irs20954s International Rectifier Corp., irs20954s Datasheet - Page 15

• Manufacturer Part Number: irs20954s
• Description: Protected Digital Audio Driver
• Manufacturer: International Rectifier Corp.

OCP Design Example
Fig. 14 demonstrates the typical peripheral circuit of high side current sensing. For example, the over-current protection level is
set to trip at 30 A with a MOSFET with R
Choose R2+R3=10 k , thus
Vth
V
V
D1. T
R2 = 6.8 k:
R3 = 3.3 k:
The reverse blocking diode D1 is determined by voltage rating and speed. To block bus voltage, reverse voltage has to be
higher than (+B)-(-B). Also the reverse recovery time needs to be as fast as the bootstrap charging diode. The Philips BAV21W,
200 V, 50 ns high speed switching diode, is more than sufficient.
www.irf.com
R
DS
F
3
= 0.6 V
OCL
is the voltage drop at I
10
he values of R2 and R3 from the E-12 series are:
k
= 1.2 V
:
V
DS@ID=30A
V
Vth
DS
OCH

V
High Side Over-current Setting
Choosing the Right Reverse Blocking Diode
F
Comparator
OC
= 100 m x 30 A = 3 V
CSH
D
=30 A across R
R
+
-
1.2V
3
Figure 14: Programming High Side Over-Current Threshold
IRS20954
10
k
:
HO
DS(ON)

DS(ON)
R
2
of 100 m , the component values of R2 and R3 are calculated as:
.
of the high side MOSFET. V
CSH
HO
VB
VS
LO
\
R3
R2
Vcc
R1
F
D1
is a forward voltage of reverse blocking diode,
Q2
Q1
+B
-B
OUT
IRS20954S
15