ir3500a International Rectifier Corp., ir3500a Datasheet - Page 19

• Manufacturer Part Number: ir3500a
• Description: Xphase3 Vr11.0 & Amd Pvid Control Ic
• Manufacturer: International Rectifier Corp.

Remote Voltage Sensing
VOSEN+ and VOSEN- are used for remote sensing and connected directly to the load. The remote sense
differential amplifier with high speed, low input offset and low input bias current ensures accurate voltage sensing
and fast transient response.
Start-up Sequence
The IR3500A has a programmable soft-start function to limit the surge current during the converter start-up. A
capacitor connected between the SS/DEL and LGND pins controls soft start timing, over-current protection delay
and hiccup mode timing. A charge current of 52.5uA and discharge current of 4uA control the up slope and down
slope of the voltage at the SS/DEL pin respectively.
Page 19 of 47
Figure 10 - Temperature compensation of inductor DCR
IVSETPT
Remote
Sense
Amplifier
IVSETPT
Control IC
Remote
Sense
Amplifier
VDAC
VDRP
Amplifier
Error
Amplifier
+
-
Figure 9 - Adaptive voltage positioning
Control IC
-
+
+
-
VDAC
VDRP
Amplifier
Error
Amplifier
+
-
VSETPT
EAOUT
VDRP
FB
VDAC
IIN
VO
VOSEN+
VOSEN-
-
+
+
-
RDRP
RSETPT
RFB
VSETPT
EAOUT
VDAC
FB
VDRP
IIN
VO
VOSEN+
VOSEN-
RSETPT
ISHARE
VDAC
ISHARE
VDAC
RDRP
RFB1
Phase IC
Phase IC
RFB
3k
3k
Rt
Current Sense
Amplif ier
Current Sense
Amplif ier
+
-
+
-
CSIN+
CSIN-
CSIN+
CSIN-
July 3, 2008
IR3500A