NJW4302 查看數據表（PDF） - Japan Radio Corporation

零件编号

产品描述 (功能)

生产厂家

NJW4302

THREE-PHASE DC BRUSHLESS MOTOR CONTROL IC

Japan Radio Corporation  

NJW4302

Preliminary

• FG Input

Internal FG Amplifier is a differential amplifier and both inputs and output are connected to the pin. The DC gain

of this amplifier, AFG, is:

AFG

=

R7

R8

C8 is for compensation or noise reduction, C9 is for DC cut. Typical value of C10 is 0.1 microfarad. The

inductor symbol connected FGIN is FG sensing copper pattern on PC board.

• PWM Frequency

PWM clock generates by CR oscillator. The frequency is:

f PWM

=

1

0.48 ⋅ R1⋅ C1

In fig.x*, fPWM is about 19kHz. If fPWM is about 20kHz, it could reduce audible noise.

• Variable range of VCO frequency

VCO frequency in typical value is recommend 160kHz to 1MHz. External constants is:

R2 = 20k ohm, C3 = 100pF, R3 = 27k ohm, C4 = 0.47 uF

If it can not be settled into this range, change the division of speed discriminator.

• Detecting time of rock protection

Detecting time is settled by C2 as follow:

tROCK = 66 ⋅ C2

In fig.x*, trock is about 3.1 sec.

• Integration Amplifier

Both speed discriminator output and PLL output should be mixed via two resistors before input to INTIN of

Integration Amplifier. Mixing resistor, Timing resistors and capacitors are necessary for good system operation.

C6 is need for non-polar type capacitor for good stability.

• Upper power transistor

To reduce ripple of power line, Upper output transistor is connect NJM4302 via common-base NPN transistors.

Minimum output current is 12mA, it is able to drive 1A class transistor. If more current is needed, change the

output transistor to Darlington type. Re-circulating diodes is needed on between collector and emitter of output

transistor.

• Lower power transistor

Lower output could drive external power transistor directly to about 1.5A. If more current is needed, change

the output transistor to Darlington type. The resistor connected between base and emitter of power transistor is

necessary on PWM operation for sharp cut-off of power transistor. When your system have any noise, attach a

capacitor in parallel the resistor.

Re-circulating diodes is needed on between collector and emitter of output transistor. R11 is a current sensing

resistor and settled by following:

R11 = VRE

IO

When VRF is sensing voltage, Io is sensing current. Take care of power dissipation of R11, also.

- 17 -

Share Link: