IRS20955STRPBF International Rectifier, IRS20955STRPBF Datasheet - Page 13

• Manufacturer Part Number: IRS20955STRPBF
• Description: IC DVR DGTL AUDIO PROT 16-SOIC
• Manufacturer: International Rectifier
• Type: MOSFET Driverr

Specifications of IRS20955STRPBF

• Applications: Amplifiers, Receivers
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• For Use With: IRAUDAMP4 - KIT 2CH 120W HALF BRDG AUDIO AMP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Low-Side Over-Current Setting
Let the low-side MOSFET have an R
mΩ and set the current trip level to 30 A. V
given by:
V
Choose R4+R5=10 kΩ to properly load the VREF
pin.
where V
Based on the E-12 series of resistor values, choose
R5 to be 5.6 kΩ and R4 to be 3.9 kΩ to complete
the design.
In general, R
coefficient that needs to be considered when setting
the threshold level. Variations in R
the selection of external or internal component
values.
High-Side Over-Current Sensing
For positive load currents, high-side over-current
sensing also monitors the load condition and shuts
down the switching operation if the load current
exceeds the preset trip level.
www.irf.com
OCSET
= I
TRIP+
REF
= 5.1 V
x R
DS(ON)
DS(ON)
R
=
=
5
5
3
5
=
8 .
0 .
1 .
has a positive temperature
V
REF
OC
V
V
k
= 30 A x 100 mΩ = 3.0 V
V
OCSET
Ω
REF
⋅
10
⋅
k
10
Ω
OCREF
COM
k
5.1V
Figure 13. Low-Side Over-Current Sensing
Ω
R4
R5
DS(ON)
0.5mA
DS(ON)
OCSET
will affect
OCSET
OC Comparator
of 100
+
-
is
IRS20955
LO
OC
High-side
measurement of V
during high-side turn on through pins CSH and VS.
In order to avoid triggering OCP from overshoot, a
blanking interval inserted after HO turn on disables
over-current detection for 450 ns.
In contrast to low-side current sensing, the threshold
at which the CSH pin engages OC protection is
internally fixed at 1.2 V. An external resistive divider
R2 and R3 can be used to program a higher
threshold.
An external reverse blocking diode, D1, is required
to block high voltages from feeding into the CSH pin
while the high-side is off. Due to a forward voltage
drop of 0.6 V across D1, the minimum threshold
required for high-side over-current protection is 0.6
V.
where V
the high-side MOSFET during high-side turn on
V
Since V
drain current I
MOSFET. V
Note: The reverse blocking diode D1 is forward
biased by a 10 kΩ resistor R1 when the high-side
MOSFET is on.
F(D1)
VS
LO
= the forward drop voltage of D1
DS(HIGH SIDE)
DS(HIGH SIDE)
V
V
CSH
current
CSH
CSH
=
=
can be rewritten as:
Q2
R
D
Q1
R
2
2
R
R
DS
+
+
and R
3
IRS20955(S)PbF
+B
3
is determined by the product of
-B
= the drain to source voltage of
R
R
sensing
across the high-side MOFET
3
3
⋅
⋅
(
(
V
R
DS
DS
OUT
DS(ON)
(
HIGHSIDE
(
ON
)
is
⋅
I
)
D
of the high-side
+
+
based
V
V
F
F
(
D
(
D
) 1
) 1
)
)
on
13
the