IR3513ZMTRPBF International Rectifier, IR3513ZMTRPBF Datasheet - Page 17

• Manufacturer Part Number: IR3513ZMTRPBF
• Description: IC CTRL XPHASE3 POL 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3513ZMTRPBF

• Applications: Processor
• Current - Supply: 3mA
• Voltage - Supply: 8 V ~ 16 V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: *
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

NOT RECOMMENDED FOR NEW DESIGNS
IR3513
REPLACEMENT PRODUCT – IR3513ZMTRPBF
VREF Control
The MARGIN input comparators monitor the MARGIN pin and control the internal reference voltage whose output is
sent to the VREF buffer amplifier. The output of the buffer amplifier is the VREF pin. The VREF voltage, input
offsets of error amplifier and remote sense differential amplifier are post-package trimmed to provide 0.8% system
set-point accuracy. The actual VREF voltage does not determine the system accuracy, which has a wider
tolerance.
The IR3513 can accept changes in the MARGIN input while operating and vary the VREF voltage accordingly. The
slew rate of the voltage at the VREF pin can be adjusted by an external capacitor between VREF pin and LGND
pin. A resistor connected in series with this capacitor is required to compensate the VREF buffer amplifier. Margin
transitions result in a smooth analog transition of the VREF voltage and converter output voltage minimizing inrush
currents in the input and output capacitors and overshoot of the output voltage.
Remote Voltage Sensing
VOSEN+ and VOSEN- are used for remote sensing and are 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 IR3513 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 (typical) and discharge current of 4.5uA (typical) control the up
and down slope of the voltage at the SS/DEL pin respectively.
Figure 8 shows normal converter start-up. If there is no fault, the SS/DEL pin will start charging. The error amplifier
output EAOUT is clamped low until SS/DEL reaches 1.4V. The error amplifier will then regulate the converter’s
output voltage to match the SS/DEL voltage, less the 1.4V offset, until the converter output reaches the level
determined by the VREF (0.8 V typically) inputs. The SS/DEL voltage continues to increase until it rises above
3.12V and allows the PG signal to be asserted. SS/DEL finally settles at 3.2V indicating the end of the soft start.
VCCL under voltage lock out, over current, as well as a low signal on the ENABLE input immediately sets the fault
latch, which causes the EAOUT pin to drive low turning off the phase IC drivers. The PG pin also drives low, and
SS/DEL begins to discharge until the voltage reaches 0.2V. If the fault has cleared the fault latch will be reset by the
discharge comparator allowing a normal soft start to occur.
Other fault conditions, such as over voltage, open sense lines, and open daisy chain, set different fault latches,
which start discharging SS/DEL, pull down EAOUT voltage and drive PG low. However, the latches can only be
reset by cycling VCCL power.
If SS/DEL pin is pulled below 0.7V, the converter can be disabled.
Page 17
May 11, 2008