Nju7870, an excitation amplifier developed by Nippon wireless and tamakawa Seiki for vehicle mounted resolver, has begun to provide samples

Nju7870, a new low-voltage drive resolver (angle sensor) excitation amplifier developed by Nippon wireless for detecting the rotation angle of drive shaft and rotary shaft of hybrid electric vehicle and electric vehicle, has begun to provide samples. The amplifier can simplify the design of excitation circuit, realize the miniaturization and lightweight of actual circuit board and ECU ⁃ 1, and improve product reliability.

1 ECU: electronic control unit


High precision angle detection and high safety are required for the driving motor of environment-friendly vehicles such as hybrid electric vehicles and electric vehicles, so the resolver (angle sensor) used to detect the angle of driving shaft and rotating shaft plays an important role. In the resolver system, the R / D converter which converts the detected resolver signal into digital signal and the excitation circuit which provides excitation signal to the resolver are needed.

Tamakawa Seiji, which has high market share and market performance in resolver and R / D converter products, cooperates with Nippon wireless to develop high-performance resolver system, so this resolver excitation amplifier nju7870 product is developed.

[product features]

1. The most suitable voltage input and current output excitation circuit for resolver greatly reduces the design burden

In the past, when constructing the excitation circuit of voltage input and current output (current control mode), the resolver is an inductive load, which increases the complexity of the circuit design. There are often some problems, such as the simple calculation and the actual measurement. It takes a lot of design effort to get the desired features. Nju7870 integrates the excitation circuit of differential voltage input and differential current output, which can realize the circuit characteristics most suitable for driving resolver. It only needs to input the differential voltage signal of the desired current. It is a good product that is very easy to use. It solves the problem of the previous discrete component circuit design and greatly reduces the design time.

Nju7870 excitation circuit (composed of differential voltage input and differential current output)

2. Two excitation circuits are used, which can be used in many kinds of resolver systems

Nju7870 is equipped with two differential voltage input and differential current output circuits. It can be used in combination with various resolvers to control each circuit to form 1-Phase excitation or 2-phase excitation mode. In addition, it realizes the high-precision characteristic matching of each phase which is difficult to achieve in the discrete structure, especially the two-phase excitation resolver system, which is conducive to the high performance of motor rotation angle detection.

Example of circuit composition

3. Small package SSOP16 is adopted to realize miniaturization of circuit board with minimum external components

Nju7870 adopts small package SSOP16, external components only need to connect the capacitor of power terminal. Compared with the previous discrete circuit structure, the actual installation area is greatly reduced

(90% reduction in the composition of discrete circuits compared with the past: survey results of the company).

[product performance]

Working voltage (2.4V to 5.5V)

Differential voltage input and differential current output

● transconductance (13.5map / vpptyp)

Working temperature range (TOPR = – 40 ° CTO + 125 ° C)

Consumption current (4matyp.)

Built in overheat shutdown circuit

Built in external control shutdown function

Package (SSOP16)


Angle sensor (resolver excitation circuit)

Product appearance


[sample / production plan]

Samples have been provided

The mass production plan starts in April 2021

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