New Japan Radio (NJR) has developed a high voltage monitor IC "NJU7890" that can detect DC 1000 V voltage and output with high precision, and announced that mass production has begun.
Small size and high performance have been required for inverters and batteries in eco-friendly cars such as hybrid cars and electric cars. Among them, the voltage monitor module has been composed of multiple detection resistors and operational amplifiers discretely, so there have been some problems, for example, the area of high voltage circuits has increased in ECU and the discrete configuration has caused the deterioration of the attenuation rate precision. NJR has developed a new IC NJU7890 with high input resistance as a one-package solution and high precision, and it has entered the mass production.
The voltage monitor block with NJU7890 improves the performance of eco-friendly cars and makes them smaller and lighter.
Conventional high voltage monitor circuits have required multiple detection resistors, operational amplifiers, etc. to construct high input resistance with discrete parts. In order to ensure multiple parts and creepage distance, there have been some problems with external parts, for example, the mounting area has increased in the ECU and the error of each part has caused the deterioration of the attenuation rate precision.
The NJU7890 realizes high precision of resistance matching by integrating a high input resistance of 30 MΩ and a high precision amplifier in one-package.
It is possible to apply a voltage up to 1000 V directly to the NJU7890, and attenuation rate precision is reduced to 1/10 of the conventional value in the operating temperature Ta = –40 to +125 °C range, and the attenuation rate can reach ±1%.
Therefore, it can realize high precision voltage monitoring and contribute to more efficient electrical energy control.
The NJU7890 uses a small size package PMAP11 that ensures the 1000 V voltage creepage distance. PMAP11 is a leadless package with mounting strength of 2000 cycles or more by expanding the 4 corner terminals. The wettable flank configuration enables visual inspection of solder joints during the installation of the ECU. Since all the feedback resistors are built-in, the external parts are no longer required.
The NJU7890 uses the package PMAP11 which can provide safety and security and ensure the reliability and can meet the small size and weight reduction for automotive ECUs. So it contributes to significant reduction of the mounting area compared with the conventional discrete circuit configuration.
- Common mode input voltage +1000 V
- Differential input voltage ±1000 V
- High precision attenuation rate ±1%,(Ta = –40 to +125 °C)
- High input resistance 30 MΩ min
- Operating voltage range 2.2 V to 5.5 V
- Operating temperature range Ta = –40 to +125 °C
- Package PMAP11
- Power Control Unit (PCU)
- Inverter Control