Datasheet LTM4625 (Analog Devices) - 8

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OPERATION
The LTM4625 is a standalone nonisolated switch mode DC/ regulation point. Continuous operation is forced during OV DC power supply. It can deliver up to 5A DC output current and UV condition except during start-up when the TRACK with few external input and output capacitors. This module pin is ramping up to 0.6V. provides precisely regulated output voltage adjustable Furthermore, in order to protect the internal power MOSFET between 0.6V to 5.5V via one external resistor over a 4V devices against transient voltage spikes, the LTM4625 to 20V input voltage range. With an external bias supply constantly monitors the V above 4V connected to SV IN pin for an overvoltage condi- IN, this module operates with tion. When V an input voltage down to 2.375V. The typical application IN rises above 23.5V, the regulator suspends operation by shutting off both power MOSFETs. Once V schematic is shown in Figure 20. IN drops below 21.5V, the regulator immediately resumes The LTM4625 contains an integrated constant on-time normal operation. The regulator does not execute its valley current mode regulator, power MOSFETs, inductor, soft-start function when exiting an overvoltage condition. and other supporting discrete components. The default Multiphase operation can be easily employed with the switching frequency is 1MHz. For switching noise-sensitive synchronization and phase mode controls. Up to 12 phases applications, the switching frequency can be adjusted can be cascaded to run simultaneously with respect to by external resistors and the μModule regulator can be each other by programming the PHMODE pin to different externally synchronized to a clock within ±30% of the set levels. The LTM4625 has CLKIN and CLKOUT pins for frequency. See the Applications Information section. PolyPhase operation of multiple devices or frequency With current mode control and internal feedback loop synchronization. compensation, the LTM4625 module has sufficient stabil- Pulling the RUN pin below 1.1V forces the controller into ity margins and good transient performance with a wide its shutdown state, turning off both power MOSFETs range of output capacitors, even with all ceramic output and most of the internal control circuitry. At light load capacitors. currents, discontinuous mode (DCM) operation can be Current mode control provides cycle-by-cycle fast cur- enabled to achieve higher efficiency compared to continu- rent limiting. Foldback current limiting is provided in an ous mode (CCM) by pulling the MODE pin to SGND. The overcurrent condition indicated by a drop in VFB reducing TRACK/SS pin is used for power supply tracking and inductor valley current to approximately 40% of the origi- soft-start programming. See the Applications Informa- nal value. Internal output overvoltage and undervoltage tion section. comparators pull the open-drain PGOOD output low if the output feedback voltage exits a ±10% window around the Rev D 8 For more information www.analog.com Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Decoupling Requirements Operation Applications Information Package Description Revision History Package Photo Design Resources Related Parts