IR3510MTRPBF International Rectifier, IR3510MTRPBF Datasheet - Page 24

• 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

Current Error Amplifier
The voltage error amplifier output, IREF, is connected to the non-inverting input of the current error amplifier. The
current report output, IO, is connected to the “IFB” pin through a feedback resistor, and then connected to the
inverting input of the current error amplifier.
The voltage error amplifier has minimum output voltage since it is powered from a single power supply. In order to
keep the current error amplifier under control at no-load condition, a 300mv offset is added to the current feedback
input of the current error amplifier, as seen in Fig. 12.
Constant Current Limit
Constant current limit function is required for paralleled redundant system. With average current mode control, the
constant current limit can be easily implemented by clamping the current reference signal, which is the output of
voltage error amplifier and also the non-inverting input of the current error amplifier.
An OC clamping amplifier is used to buffer the “OCPSET” voltage from the system. Its output is connected together
with the current reference signal, so it clamps the current reference voltage to be no more than the “OCPSET”
voltage. To compensate the 300mv offset voltage in the current feedback signal, a same 300mv offset voltage is
added to the OC clamp amplifier input.
Remote Voltage Sense Amplifier
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.
Since the remote voltage sense amplifier has limited input impedance, any impedance in series with the remote
sense lines will affect the voltage sense accuracy. If a voltage feedback divider is needed to match the VSET
voltage, it’s better to place the voltage divider at the remote sense amplifier output, that is, “VO” pin.
ORing Comparator and Oring FET Driver
The Oring comparator monitors the voltage across the
Oring FET, which is produced by the current going
through the Rds(on) of the Oring FET.
Oring FET is turned once it develops positive voltage
from SOURCE to DRAIN. Since the Oring FET gate
charge current from the Charge Pump is only 10uA, it
takes some time to fully turn on the Oring FET. An
internal
“GATE_O” to Vcc to speed up the Oring FET turn-on.
When a negative voltage is detected and it is exceed
the threshold voltage set by the programming resistor in
series with the “OR-“ pin, the “GATE_O” is quickly
pulled down with 2A peak discharge current.
A 30mv hesteresis is added to the Oring comparator to prevent it from chattering and ensure it is only turned
off with negative input. The current source flowing into the “IR-“ pin, which is used to program the reverse
current cut-off threshold through an external resistor, is determined by the switching frequency in order to
achieve good accuracy. It increases with the switching frequency.
An open-collector output “ORING” signal indicates the Oring FET status. HIGH means the Oring FET has
positive load current, and LOW means the Oring FET is OFF or carrying negative current.
Page 24 of 36
3K
pull-up
resistor
is
connected
IR Confidential
from
ig.
Vout+
OR+
OR-
Charge Pump
IROSC
VR Fault
Vcc
10uA
3K
20uA
VIDSEL
Fig. 13 Oring Comparator
ORING
COMPARATOR
-
+
Rrcset
May 18, 2009
IR3510
ORING
GATE_O
Vout