Other Parts Discussed in Thread: LM5176, CSD19502Q5B
Dear Support, my design has this spec. : Vin=10-32V, Vout=24V, Iout=20A (based on LM5175 or LM5176). My target is to reduce LM517x power loss so I prefer to use Optional input to the VCC bias regulator (powering VCC from an external regulator). In LM5175 datasheet, Ivcc is 65mA minimum. In old E2E forum post (“LM5176: LM5176, how much bias current of internal regulator can handle?”) I read “…the current limit for BIAS is the same for the VCC regulator. Hence, your design should also observe 65mA as the guaranteed current…”
VCC regulator supplies the drivers; NMOS DRIVERS have current capability to “Driver peak source current” 1,8 ampere. I use 8 FETs (CSD19502Q5B, Qg Gate Charge Total, typ 48nC max 62nC) in output H-Bridge. Fsw=500KHz. So Driver Consumption can be estimated as 4 x Qg x Fsw that is about 125mA (max).
So I consider 65mA+125mA = 190mA (with 4 FETs powered out of 8) to dimension external regulator. This means design external regulator with this spec. : Vin=24V, Vout=10V, Iout=190mA.
I forgot other consumptions? In my design, which is maximum current that can be drawn from external regulator for power BIAS pin (IVcc)?
