NCP4547IMNTWG ON Semiconductor, NCP4547IMNTWG Datasheet - Page 8

• Manufacturer Part Number: NCP4547IMNTWG
• Description: Power Switch ICs - Power Distribution BDS2 MCM PACKAGED
• Manufacturer: ON Semiconductor

On−Resistance
a charge pump in the controller circuit. The output voltage
of the charge pump is dependent on the voltage on V
R
must be taken to ensure a sufficient V
create the desired R
Enable Control
an active-high or active-low configuration. When the EN
and POL pins are both at a logic high level or both at a logic
low level and the V
applied, the MOSFET will be enabled. Similarly, when the
EN and POL pins are at different logic levels, the MOSFET
will be disabled.
internal pull up resistor on the POL pin ensure that the
MOSFET will be disabled when neither pin is driven. The
internal pull down or pull up resistor can also be used to
allow for only one of the pins to be driven in either an
active-high or active-low state.
Parametric Adjustments
depending on the need to control turn-on delay, slew rate, and
bleed resistance. Default minimum values of each parameter
are built into the part without the requirement of external
components. This configuration is shown above in Figure 1.
external components are used to modify the turn-on delay,
slew rate, and total bleed resistance.
connected from the V
pins. This allows for one external capacitor to be used to
modify the turn-on delay and slew rate. Note that the value
of C
C
independent control of the turn-on delay and slew rate.
Turn−On Delay
transitions on EN (or POL) to the MOSFET turning on. The
10. Recommended range, larger values may be used but may degrade the performance of the part
SLEW RATE AND TURN−ON DELAY
ON
DEL
Turn−on Delay Constant
External Delay Capacitance (Note 10)
Slew Rate Constant
External Slew Rate Capacitance (Note 10)
Internal Slew Rate Capacitance
External Combo Capacitance (Note 10)
The MOSFET gate voltage in the NCP4547 is driven by
The NCP4547 allows for enabling the MOSFET in either
An internal pull down resistor on the EN pin and an
The NCP4547 can be used in several configurations
Figures 22 and 23 show alternate configurations where
Figure 22 shows an external capacitor, C
Figure 23 shows the use of two external capacitors for
The NCP4547 provides a time delay between the input
COMBO
of the MOSFET is in turn dependent on its V
and C
is used in Equations 1 and 2 (below) in place of
SR
respectively.
Parameter
ON
CC
OUT
given the anticipated input voltage.
supply pin has an adequate voltage
pin to both the DELAY and SR
CC
voltage is used to
APPLICATIONS INFORMATION
Between DEL pin and GND
Between SR pin and V
Between SR & DEL pins and V
GS
COMBO
CC
http://onsemi.com
. Care
. The
Conditions
,
8
turn-on delay can be increased with an external capacitor
added between the DELAY pin and either ground or the
V
delay to a delta term which is calculated as follows:
where K
capacitance added between the DELAY pin to either ground
or the V
capacitor is present, the delay will be the specified default
turn-on delay.
Slew Rate Control
rate which provides soft start functionality. This limits the
inrush current caused by capacitor charging and enables this
device to be used in hot swapping applications. The slew rate
can be decreased with an external capacitor added between
the SR pin and the V
where K
added between the SR pin and the V
the on-chip capacitance (see table below). Note that this
equation is only valid for C
capacitor is present, the slew rate will be the specified
default slew rate.
Load Bleed
used to bleed the charge off of the load to ground after the
MOSFET has been disabled. In series with the bleed resistor
is a bleed switch which is enabled whenever the MOSFET
is disabled. Delays are added to the enable of this switch to
ensure that both the MOSFET and the bleed switch are not
concurrently active. The total bleed resistance can be
increased by adding a resistor between the BLEED pin and
the V
bleed function is not desired, the BLEED pin should be tied
to ground or left floating.
OUT
OUT
The total delay is calculated by adding the default turn-on
The NCP4547 is equipped with controlled output slew
The slew rate can be calculated as follows:
The NCP4547 has an on−chip bleed resistor that can be
pin
OUT
pin as shown in Figures 22 and 23.
OUT
SR
DEL
OUT
pin as shown in Figures 22 and 23. If the load
is a constant, C
pin
is a constant and C
pin (see table below). When no external
C
SR +
Symbol
OUT
Dt + K
C
C
COMBO
K
K
C
CHIP
DEL
DEL
SR
SR
pin as shown in Figures 22 and 23.
C
DEL
SR
SR
SR
K
) C
≥ 470 pF. When no external
Min
* C
is the off-chip capacitance
SR
DEL
CHIP
OUT
DEL
1.65
1.43
Typ
150
pin, and C
is the off-chip
Max
10
2
2
CHIP
(eq. 1)
(eq. 2)
Unit
MW
nF
mA
nF
pF
nF
is