Part Number: CSD97396Q4M
I'm using the CSD97396 to implement a buck-boost circuit. The PWM and skip is connected to a FPGA. They are 3.3V signal. The PWM frequency is 400KHz. No matter I change the signal, there is no voltage output. I cannot get any voltage on SW pin of U17 even I set pwm = 1. The Vin is 12V in my test. R169 and R170 change to 1ohm.
Could you help to check what is the problem?
Product Marketing Engineer, Mid-Voltage FET
In reply to Brett Barr1:
Hi Brett Barr,
I used the multimeter measure the voltage on C147 and R169. The voltage of BOOT pin is 4.9V, the voltage of BOOTR pin is close to 0.
Is there any problem?
In reply to HongRen Chang:
Thanks a lot.
It works when I set skip low first and then go to high.
But I found a strange thing.
1. When I set the circuit worked under buck mode. skip1=1,and pwm1 = pwm_sig. skip2=1 and pwm2 = 1. The buck side works well. I meaused the voltage on the inductor, it changes as expected. The U18 should worked under pass through mode as I expected, but the voltage of Vin on U18 is the double voltage of the inductor .
2. When I set the circuit worked under boost mode. skip = 1 and pwm1= 1, skip2 = 1 and pwm2 = pwm_sig. The high side mosfet of U17 seems not opened fully. The input voltage 12V, the voltage on inductor is only 0.4V. the U18 seems worked, the output signal is changed with different pwm frequency.
It seems the device worked strangely when PWM is always 1. What is the problem?
By the way, Is there any limit for the output for chip? 0~24V?
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