Datasheet LTM4600HV (Analog Devices) - 9

LTM4600HV
operaTion µModule Description
Q1 is turned off and bottom FET Q2 is turned on and held The LTM4600HV is a standalone non-isolated synchronous on until the overvoltage condition clears. switching DC/DC power supply. It can deliver up to 10A of Pulling the RUN/SS pin low forces the controller into its DC output current with only bulk external input and output shutdown state, turning off both Q1 and Q2. Releasing the capacitors. This module provides a precisely regulated pin allows an internal 1.2µA current source to charge up output voltage programmable via one external resistor the soft-start capacitor. When this voltage reaches 1.5V, from 0.6VDC to 5.0VDC. The input voltage range is 4.5V to the controller turns on and begins switching. 28V. A simplified block diagram is shown in Figure 1 and At low load current the module works in continuous cur- the typical application schematic is shown in Figure 21. rent mode by default to achieve minimum output voltage The LTM4600HV contains an integrated LTC constant ripple. It can be programmed to operate in discontinuous on-time current-mode regulator, ultra-low RDS(ON) FETs current mode for improved light load efficiency when the with fast switching speed and integrated Schottky diode. FCB pin is pulled up above 0.8V and no higher than 6V. The typical switching frequency is 850kHz at full load. The FCB pin has a 4.75k resistor to ground, so a resistor With current mode control and internal feedback loop to VIN can set the voltage on the FCB pin. compensation, the LTM4600HV module has sufficient When EXTV stability margins and good transient performance under a CC pin is grounded or open, an integrated 5V linear regulator powers the controller and MOSFET gate wide range of operating conditions and with a wide range drivers. If a minimum 4.7V external bias supply is ap- of output capacitors, even all ceramic output capacitors plied on the EXTV (X5R or X7R for extended temperature range). CC pin, the internal regulator is turned off, and an internal switch connects EXTVCC to the gate Current mode control provides cycle-by-cycle fast current driver voltage. This eliminates the linear regulator power limit. In addition, foldback current limiting is provided loss with high input voltage, reducing the thermal stress in an over-current condition while VOSET drops. Also, on the controller. The maximum voltage on EXTVCC pin is the LTM4600HV has defeatable short circuit latch off. 6V. The EXTVCC voltage should never be higher than the Internal overvoltage and undervoltage comparators pull VIN voltage. Also EXTVCC must be sequenced after VIN. the open-drain PGOOD output low if the output feedback Recommended for 24V operation to lower temperature voltage exits a ±10% window around the regulation point. in the µModule. Furthermore, in an overvoltage condition, internal top FET 4600hvfe For more information www.linear.com/LTM4600HV 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Simplified Block Diagram Decoupling Requirements Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts