IR3522 International Rectifier, IR3522 Datasheet - Page 22

• Manufacturer Part Number: IR3522
• Description: DDR & VTT CONTROL IC
• Manufacturer: International Rectifier

IR3522
turn-on within approximately 150ns. The low side MOSFET will remain low until the over voltage fault condition latch
cleared. This latch is cleared by cycling the ENABLE pin or the VID_OFF command.
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 thus providing 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.
Open Remote Sense Line Protection
If either remote sense line VOSEN
+ or VOSEN
- is open, the output of Remote Sense Amplifier (VOUT
) drops.
X
X
X
The IR3522 continuously monitors the VOUT
pin and if VOUT
is lower than 200 mV, two separate pulse currents
X
X
are applied to the VOSEN
+ and VOSEN
- pins to check if the sense lines are open. If VOSEN
+ is open, a voltage
X
X
X
higher than 90% of V(VCCL) will be present at VOSEN
+ pin and the output of Open Line Detect Comparator will
X
be high. If VOSEN
- is open, a voltage higher than 400mV will be present at VOSEN
- pin and the Open Line
X
X
Detect Comparator output will be high. With either sense line open, the Open Sense Line Fault Latch will be set to
force the error amplifier output low and immediately shut down the converter. SS/DEL will be discharged and the
Open Sense Fault Latch can only be reset by cycling the ENABLE pin or the VID_OFF command.
Open Daisy Chain Protection
The IR3522 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 30 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
X
to charge. The fault latch can only be reset by cycling the ENABLE pin or the VID_OFF command.
After powering up, the IR3522 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.
Phase Number Determination
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After a daisy chain pulse is started, the IR3522 checks the timing of the input pulse at PHSIN pin to determine the
phase number.
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