IR5001S データシートの表示（PDF） - International Rectifier
部品番号
コンポーネント説明
メーカー
IR5001S Datasheet PDF : 12 Pages
| |||
IR5001S & (PbF)
APPLICATION INFORMATION
The IR5001S is designed for multiple active ORing
and reverse polarity protection applications with
minimal number of external components. Examples
of typical circuit connections are shown below.
Negative Rail ORing/Reverse Polarity Protection
A typical connection of the IR5001S in negative
rail Active ORing or reverse polarity protection is
shown in Fig. 17. In this example, IR5001S is biased
directly from the positive rail. However, any of the
biasing schemes shown in Fig. 16 can be used.
For input ORing in carrier-class communications
boards, one IR5001S is used per feed. This is
shown in Fig.1. An evaluation kit is available for
typical system boards, with input voltages of
negative 36V to negative 75V, and for power levels
from 30W to about 300W. The p/n for the evaluation
kit is IRDC5001-LS48V. This evaluation kit contains
detailed design considerations and in-circuit
performance data for the IR5001S.
Vin +
Rbias
+
Vbias
IR5001
Vline
OUT
Vcc
Gnd
FETch
INN
FETst
INP
Load
Vin -
Redundant Vin -
Figure. 17 Connection of INN, INP, and Gnd for negative
rail Active ORing or reverse polarity protection.
Vout +
Redundant Vout +
Rbias
+
Vbias
Vout -
IR5001
Vline
OUT
Vcc
Gnd
FETch INN
FETst
INP
Load
Figure. 18. Connection of INN,INP, and Gnd when the
MOSFET is placed in the path of positive rail.
Positive Rail ORing / Ground ORing in
Communications Boards
An example of a typical connection in positive
rail ORing is shown in Fig. 18. Typical applications
are inside redundant AC-DC and DC-DC power
supplies, or on-board ORing. For positive rail ORing,
an additional Vbias voltage above the positive rail is
needed to bias the IR5001S.
An evaluation kit for high-current 12V positive
rail ORing is available under p/n IRAC5001-
HS100A, demonstrating performance of the
IR5001S at 100A output current.
Considerations for the Selection of the Active
ORing N-Channel MOSFET
Active ORing FET losses are all conduction
losses, and depend on the source-drain current and
RDS(on) of the FET. The conduction loss could be
virtually eliminated if a FET with very low RDS(on)
was used. However, using arbitrarily low RDS(on) is
not desirable for three reasons:
1. Turn off propagation delay. Higher RDS(on) will
provide more voltage information to the internal
comparator, and will result in faster FET turn off
protection in case of short-circuit of the source
(less voltage disturbance on the redundant bus).
2. Undetected reverse (drain to source) current
flow. With the asymmetrical offset voltage, some
small current can flow from the drain to source
of the ORing FET and be undetected by the
IR5001S. The amount of undetected drain-
source current depends on the RDS(on) of the
selected MOSFET and its RDS(on). To keep the
reverse (drain-source) current below 5 – 10% of
the nominal source-drain state, the RDS(on) of
the selected FET should produce 50mV to
100mV of the voltage drop during nominal
operation.
3. Cost. With properly selected RDS(on), Active
ORing using IR5001S can be very cost
competitive with traditional ORing while
providing huge power loss reduction. For
example, a FET with 20mOhm RDS(on) results in
60mV voltage drop at 3A; associated power
savings compared to the traditional diode ORing
(assuming typical 0.6V forward voltage drop) is
ten fold(0.18W vs. 1.8W)! Now assume that
FET RDS(on) was 10mOhm. The power loss
would be reduced by additional 90mW, which is
negligible compared to the power loss reduction
already achieved with 20mOhm FET. But to get
this negligible saving, the cost of the Active
ORing FET would increase significantly.
www.irf.com
10
Share Link: 