L6722TR STMicroelectronics

L6722 3 Phase controller for DC/DC converters Features 2A integrated gate drivers 0.8V reference 1% output voltage accuracy Adjustable reference offset VFQFPN36 Precise current sharing and OCP across LS MOSFETS Constant over current protection Description Feedback disconnection L6722 implements a three-phase step-down LSLESS allows managing pre-bias startup controller with 120 phase-shift between each phase with integrated high-current drivers in a Preliminary of protection compact VFQFPN36 package with exposed pad. Oscillator internally fixed at 100kHz, externally L6722 manages output voltages down to 0.8V adjustable with 1% output voltage accuracy over line and Power good temperature variations. Additional programmable Integrated remote sense buffer offset can be added to the reference voltage with a single external resistor in order to perform VFQFPN36 package with exposed pad margining tests. Applications The controller assures fast protection against load over current and over / under voltage. In case of Memory supply for server and workstation MBs over-current the system works in Constant High density DC / DC converters Current mode until UVP. Preliminary OVP allows full load protection in case of startup with failed High current pol HS. Feedback-disconnection protection prevents from damaging the load in case of misconnections in the remote sense. Pre-bias start-up is also managed thanks to LSLESS. Combined use of DCR and RdsON current sensing assures precision in voltage positioning (by reading droop current across inductors DCR) and safe current sharing and OCP per each phase (by reading the current across LS RdsON). Droop function can be anyway disabled to perform precise and load-insensitive regulation. Order codes Part number Package Packing L6722 VFQFPN36 Tube L6722TR VFQFPN36 Tape & Reel May 2006 Rev 1 1/34 www.st.com 34 Obsolete Product(s) - Obsolete Product(s) Obsolete Product(s) - Obsolete Product(s) L6722 Contents 1 Typical application circuit and block diagram 4 1.1 Application circuit 4 1.2 Block diagram . 6 2 Pins description and connection diagrams 7 2.1 Pin description 7 2.2 Thermal data . 10 3 Electrical specifications . 11 3.1 Absolute maximum ratings 11 3.2 Electrical characteristics 11 4 Device description 13 5 Driver section 14 5.1 Power dissipation . 14 6 Current sharing loop and current reading 16 7 Output voltage positioning . 17 7.1 Offset and margining-mode (optional) . 17 7.2 Droop function (optional) 18 7.3 Maximum duty cycle limitation . 20 8 Soft start 21 8.1 Low-side-less startup for pre-bias output . 21 9 Output voltage monitor and protections 22 9.1 Under voltage 22 9.2 Over voltage . 22 9.3 Preliminary over voltage 22 9.4 Feedback disconnection 23 9.5 PGOOD . 24 2/34 Obsolete Product(s) - Obsolete Product(s) Obsolete Product(s) - Obsolete Product(s)