FDMF6833C View Datasheet(PDF) - ON Semiconductor
Part Name
Description
MFG CO.
'FDMF6833C' PDF : 21 Pages View PDF
Application Information
Supply Capacitor Selection
For the supply inputs (VCIN), a local ceramic bypass
capacitor is recommended to reduce noise and to
supply the peak current. Use at least a 1 µF X7R or X5R
capacitor. Keep this capacitor close to the VCIN pin and
connect it to the GND plane with vias.
Bootstrap Circuit
The bootstrap circuit uses a charge storage capacitor
(CBOOT), as shown in Figure 32. A bootstrap capacitance
of 100 nF X7R or X5R capacitor is usually adequate. A
series bootstrap resistor may be needed for specific
applications to improve switching noise immunity. The
boot resistor may be required when operating above
15 VIN and is effective at controlling the high-side
MOSFET turn-on slew rate and VSHW overshoot. RBOOT
values from 0.5 to 3.0 Ω are typically effective in
reducing VSWH overshoot.
VCIN Filter
The VDRV pin provides power to the gate drive of the
high-side and low-side power MOSFET. In most cases,
it can be connected directly to VCIN, the pin that
provides power to the logic section of the driver. For
additional noise immunity, an RC filter can be inserted
between the VDRV and VCIN pins. Recommended
values would be 10 Ω and 1 µF.
Power Loss and Efficiency
Measurement and Calculation
Refer to Figure 32 for power loss testing method.
Power loss calculations are:
PIN=(VIN x IIN) + (V5V x I5V) (W)
(1)
PSW=VSW x IOUT (W)
(2)
POUT=VOUT x IOUT (W)
(3)
PLOSS_MODULE=PIN - PSW (W)
(4)
PLOSS_BOARD=PIN - POUT (W)
(5)
EFFMODULE=100 x PSW/PIN (%)
(6)
EFFBOARD=100 x POUT/PIN (%)
(7)
Figure 31. Block Diagram With VCIN Filter
Figure 32. Power Loss Measurement
© 2011 Fairchild Semiconductor Corporation
FDMF6833C • Rev. 1.0.4
15
www.fairchildsemi.com
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