IR3502MTRPBF International Rectifier, IR3502MTRPBF Datasheet - Page 24

• Manufacturer Part Number: IR3502MTRPBF
• Description: IC XPHASE3 CONTROLLER 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3502MTRPBF

• Applications: Processor
• Current - Supply: 8mA
• Voltage - Supply: 8 V ~ 16 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 32-MLPQ
• 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
• Other names: IR3502MTRPBFTR

IR3502
latch is set. A high level at the VRRDY pin indicates that the converter is in operation and has no fault, but does not
ensure the output voltage is within the specification. Output voltage regulation within the design limits can logically
be assured however, assuming no component failure in the system.
Open Voltage Loop Detection
The output voltage range of error amplifier is detected all the time to ensure the voltage loop is in regulation. If any
fault condition forces the error amplifier output above VCCL-1.08V for 8 switching cycles, the fault latch is set. The
fault latch can only be cleared by cycling power to VCCL.
Open Remote Sense Line Protection
If either remote sense line VOSEN+ or VOSEN- or both are open, the output of remote sense amplifier (VO) drops.
The IR3502 monitors VO pin voltage continuously. If VO voltage is lower than 200 mV, two separate pulse currents
are applied to VOSEN+ and VOSEN- pins respectively to check if the sense lines are open. If VOSEN+ is open, a
voltage higher than 90% of V(VCCL) will be present at VOSEN+ pin and the output of open line detect comparator
will be high. If VOSEN- is open, a voltage higher than 700mV will be present at VOSEN- pin and the output of open-
line-detect comparator will be high. The open sense line fault latch is set, which pulls error amplifier output low
immediately and shut down the converter. The SS/DEL voltage is discharged and the fault latch can only be reset
by cycling VCCL power. During dynamic VID down, OVP may be triggered when output voltage can not follow
VDAC voltage change at light load with large output capacitance. Therefore, over-voltage threshold is raised to
1.73V from VDAC+130mV whenever dynamic VID is detected and the difference between output voltage and VDAC
is more than 50mV, as shown in Figure 17. The over-voltage threshold is changed back to VDAC+130mV if the
difference is smaller than 50mV.
Open Daisy Chain Protection
IR3502 checks the daisy chain every time it powers up. It starts a daisy chain pulse on the PHSOUT pin and detects
the feedback at PHSIN pin. If no pulse comes back after 32 CLKOUT pulses, the pulse is restarted again. If the
pulse fails to come back the second time, the open daisy chain fault is registered, and SS/DEL is not allowed to
charge. The fault latch can only be reset by cycling the power to VCCL.
After powering up, the IR3502 monitors PHSIN pin for a phase input pulse equal or less than the number of phases
detected. If PHSIN pulse does not return within the number of phases in the converter, another pulse is started on
PHSOUT pin. If the second started PHSOUT pulse does not return on PHSIN, an open daisy chain fault is
registered.
Enable Input
The ENABLE pin below 0.8V sets the Fault Latch and a voltage above 0.85V enables the soft start of the converter.
Thermal Monitoring (VRHOT)
A resistor divider including a thermistor at HOTSET pin sets the VRHOT threshold. The thermistor is usually placed
at the temperature sensitive region of the converter, and is linearized by a series resistor. The IR3502 compare
HOTSET pin voltage with a reference voltage of 1.6V. The VRHOT pin is an open-collector output and should be
pulled up to a voltage source through a resistor. If the thermal trip point is reached the VRHOT output drives low.
The hysteresis of the VRHOT comparator helps eliminate toggling of VRHOT output.
The overall system must be considered when designing for OVP. In many cases the over-current protection of the
AC-DC or DC-DC converter supplying the multiphase converter will be triggered and provide effective protection
without damage as long as all PCB traces and components are sized to handle the worst-case maximum current. If
this is not possible, a fuse can be added in the input supply to the multiphase converter.
Page 24 of 39
July 28, 2009