Datasheet LTM4612 (Analog Devices) - 10

LTM4612
OPERATION Power Module Description
Input filter and noise cancellation circuitry reduce the noise The LTM4612 is a standalone nonisolated switching mode coupling to I/O sides, and ensure the electromagnetic DC/DC power supply. It can deliver 5A of DC output interference (EMI) meets the limits of EN55022 Class B. current with some external input and output capacitors. Pulling the RUN pin below 1V forces the controller into This module provides precisely regulated output voltage its shutdown state, turning off both M1 and M2. At light programmable via one external resistor from 3.3VDC to load currents, discontinuous mode (DCM) operation can 15VDC over a 5V to 36V wide input voltage. The typical be enabled to achieve higher efficiency compared to con- application schematic is shown in Figure 18. tinuous mode (CCM) by setting FCB pin higher than 0.6V. The LTM4612 has an integrated constant on-time current When the DRVCC pin is connected to INTVCC, an integrated mode regulator, ultralow RDS(ON) FETs with fast switching 5V linear regulator powers the internal gate drivers. If a speed and integrated Schottky diodes. The typical switching 5V external bias supply is applied on DRVCC pin, then an frequency is 850kHz at full load at 12V output. With current efficiency improvement will occur due to the reduced power mode control and internal feedback loop compensation, loss in the internal linear regulator. This is especially true the LTM4612 module has sufficient stability margins and at higher input voltages. good transient performance under a wide range of operat- The MPGM, MARG0, and MARG1 pins are used to sup- ing conditions and with a wide range of output capacitors, port output voltage margining, where the percentage of even all ceramic output capacitors. margin is programmed by the MPGM pin, and the MARG0 Current mode control provides cycle-by-cycle fast current and MARG1 select margining. The PLLIN pin provides limiting. Moreover, foldback current limiting is provided in frequency synchronization of the device to an external an overcurrent condition while VFB drops. Internal over- clock. The TRACK/SS pin is used for power supply track- voltage and undervoltage comparators pull the open-drain ing and soft-start programming. PGOOD output low if the output feedback voltage exits a ±10% window around the regulation point. Furthermore, in an overvoltage condition, internal top FET M1 is turned off and bottom FET M2 is turned on and held on until the overvoltage condition clears.
APPLICATIONS INFORMATION
The typical LTM4612 application circuit is shown in Figure
VIN to VOUT Stepdown Ratios
18. External component selection is primarily determined There are restrictions in the maximum V by the maximum load current and output voltage. Refer IN and VOUT step down ratio that can be achieved for a given input voltage. to Table 2 for specific external capacitor requirements for These constraints are shown in the Typical Performance a particular application. Characteristic curve labeled “VIN to VOUT Step-Down Ratio.” Note that additional thermal derating may be ap- plied. See the Thermal Considerations and Output Current Derating section in this data sheet. 4612fc 10 For more information www.linear.com/LTM4612 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 Photograph Related Parts