LM2636 ,5-Bit Programmable Synchronous Buck Regulator ControllerApplicationsany potential shoot-through problem while maintaining highn Motherboard power supply/VR ..
LM2636M ,5-Bit Programmable Synchronous Buck Regulator ControllerGeneral Descriptionother regulators. Dynamic positioning of load voltage, whichThe LM2636 is a high ..
LM2636MTC ,5-Bit Programmable Synchronous Buck Regulator ControllerPin DescriptionsHSGATE (Pin 20): Gate drive for the high-side N-channelLSGATE (Pin 1): Gate drive f ..
LM2636MTCX ,5-Bit Programmable Synchronous Buck Regulator ControllerGeneral Descriptionother regulators. Dynamic positioning of load voltage, whichThe LM2636 is a high ..
LM2636MX ,5-Bit Programmable Synchronous Buck Regulator ControllerPin DescriptionsHSGATE (Pin 20): Gate drive for the high-side N-channelLSGATE (Pin 1): Gate drive f ..
LM2637 ,Motherboard Power Supply Solution with a 5-Bit
Programmable Switching Controller and Two Linear Regulator ControllersElectrical Characteristics= = = =V 5V, V 12V unless otherwise specified. Typicals and limits appear ..
LM4902LD ,265mW at 3.3V Supply Audio Power Amplifier with Shutdown ModeApplicationsKey Specificationsn Cellular phonesj n PDA’sTHD+N at 1kHz for 265mW continuousn Any por ..
LM4902LDX ,265mW at 3.3V Supply Audio Power Amplifier with Shutdown ModeElectrical Characteristics (Note 1) (Note 2)The following specifications apply for V = 5V, for all ..
LM4902MM ,265mW at 3.3V Supply Audio Power Amplifier with Shutdown ModeLM4902 265mW at 3.3V Supply Audio Power Amplifier with Shutdown ModeFebruary 2002LM4902265mW at 3.3 ..
LM4902MM/NOPB ,265mW at 3.3V Supply Audio Power Amplifier with Shutdown Mode 8-VSSOP -40 to 85features an externally controlled, low• Cellular Phonespower consumption shutdown mode, and thermal ..
LM4902MMX ,265mW at 3.3V Supply Audio Power Amplifier with Shutdown Modefeatures an externally controlled, low powern Thermal shutdown protection circuitryconsumption shut ..
LM4902MMX ,265mW at 3.3V Supply Audio Power Amplifier with Shutdown ModeFeaturesage while requiring a minimal amount of external compo-nents. Since the LM4902 does not req ..
LM2636
5-Bit Programmable Synchronous Buck Regulator Controller
LM2636
5-Bit Programmable Synchronous Buck Regulator
Controller
General DescriptionThe LM2636isa high speed controller designed specifically
forusein synchronous DC/DC buck convertersfor advance microprocessors.A 5-bit DAC acceptsthe VID codedi-
rectly fromthe CPUand adjuststhe output voltage from 1.3V 3.5V.It providesthe power good, over-voltage protection,
and output enable featuresas requiredby Intel VRM speci-
fications. Current limitingis achievedby monitoringthe volt-
age drop acrossthe rDS_ONofthe high side MOSFET, which
eliminatesan expensive current sense resistor.
The LM2636 employsa fixed-frequency voltage mode PWM
architecture.To provide afaster responsetoa largeandfast
loadtransient, twoultra-fast comparators arebuiltinto moni-
torthe output voltage and overridethe primary control loop
when necessary.The PWM frequencyis adjustable from50
kHzto 1MHzthrough anexternal resistor.The wide rangeof
PWM frequency gives thepower supply designer theflexibil-
ityto make trade-offs between load transient response per-
formance, MOSFET cost andthe overall efficiency. The
adaptive non-overlapping MOSFET gate drivers help avoid
any potential shoot-through problem while maintaining high
efficiency. BiCMOS gate driverswith rail-to-rail swing ensure
thatno spurious turn-on occur. When only5Vis available,a
bootstrap structurecanbe employedto accommodatean
NMOS high side switch.The precision reference trimmedto
2.5% over temperatureis available externallyfor useby
other regulators. Dynamic positioningof load voltage, which
helpscutthe number ofoutputcapacitors,can alsobe imple-
mented easily.
Features 1.3Vto 3.5V 5-bit programmable output voltage Synchronous rectification Power Goodflagand output enable Over-voltage protection Initial Output Accuracy: 1.5% over temperature Current limit without external sense resistor Adaptive non-overlapping MOSFET gate drives Adjustable switching frequency:50 kHzto1 MHz Dynamic output voltage positioning 1.256V reference voltage available externally Plastic SO-20 packageand TSSOP-20 package
Applications Motherboard power supply/VRMfor Cyrix Gxm, Cyrix
Gxi, CyrixMII, Pentium™II, Pentium Pro, 6x86andK6
processors5Vto 1.3V–3.5V high current power supplies
Typical ApplicationPentium™isatrademark ofIntelCorporation.
DS100834-1
FIGURE1.5Vto 1.3V–3.5V, 14A Power SupplyOctober 1999
LM2636
5-Bit
Programmable
Synchronous
Buck
Regulator
Controller©1999 National Semiconductor Corporation DS100834
