Datasheet LTM4602HV (Analog Devices) - 8

LTM4602HV
U OPERATIO µModule Description
in an overvoltage condition, internal top FET Q1 is turned off and bottom FET Q2 is turned on and held on until the The LTM4602HV is a standalone non-isolated synchronous overvoltage condition clears. switching DC/DC power supply. It can deliver up to 6A of DC output current with only bulk external input and output Pulling the RUN/SS pin low forces the controller into its capacitors. This module provides a precisely regulated shutdown state, turning off both Q1 and Q2. Releasing the output voltage programmable via one external resistor from pin allows an internal 1.2µA current source to charge up 0.6VDC to 5.0VDC. The input voltage range is 4.5V to 28V. the softstart capacitor. When this voltage reaches 1.5V, A simplifi ed block diagram is shown in Figure 1 and the the controller turns on and begins switching. typical application schematic is shown in Figure 21. At low load current the module works in continuous cur- The LTM4602HV contains an integrated LTC constant rent mode by default to achieve minimum output voltage on-time current-mode regulator, ultra-low RDS(ON) FETs ripple. It can be programmed to operate in discontinuous with fast switching speed and integrated Schottky diode. current mode for improved light load effi ciency when the The typical switching frequency is 800kHz at full load. FCB pin is pulled up above 0.8V and no higher than 6V. With current mode control and internal feedback loop The FCB pin has a 10k resistor to ground, so a resistor to compensation, the LTM4602HV module has suffi cient VIN can set the voltage on the FCB pin. stability margins and good transient performance under a When EXTV wide range of operating conditions and with a wide range CC pin is grounded or open, an integrated 5V linear regulator powers the controller and MOSFET gate of output capacitors, even all ceramic output capacitors drivers. If a minimum 4.7V external bias supply is ap- (X5R or X7R). plied on the EXTVCC pin, the internal regulator is turned Current mode control provides cycle-by-cycle fast current off, and an internal switch connects EXTVCC to the gate limit. In addition, foldback current limiting is provided driver voltage. This eliminates the linear regulator power in an over-current condition while VFB drops. Also, the loss with high input voltage, reducing the thermal stress LTM4602HV has defeatable short circuit latch off. Internal on the controller. The maximum voltage on EXTVCC pin is overvoltage and undervoltage comparators pull the open- 6V. The EXTVCC voltage should never be higher than the drain PGOOD output low if the output feedback voltage exits VIN voltage. Also EXTVCC must be sequenced after VIN. a ±10% window around the regulation point. Furthermore, Recommended for 24V operation to lower temperature in the µModule. 4602hvf 8