IR3510MTRPBF International Rectifier, IR3510MTRPBF Datasheet - Page 29

• 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

The VRRDY goes HIGH when the soft-start cap voltage reaches the charge-up comparator threshold, which is
3.7V. The total soft-start time from Enable going HIGH to VRRDY going HIGH is determined by,
The soft-start cap can be selected by one of the above equation based on which soft-start time needs to be met.
Input OCP setting resistor
The input current is sensed by a sense resistor placed after and in series with the input FET. The input OCP
setting resistor is connected between the downstream of the input sense resistor and the “ICS-“ pin. A typical
22uA current source flowing out of the “ICS-“ pin goes through Rocset and sets the input current limit threshold
voltage.
The severe OCP threshold voltage is 60mv more than the normal current limit threshold, which gives,
A 10nF cap Cics is recommended between “ICS+” and “ICS-“ pins and placed close to the IC.
IOCD Cap
The IOCD cap programs the input OCP time-out delay. When the sensed input current reaches the input OCP
threshold, the internal 20uA current source starts charging the IOCD cap, and once the IOCD cap voltage is
charged above 0.85V, which is the time-out comparator threshold, the input FET is latch OFF.
The time-out delay time can be calculated as,
Current Error Amplifier Compensation
Average current mode control is used to implement the constant current limit function and keep good current
sharing between modules. One added benefit of using current mode control is that it can eliminate the output
inductor from the voltage loop and make the voltage loop compensation much simple.
The inputs to the current error amplifier are the voltage error amplifier output, which serves as the current
reference signal, and the inductor current sense feedback signal. The open current loop gain is determined by the
PWM gain for the power stage, the output inductor, the output cap and the load resistor. The open current loop
has one output zero made by the output cap and the load resistor, and the L-C double-pole. The output zero
frequency is usually smaller than the L-C resonant frequency Fo, which means the current loop can have enough
phase margin.
Page 29 of 36
Tos
Tocd
Tor
Iocset
Isevere
=
=
=
C
C
=
=
C
SS
SS
I
Rocset
CHG
iocd
Rocset
*
( *
I
3
CHG
VFB
*
7 .
I
IR Confidential
CHG
. 0
=
*
85
Rs
*
22
−
C
70
22
. 1
=
SS
*
*
35
*
10
C
*
10
10
20
Rs
iocd
)
3
−
7 .
−
6
=
−
6
*
6
*
10
C
+
. 0
SS
−
60
85
6
( *
70
*
VFB
10
*
10
−
3
−
−
6
. 1
35
)
May 18, 2009
IR3510