp) and a tachometer circuit that uses a charge pump technique for frequency-to-voltage conversion. The LM2907 is available in various packages, including 8-pin and 14-pin configurations, making it versatile for different application needs.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Operating Temperature Range | -40 to 85 | °C |
| Supply Voltage | 0 to 28 | V |
| Output Sink Current | 50 | mA |
| Input Threshold Voltage | ±10 to ±40 | mV |
| Hysteresis | 30 | mV |
| Linearity | ±0.3% (Typical) | % |
| Package Types | PDIP (8, 14), SOIC (8, 14) | - |
| Junction-to-Ambient Thermal Resistance (RθJA) | 77.6 to 110 | °C/W |
Key Features
- Ground-referenced tachometer input interfaces directly with variable reluctance magnetic pickups.
- Op amp has a floating transistor output, allowing for either ground or supply-referenced loads up to 50 mA.
- Frequency doubling for low ripple.
- Tachometer has built-in hysteresis with either differential input or ground-referenced input.
- ±0.3% linearity (typical).
- Ground-referenced tachometer is fully protected from damage due to voltage swings above VCC and below ground.
- Output swings to ground for zero frequency input.
- Easy to use with the formula VOUT = fIN × VCC × R1 × C1.
- Zener regulator on chip allows accurate and stable frequency-to-voltage or current conversion (LM2917).
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 LM2907MX/NOPB?
The primary function of the LM2907MX/NOPB is to convert input frequency to a corresponding voltage or current, making it suitable for applications such as tachometers, speedometers, and over/under-speed sensing.
- What types of packages are available for the LM2907?
The LM2907 is available in PDIP (8, 14) and SOIC (8, 14) packages.
- What is the maximum output sink current of the LM2907?
The maximum output sink current of the LM2907 is 50 mA.
- How does the LM2907 protect against voltage swings?
The LM2907 is fully protected against voltage swings above VCC and below ground, ensuring robust operation in various environments.
- What is the linearity of the LM2907's frequency-to-voltage conversion?
The linearity of the LM2907's frequency-to-voltage conversion is typically ±0.3%.
- Can the LM2907 handle differential input signals?
- What is the purpose of the Zener regulator on the LM2917?
The Zener regulator on the LM2917 allows for accurate and stable frequency-to-voltage or current conversion.
- How does the frequency doubling feature work in the LM2907?
The frequency doubling feature in the LM2907 reduces output ripple by effectively doubling the input frequency, resulting in a smoother output voltage.
- What is the operating temperature range of the LM2907?
The operating temperature range of the LM2907 is -40°C to 85°C.
- Can the LM2907 be used in automotive applications?
