LM2645MTDX ,Advanced Two-Phase Switching Controller With Two Linear OutputsPin Descriptionsis pulled LOW (<0.8V), and are enabled when this pin ispulled HIGH (>2V).VO1 (Pin 1 ..
LM2647LQ ,Dual Synchronous Buck Regulator ControllerPin Descriptionthe output of the error amplifier of this channel. The voltage(All pin numbers refer ..
LM2647LQ/NOPB ,Dual Synchronous Buck Regulator Controller 28-WQFN -5 to 125Electrical Characteristics table)SS_DCHGbetween this pin and ground to discharge any remaining char ..
LM2647MTC ,Dual Synchronous Buck Regulator ControllerElectrical Characteristics table) between this pin and groundage on the Feedback pin with appropria ..
LM2647MTC ,Dual Synchronous Buck Regulator Controllerfeatures include Soft-start,n Low Output Voltage High-Efficiency Buck RegulatorsPowerGood,outputUnd ..
LM2647MTCX ,Dual Synchronous Buck Regulator Controllerfeaturesn High current N-channel FET driversline feedforward to improve the response to input trans ..
LM4923LQ/NOPB ,1.1 Watt Fully Differential Audio Power Amplifier With Shutdown Select 8-WQFN -40 to 85features an internal thermal shutdown protectionKEY SPECIFICATIONSmechanism.• Improved PSRR at 217H ..
LM4923LQX ,1.1 Watt Fully Differential Audio Power Amplifier With Shutdown Selectfeatures an internal thermaln No output coupling capacitors, snubber networks orshutdown protection ..
LM4924MM ,2 Cell Battery, 40mW Per Channel Output Capacitor-Less (OCL) Stereo Headphone Audio Amplifierfeaturescircuitrythatreducesoutputtransientsn 2-cell 1.5V to 3.6V battery operation(“clicks” and “p ..
LM4924SD ,2 Cell Battery, 40mW Per Channel Output Capacitor-Less (OCL) Stereo Headphone Audio AmplifierGeneral Description Key Specificationsn OCL output powerThe LM4924 is a Output Capacitor-Less (OCL) ..
LM49250RLX/NOPB ,Enhanced Emissions Suppression Stereo Class D Audio Sub-System w/ Ground Referenced Headphone Amp 36-DSBGA -40 to 85Output short circuit and thermal overload protection Connection Diagramprevent the device from bein ..
LM4925SD ,2 Cell, Single Ended Output, 40mW Stereo Headphone Audio AmplifierGeneral Description Key Specificationsn Mono-BTL Output PowerThe unity gain stable LM4925 is both a ..
LM2645MTD-LM2645MTDX
Advanced Two-Phase Switching Controller With Two Linear Outputs
LM2645
Advanced Two-Phase Switching Controller With Two
Linear Outputs
General DescriptionThe LM2645isa feature-richIC that combines two current
mode synchronous buck regulator controllers,an adjustable
linear regulator controller anda fixed 3.3V standby output
rail.
The two switching regulator controllers operate 180˚ outof
phase. This feature reduces the input ripple RMS current,
thereby significantly reducingthe required input capacitance.
The two switching regulator outputs can alsobe paralleledto
operateasa dual-phase regulator.
The useof synchronous rectification and pulse-skip opera-
tionat light load achieves high efficiency overa wide load
range. Fixed-frequency operation canbe obtainedby dis-
abling the pulse-skip mode. The switching frequencyof the
LM2645is user selectable between 200 kHzor 300 kHz.
The first switching controller (Channel1) featuresa fixed5V
output, andthe second switching controller controller (Chan-
nel2) featuresa fixed 3.3V output. Both channels can also independently adjusted from 1.3to 5.5V. The adjustable
linear regulator canbe adjusted from 3.3Vto 15V.An internal railis also available externallyfor driving bootstrap cir-
cuitry. Thisrail also servesasthe inputforan internal LDO
that provides the fixed 3.3V/50mA output rail.
Current-mode feedback control assures excellent line and
load regulation anda wide loop bandwidth for excellent
responseto fast load transients. Currentis sensed across
either the Vdsof the top FETor acrossan external sense
resistor connectedin series with the drainof the top FET.
Current limitis independently adjustablefor each channel.
The analog soft-startfor the switching controllers usesan
innovative new approach.Itis independentof the input
voltage which makes the soft-start behavior more predict-
able and controllable.
Independant PGOOD signals monitor eachofthe switching
regulator outputs. The switching outputs have under-voltage
and over-voltage latch protection, while the outputof the
external linear regulator has undervoltage latch protection.
The undervoltage latch canbe disabledor adjustably de-
layed.
Features
GENERAL 4.5Vto 30V input range Power good function Input under-voltage lockout10μA Shutdown/Recyclefor entire chip Thermal shutdown TSSOP package
SWITCHING SECTION Two synchronous buck regulatorsfor fixed 5V/3.3Vor
adjustable outputs Outputs adjustable from 1.3Vto 5.5V 0.04% (typical) line and load regulation error Selectable switching frequency 200/300 kHz Two channels operating 180˚ outof phase Separate on/offfor each channel Separate Power Good signals Current mode control withor without sense resistor Adjustable cycle-by-cycle current limit Skip-mode operation available Negative current limit Separate soft startfor each channel Output UVP and OVP Programmable output UVP delay Self dischargeof output capacitors when turnedoff
LINEAR SECTION Adjustable (3.3Vto 15V) linear regulator with external
PNP pass transistor ±2% initial toleranceofset voltage Output UVPfor adjustable linear regulator Fixed 3.3V/50mA outputrail Fixed5V referencerail
Applications Notebook and sub-notebook computers Embedded computer systems Battery-powered instruments High end gaming systems Set-top boxes WebPAD
April 2001
LM2645
Advanced
wo-Phase
Switching
Controller
ith
Linear
Outputs
