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 ..
LM2637M ,Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator ControllersLM2637 Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller andTwo Line ..
LM2637MX ,Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator ControllersGeneral DescriptionThe LM2637 provides a comprehensive embedded power
LM2638M ,Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator ControllersLM2638 Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller andTwo Line ..
LM2638MX ,Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator ControllersFeaturessupply solution for motherboards hosting high performancen Provides 3 regulated voltages™ ™ ..
LM4903MMX ,1 Watt Audio Power AmplifierFeaturescoupling capacitors or bootstrap capacitors, and therefore isn Available in space-saving MS ..
LM4905 ,1 Watt Audio Power AmplifierElectrical Characteristics V =5V (Notes 1, 2)DDThe following specifications apply for the circuit s ..
LM4905LD ,1 Watt Audio Power AmplifierFeaturesprovide high quality output power with a minimal amount ofexternal components. The LM4905 d ..
LM4905LDX ,1 Watt Audio Power Amplifierfeatures a low-power consumption shutdownn 2.2 - 5.5V operationmode, which is achieved by driving t ..
LM4905LQ ,1 Watt Audio Power Amplifierfeatures an internal ther-bootstrap capacitors requiredmal shutdown protection mechanism.n Unity-ga ..
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LM2636M-LM2636MTC-LM2636MTCX-LM2636MX
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
