Other Parts Discussed in Thread: , CSD19531Q5A, CSD19533Q5A
Hello guys,
One of my customers is evaluating LM5145 using LM5145EVM-HD-20A (http://www.tij.co.jp/jp/lit/ug/snvu545a/snvu545a.pdf) for their new products.
But they can't buy Infineon device dut to their distribution channel. So they replace BSC117N08NS5 for Q1 and BSC037N08NS5 for Q2 on EVM
with TI, CSD19531Q5A for Q1 and CSD19533Q5A for Q2. Also they change the following spec of EVM too.
1. EVM output voltage: 5V -> 12.5V.
2. Output capacitor: 47uF*7 -> 47uF*1.
3. Inductance, L2 , 3.3uF -> 15uF.
4. Switching frequency: 220kHz -> 370kHz
5. Input voltage: 24V
When they measured effeciency of the EVM, the effeciency is about 90%. They thought it is low effeciency. So they cheched the gate voltage of Q1 and Q2.
As the result, they found Q1, the gate voltage of CSD19531Q5A(High side FET) was ringing dutring about 100ns with 5V swing .
They think the high side NMOSFET, CSD19531Q5A could not be used with LM5145 because of high speed turn on/off characterstics.
They wants know whether it is not good to use CSD19531Q5A for high side NMOSFET with LM5145 or not.
Could you please give us any comment? And if you have any idea, could you please tell us any TI NMOSFET part number for the high side NMOSFET?
Your reply would be appreciated.
Best regards,
Kazuya Nakai.
