TI中文支持网Part Number:LMP8481-Q1Other Parts Discussed in Thread: LMP8481
我在做一款三相直流无刷电机(BLDC)的电机驱动电路，电机功率是28V/100W，我需要三颗同型号的相电流(双向)检测芯片，目前使用了贵司的LMP8481ATQDGKRQ1：
主要参数如下：
I am making a motor drive circuit for a three-phase brushless DC motor (BLDC), the motor power is 28V/100W, I need three phase current (bidirectional) detection chips of the same model, currently I use your company's LMP8481ATQDGKRQ1:
The main parameters are as follows:
GAIN=20
VCC=5V，VCC via C=0.1uF and 4.7uF to GND
REFA short REFB=2.5V：via 0.1uF to GND
Rsense=5mΩ
Rsense_left via R=0Ω to RSP
Rsense_right via R=0Ω to RSN
RSP via C=0.1uF to RSN
Vout via RC(R=100Ω，C=4.7nF) to MCU GPIO
But I ran into a problem, as shown below: Vout of LM8481-Q1 is wrong !
CH4（green）：current from UA to Motor
CH2（yellow）：Vout of LMP8481-Q1
CH3（red）:UA, phase Voltage
Please help analyze it, thank you!
兔撵狗子：
“”Vout via RC(R=100Ω，C=4.7nF) to MCU GPIO“”，给电路引入了附加相移，降低了相位裕度。导致电压过冲甚至自激震荡，CH2（yellow）清晰体现此现象。
应使电容C<500pF甚至更低，可以解决该问题。必要情况考虑使用有源滤波器。
,
?? ?：
I use electronic load to replace Motor，phase Voltage UA via a electronic load to UB，but LMP8481 Vout unable to display negative current。
Iout=2A，RSP to RSN is 10mV，Vout=2.5V+2A*5mΩ*20=2.5V+0.2V=2.7V，it’s true！
Iout=-2A，RSP to RSN is -10mV，Vout=2.5V. it‘s wrong，why Vout≮ 2.5V？
