IRS20954SPBF International Rectifier, IRS20954SPBF Datasheet - Page 14

• Manufacturer Part Number: IRS20954SPBF
• Description: IC AMP DGTL AUDIO PROT 16-SOIC
• Manufacturer: International Rectifier
• Type: MOSFET Driverr

Specifications of IRS20954SPBF

• Applications: Amplifiers, Receivers
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Since the sensed voltage of V
respect to COM for a trip level I
V
In order to neglect the input bias current of OCSET pin, it is recommended to use 10 kΩ total for R4 and R5 to drain 0.5 mA
through the resistors.
For the positive load current, high-side over-current sensing monitors over load condition by measuring V
pins and shutdown the operation. The CSH pin is to detect the drain-to-source voltage refers to the V
of the high-side MOSFET. In order to neglect overshoot ringing at the switching edges, CSH sensing circuitry starts monitoring
after the first 300 ns the HO is on by blanking the signal from CSH pin.
In contrast to the low-side current sensing, the threshold of CSH pin to engage 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 to block high voltage feeding into the CSH pin while high-side is off. By subtracting a
forward voltage drop of 0.6 V at D1, the minimum threshold which can be set in the high-side is 0.6 V across the drain to
source.
With the configuration in Fig. 14, the voltage in CSH is:
Since V
as:
The reverse blocking diode D1 is forward biased by a 10 kΩ resistor R1 when the high-side MOSFET is on.
www.irf.com
V
V
Where:
R
R
OCSET
CSH
CSH
2
3
V
VF
=
DS(HIGH-SIDE)
=
=
(D1)
V
Vth
R
DS
= V
R
DS(HIGH-SIDE)
2
is the forward drop voltage of D1
2
+
OCH
High-side Over-Current Sensing
R
+
R
3
V
+
DS(LOW-SIDE)
R
3
F
R
3
−
3
⋅
1
(
V
⋅
is drain to source voltage of the high-side MOSFET in its ON state
(
DS
R
DS
(
HIGHSIDE
is determined by the product of drain current I
(
ON
= I
)
⋅
TRIP+
)
I
D
+
V
+
F
V
x R
(
D
Not recommended for new designs.
F
TRIP+
) 1
S
(
D
)
DS(ON)
) 1
is compared with the voltages fed to the OCSET pin, the required voltage of OCSET with
)
is:
Please use IRS20957SPBF.
Figure 13: Low-Side Over-Current Sensing
D
and R
DS(ON)
in the high-side MOSFET. V
IRS20954SPBF
S
pin which is the source
DS
CSH
with CSH and Vs
can be written
14