Features: . Wide VIN Range: 4V to 32V
. ±0.67% 0.6V Reference Voltage
. Output Voltage Tracking Capability
. Programmable Margining
. Sense Resistor Optional
. True Current Mode Control
. 2% to 90% Duty Cycle at 200kHz
. tON(MIN) 100ns
. Phase Lock Loop Frequency Synchronization
. Powerful Dual N-Channel MOSFET Driver
. Adjustable Cycle-by-Cycle Current Limit
. Adjustable Switching Frequency
. Programmable Soft-Start
. Current Foldback Protection (Disabled at Start-Up)
. Output Overvoltage Protection
. Micropower Shutdown: IQ < 30µA
. Power Good Output Voltage Monitor
Tracks the Reference Input Pin
. Available in (5mm* 5mm) QFN and 28-Lead
SSOP PackagesApplicationDistributed Power Systems
Server Power SupplyPinout
SpecificationsInput Supply Voltage (VIN, VINSNS)............32V to 0.3V
Boosted Topside Driver Supply Voltage
(BOOST).......................................................38V to 0.3V
SENSE+, SW Voltage.......................................32V to 5V
DRVCC, (BOOST SW) Voltages.....................7V to 0.3V
VON, VRNG, PGOOD Voltages......INTVCC + 0.3V to 0.3V
PLLFLTR, ITH, VFB, VREFIN Voltages............2.7V to 0.3V
TRACK/SS, FCB, Z0, Z1, Z2, RUN, PLLIN, MARGIN0,
MARGIN1 Voltages.......................INTVCC + 0.3V to 0.3V
INTVCC, ZVIN Voltages...................................7V to 0.3V
TG, BG, INTVCC Peak Currents......................................4A
TG, BG, INTVCC RMS Currents...................................50mA
Operating Ambient Temperature
Range (Note 4)............................................40°Cto 85°C
Junction Temperature (Note 2)................................125°C
Storage Temperature Range.....................65°Cto 125°C
QFN Reflow Peak Body Temperature.......................245°C
Lead Temperature (Soldering, 10 sec)....................300°C
DescriptionThe LTC®3770 is a synchronous step-down switchingregulator controller with output voltage up/down trackingcapability and voltage margining. Its advanced functionsand high accuracy reference are ideal for poweringhigh performance server, ASIC and computer memorysystems.
The LTC3770 uses a constant on-time, valley currentmode control architecture to deliver very low duty factorswithout requiring a sense resistor. The operating fre-quency is selected by an external resistor and is compen-sated for variations in input supply voltage. An internalphase-lock loop allows the IC to be synchronized to anexternal clock.
Fault protection of LTC3770 is provided by an overvoltage comparatorand input undervoltage lockout. The regulator current limitis user programmable. A wide supply range allows volt-ages as high as 32V to be stepped down to as low as a 0.6Voutput. Power supply sequencing is accomplished usingan external soft-start timing capacitor.
LTC3770 Data Sheet
