Datasheet LT8714 (Analog Devices) - 13

LT8714
OPERATION OPERATION – FOUR QUADRANT OVERVIEW
From the graph and current flow diagrams, we can have Four quadrant operation means that a device can oper- positive output voltage and positive output current, posi- ate as a power source and as a load irrespective of the tive output voltage and negative output current, negative voltage polarity. To illustrate this concept, please refer to output voltage and positive output current, and negative Figures 1 and 2. output voltage and negative output current. Quadrants I and III transfer power from VIN to VOUT. Quadrants II and IOUT IV transfer power from VOUT back to VIN. The maximum positive output voltage of the four quadrant converter is limited to VIN. VOUT IS II I LIMITED LOAD SOURCE TO VIN
OPERATION – LT8714 OVERVIEW
The LT8714 uses a constant-frequency, current mode control scheme to provide excellent line and load regula- V V OUT IN tion for the four quadrant converter. The part’s under- voltage lockout (UVLO) function and soft-start provide a controlled start up sequence. In addition, synchronous III IV SOURCE LOAD switching makes high efficiency and high output current applications possible. Please refer to the Block Diagram and the State Diagram for the following description of the part’s operation. 8714 F01 CAN REGULATE TO 0V WITH CURRENT DRIVE
Figure 1. Four Quadrant Operation Overview
C1 C1 V L1 • L2 • L1 V • L2 • IN –VOUT IN +VOUT IIN +IOUT IIN +IOUT CIN COUT CIN COUT C
a) QUADRANT II b) QUADRANT I
L1 V • C1 L2 IN • L1 –VOUT V • C1 L2 IN • +VOUT IIN –IOUT IIN –IOUT CIN COUT CIN COUT 8714 F02
c) QUADRANT III d) QUADRANT IV Figure 2. Four Quadrant Topology Current Flow
8714f For more information www.linear.com/LT8714 13 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Appendix Typical Applications Package Description Typical Application Related Parts