IR3510MTRPBF International Rectifier, IR3510MTRPBF Datasheet - Page 20

• 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

IR3510 THEORY OF OPERATION
Vbias Regulator
The Vbias regulator supplies a 6.8V/20mA bias voltage for internal circuitry, and through VBIAS pin it also provides
reference voltage for Phase IC. Since the oscillator ramp amplitude tracks the VBIAS voltage, it should be used to
program the Phase IC trip points to minimize phase delay errors.
The VBIAS can also be used as system reference voltage to set VSET, OCPSET and OVPSET voltage.
Charge Pump
The Charge Pump provides gate drive voltage for
input soft-start FET and output ORing FET. A
Tripler circuit is used to boost the VCC voltage to a
high-level voltage in order to drive the input FET.
It has internal voltage clamp of 27V. It provides
20uA input FET charge current and 10uA Oring
FET charge current. It also supplies the internal
input OC comparator and OCP regulator.
An external cap of 0.1uF/50V voltage is required.
Fig. 6 shows the charge pump voltage vs. Vcc.
Input FET Soft-Start Regulator
The input FET soft-start regulator compares the voltage after the input FET and the voltage on the soft-start cap,
which is externally connected on the “SS” pin, and then adjusts the input FET gate drive voltage to control the
P12V, which is the voltage after the input FET, to follow the soft-start cap voltage and linearly increase until it reach
the input voltage.
Since the input FET soft-start regulator can only sink current, it can only slow down the ramp of the input FET gate
drive voltage. If the soft-start cap is too small, or the input FET gate capacitance is large enough, the P12V voltage
may not be able to follow the soft-start cap.
GATE_I
VIN
VCX
SS
Page 20 of 36
Fig. 7 Soft-Start Regulator
Css
0.1uF
65mv
-
+
20uA
70uA
INPUT SS REGULATOR
OFF
-
+
36K
10K
IR Confidential
P12V
ICS+
Vcx (V)
30
25
20
15
10
5
0
8
IR3510 Charge Pump Voltage
Fig. 8 Input FET Soft-Start
Fig. 6 Charge Pump Voltage
10
12
Vin (V)
14
May 18, 2009
16
IR3510
18