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™ ™ ..
LM2639M ,5-Bit Programmable, High Frequency Multi-phase PWM ControllerFeatures™ ™ ™MII ,K6 -2, K6 -3, etc.) exhibiting ultra fast load tran-n Ultra fast load transient r ..
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 ..
LM4905MM ,1 Watt Audio Power AmplifierGeneral Description Key SpecificationsThe LM4905 is an audio power amplifier primarily designedj Im ..
LM4906LD ,1W, Bypass-Capacitor-less Audio Power Amplifier with Internal Selectable Gainapplications.n Minimum external componentsThe LM4906 contains advanced pop and click circuitry that ..
LM4906MM ,1W, Bypass-Capacitor-less Audio Power Amplifier with Internal Selectable GainFeaturesPower Amplifier that does not require an external PSRRbypass capacitor. The LM4906 also has ..
LM2637
Motherboard Power Supply Solution with a 5-Bit
Programmable Switching Controller and Two Linear Regulator Controllers
LM2637
Motherboard Power Supply Solution witha 5-Bit
Programmable Switching Controller and Two Linear
Regulator Controllers
General DescriptionThe LM2637 providesa comprehensive embedded power
supply solutionfor motherboards hosting high performance
MPUs suchasM II™, Pentium™II, K6-2 and other similar
high performance MPUs. The LM2637 incorporatesa 5-bit
programmable, synchronous buck switching controller and
two high-speed linear regulator controllersina 24-pinSO
package.
Switching Section— The switching regulator controllerfea-
turesa 5-bit programmable DAC, over-current and
over-voltage protection, under-voltage latch-off,a power
good signal,and output enable.The 5-bit DAChasa typical
toleranceof1%. Therearetwo user-selectable over-current
protection methods. One provides accurateover-currentpro-
tection withtheuseofan external sense resistor.The other
saves costby taking advantageof the rDS_ONof the
high-side FET.The overvoltage protection providestwolev-
elsof protection. Thefirst level keepsthe high-side FEToff
andthe low-side FETon.The second providesa gate signal
thatcanbe usedtofirean external SCR.
Linear Section— Thetwo linear regulator controllers fea-
ture wide control bandwidth, N-FETand NPN transistordriv-
ing capability, andan adjustable output voltage. The wide
control bandwidth makes meeting fast load transientre-
sponse requirement suchasthatofthe GTL+busan easy
job.In minimum configuration,thetwo controllers defaultto
1.5Vand 2.5V respectively.
Both linear controllers have under voltage latch-off.
Features Provides3 regulated voltages Power Goodflagand output enable Under-voltage latch-off
Switching Section Synchronous rectification 5-bit DAC programmable from 3.5Vto 1.3V Typical1% DAC tolerance Switching frequency:50kHzto1 MHz Two levelsof over-voltage protection Two methodsof over-current protection Adaptive non-overlapping FET gate drives Soft start without external capacitor
Linear Section N-FETand NPN driving capability Ultrafast response speed Output voltages defaultto 1.5Vand 2.5Vyet adjustable
Applications Embedded power suppliesforPC motherboards Triple DC/DC power supplies Programmable high current DC/DC power supply
Pin ConfigurationMII™ isatrademarkofCyrix Corporationawholly owned subsidiaryof National Semiconductor Corporation.
Pentium™isatrademark ofIntel Corporation.
K6istrademark ofAdvancedMicro Devices,Inc.
24-Lead SOICDS100848-1
Top View Package Number M24BOctober 1998
LM2637
Motherboard
Power
Supply
Solution
with
5-Bit
Programmable
Switching
Controller
and
Linear
Regulator
Controllers 1999 National Semiconductor Corporation DS100848
