IR3081 International Rectifier Corp., IR3081 Datasheet - Page 14

• Manufacturer Part Number: IR3081
• Description: Xphasetm Vr 10 Control Ic
• Manufacturer: International Rectifier Corp.

Inductor DCR Temperature Correction
If the thermal compensation of the inductor DCR provided by the temperature dependent gain of the current sense
amplifier is not adequate, a negative temperature coefficient (NTC) thermistor can be used for additional correction.
The thermistor should be placed close to the inductor and connected in parallel with the feedback resistor, as
shown in Figure 9. The resistor in series with the thermistor is used to reduce the nonlinearity of the thermistor. A
similar network must be placed on the BBFB to ensure proper operation during a transition to a lower VID code with
Body Braking
Remote Voltage Sensing
To reduce the effect of impedance in the ground plane, the VOSNS- pin is used for remote sensing and connected
directly to the load. The VDAC voltage is referenced to VOSNS- to avoid additional error terms or delay related to a
separate differential amplifier. The capacitor connecting the VDAC and VOSNS- pins ensure that high speed
transients are fed directly into the error amplifier without delay.
Page 14 of 39
TM
.
Figure 9. Temperature compensation of inductor DCR
VDAC
Control IC
VDRP
Amplifier
VDAC
Error
Amplifier
+
-
IFB
Control IC
-
+
Figure 8. Adaptive voltage positioning
AVP
Amplifier
Error
Amplifier
+
-
IFB
VDRP
EAOUT
FB
IIN
-
+
RDRP
RFB
EAOUT
FB
VDRP
IIN
IIN
Vo
ISHARE
VDAC
ISHARE
ISHARE
ISHARE
ISHARE
VDAC
RDRP
RFB2
RFB
Phase IC
Phase IC
10k
10k
Rt
Vo
Current Sense
Amplifier
Current Sense
Amplifier
+
-
+
-
CSIN+
CSIN-
CSIN+
CSIN-
10/01
IR3081
/04