Datasheet LTM4649 (Analog Devices) - 10

LTM4649
OPERATION Power Module Description
The LTM4649 is internally compensated to be stable over The LTM4649 is a high performance single output stand- all operating conditions. Table 3 provides a guideline for alone nonisolated switching mode DC/DC power supply. input and output capacitances for several operating condi- It can provide up to 10A output current with few exter- tions. LTpowerCAD™ is available for transient and stability nal input and output capacitors. This module provides analysis. The VFB pin is used to program the output voltage precisely regulated output voltage programmable via with a single external resistor to ground. an external resistor from 0.6VDC to 3.3VDC over a 4.5V A remote sense amplifier is provided in the LTM4649 for to 16V input range. The typical application schematic is accurately sensing output voltages ≤3.3V at the load point. shown in Figure 17. Multiphase operation can be easily employed with the The LTM4649 has an integrated constant-frequency cur- synchronization inputs using an external clock source. rent mode regulator, power MOSFETs, inductor, and other See application examples. supporting discrete components. The typical switching High efficiency at light loads can be accomplished with frequency is 450kHz. For switching noise-sensitive ap- selectable Burst Mode operation using the MODE pin. These plications, it can be externally synchronized from 400kHz light load features will accommodate battery operation. to 800kHz. See the Applications Information section. Efficiency graphs are provided for light load operation in With current mode control and internal feedback loop the Typical Performance Characteristics section. compensation, the LTM4649 module has sufficient stabil- A TEMP pin is provided to allow the internal device tem- ity margins and good transient performance with a wide perature to be monitored using an onboard diode connected range of output capacitors, especially with all ceramic PNP transistor. This diode connected PNP transistor is output capacitors. grounded in the module and can be used as a general Current mode control provides cycle-by-cycle fast current temperature monitor using a device that is designed to limit in an overcurrent condition. An internal overvoltage monitor the single-ended connection. monitor protects the output voltage in the event of an The switching node pin is available for functional opera- overvoltage >10%. The top MOSFET is turned off and the tion monitoring. A resistor-capacitor snubber circuit can bottom MOSFET is turned on until the output is cleared. be carefully placed from the switching node pin to ground Pulling the RUN pin below 1.1V forces the regulator into a to dampen any high frequency ringing on the transition shutdown state. The TRACK/SS pin is used for program- edges. See the Applications Information section for details. ming the output voltage ramp and voltage tracking during start-up. See the Application Information section. 4649fc 10 For more information www.linear.com/LTM4649 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Package Photo Revision History Typical Application Design Resources Related Parts