NCP5425_06 ONSEMI [ON Semiconductor], NCP5425_06 Datasheet - Page 11

• Manufacturer Part Number: NCP5425_06
• Description: Dual Synchronous Buck Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Inductor Current Sensing
inductor are shown in Figure 8. Lx is the output inductance
and Rx represents its equivalent series resistance. To
compensate the current sense signal, the values of R1 and C1
are chosen so that Lx/Rx = R1 x C1. With these values, the
Examples of lossless current sensing across an output
Output
Output
DC
Rx
Rx
DC
Switch
Switch
Node
Node
Lx
Lx
R1
C1
R1
C1
R3
(8A)
Rx X I
Rx X I
(8C)
−
−
+
+
L
L
Figure 8. Inductor Current Sensing − Circuit Configurations
+ls
−ls
+ls
−ls
_
_
70 mV
70 mV
+
+
http://onsemi.com
NCP5425
11
Output
current sense signal will have the same wave shape as the
inductor current and the voltage signal on C1 will represent
the instantaneous value of inductor current. The voltage
across C1 can be used as though it were a sense resistor with
the same value as the inductor’s ESR, thus avoiding a sense
resistor’s power loss.
DC
Rx
Output
Switch
Node
DC
Rx
Switch
Lx
Node
Lx
C1
R1
(8D)
R1
C1
R2
R3
(Rx*I
(8B)
(R1 + R2)
Rx*I
R4
L
L
−
) + (E
+
*R2
−
+
+ls
−ls
+ls
−ls
R3
E
R3
)
_
_
70 mV
70 mV
= (Vo*R3)/R3 + R4)
+
+