IR3510MTRPBF International Rectifier, IR3510MTRPBF Datasheet - Page 23

• Manufacturer Part Number: IR3510MTRPBF
• Description: IC XPHASE CONTROL 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase™r

Specifications of IR3510MTRPBF

• Applications: Processor
• Mounting Type: Surface Mount
• Package / Case: 32-MLPQ
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Voltage - Supply: -
• Operating Temperature: -
• Other names: IR3510MTRPBFTR

VREF Buffer
The “VSET” pin inputs the VSET voltage from the system, and it is connected to the input of the VREF buffer. The
buffered VSET voltage, VREF, is used as the reference voltage of the voltage error amplifier to control the voltage
regulator output voltage. It’s is also used by the “Body Braking” comparator as a threshold voltage.
The VREF is one of the 5-wire buses connected to the phase IC. It is used as the offset voltage of the current sense
signal IIN, and also the floor voltage of the PWM ramp.
Voltage Error Amplifier
The VRF reference voltage is connected to the non-
inverting input of the voltage error amplifier. The soft-
start clamping circuit is also connected to the non-
inverting input to control the voltage EA output during
soft-start.
Connected to the inverting input of the voltage error
amplifier is the output feedback voltage, which comes
directly from the remote voltage sense amplifier output
or through a resistor divider.
Typical Type II or Type III can be used to compensate
the voltage loop. The Rdroop is used to set the output
voltage droop or the load line, the Rc and Cc is used to
set the compensation zero, and Cp is used to set the
high-frequency pole.
Current Report Amplifier
Three-stage amplifiers are used to report the output load current through “IO” pin. The “IO” signal is also used to set
the voltage droop and balance the current between voltage regulators. Since the current sense signal from the
phase IC has an offset voltage of VREF, the first stage is a differential amplifier which subtracts the VREF voltage
from the IIN signal. In order to measure the reverse current in a paralleled system, a 200mv fixed offset voltage is
added to the current sense signal in a second-stage amplifier. A non-inverting third-stage amplifier with external
gain setting resistors is used to program its output voltage to be proportional to the output load current.
A NTC thermistor is normally required to compensate the TC effect of the inductor DCR current sensing. Fig.12
shows the current report amplifiers and its typical thermal compensation circuit.
Page 23 of 36
OCPSET
Fig. 12 Current Report with Thermal Compensation and Current Error Amplifier
VREF
IGAIN
IREF
IFB
IIN
CURRENT REPORT AMP.
0.2V
0.3V
OC CLAMP
+
VIDSEL
-
+
VIDSEL
-
IR Confidential
+
-
CURRENT ERROR
+
-
0.3V
R1
SS
VFB
R5
R3
R6
R2
AMPLIFIER
Fig. 11
SOFT START
CLAMP
C2
+
-
R4
1.4V
C1
VREF
10K NTC
Rf b
Voltage Error Amplifier
VOLTAGE ERROR
AMPLIFIER
EAOUT
IO
+
+
-
May 18, 2009
Rc
Cp
Rdroop
IR3510
Cc
IREF
VFB