LM2647 - Dual Synchronous Buck Regulator Controller
Datasheet Packaging Samples & Pricing Eval. Boards Reliability Knowledge Base

Features
•Input voltage range from 5.5V to 28V
•Synchronous dual-channel Interleaved switching
•Forced-PWM or Pulse-skip modes
•Lossless bottom-side FET current sensing
•Adaptive duty cycle clamping
•High current N-channel FET drivers
•Low shutdown supply currents
•Reference voltage accurate to within ±1.5%
•Output voltage adjustable down to 0.6V
•Power Good flag and Chip Enable
•Under-voltage lockout
•Over-voltage/Under-voltage protection
•Soft-start and Soft-shutdown
•Switching frequency adjustable 200kHz-500kHz

General Description

The LM2647 is an adjustable 200-500kHz dual channel voltage-mode controlled high-speed synchronous buck regulator controller ideally suited for battery powered applications such as laptop and notebook computers. More...


Applications

•Notebook Chipset Power Supplies
•Low Output Voltage High-Efficiency Buck Regulators
  Typical Application
click for larger image


ParametersValues
Channels 2 Channels
Topology Buck
Output Current 20000 mA
Input Min Voltage 5.5 Volt
Input Max Voltage 28 Volt
Output Range 0.6V to 5V
Frequency Min 200 kHz
Frequency Max 500 kHz
Feedback Voltage 0.6 Volt
Feedback Tolerance 1.5 %
Adj Switch Frequency Yes
Adjustable Output Yes
Synchronous Rectification Yes
On/Off Pin Yes
Error Flag Yes
SoftStart Yes
Sync Pin No
Inverting No
Flyback No
Lossless Current Sense Yes
RegType Switching Controller
Temperature Min -5 deg C
Temperature Max 125 deg C
Special Features PWM/SKIP and FPWM modes; Soft shutdown; Line feedforward; 180deg out-of-phase
PWM Mode Voltage with Vin Feedforward
Step-Down Yes
Step-Up No
Output Max 5 Volt
Output Min 0.6 Volt


Typical Performance

click for larger image


  Block Diagram
click for larger image



Datasheet
RoHS Compliance Information Size in KbytesDate Click link below to Download
LM2647 Dual Synchronous Buck Regulator Controller 1726
Kbytes		 29-Jun-05 Download

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Package Availability, Models, Samples & Pricing
Part NumberPackageFactory Lead TimeModelsSamples &
Electronic
Orders		Budgetary PricingStd
Pack
Size		Package
Marking
Format
TypePinsSpec.MSL
Rating		Peak
Reflow		RoHS
Report		CAD
Symbols		WeeksQtyQty$US each
LM2647EVALDual Synchronous Buck Regulator ControllerFull productionN/A
 
Buy Now 		1+$153.001-
8 weeksN/A
LM2647LQLLP28NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$1.90reel
of
1000		NS
UZXYTTE#
LM2647
6 weeks5000
LM2647LQXLLP28NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$1.90reel
of
4500		NS
UZXYTTE#
LM2647
6 weeksN/A
LM2647MTCTSSOP28NOPB3260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$1.90rail
of
48		NSUZXYTTE#
LM2647
MTC
6 weeks500
LM2647MTCXTSSOP28NOPB
STD		3
3		260
235		RoHS Download Full productionN/A
 
Buy Now 		1K+$1.90reel
of
2500		NSUZXYTTE#
LM2647
MTC
6 weeks10000

General Description

The LM2647 is an adjustable 200-500kHz dual channel voltage-mode controlled high-speed synchronous buck regulator controller ideally suited for battery powered applications such as laptop and notebook computers. The LM2647 requires only N-channel FETs for both the upper and lower positions of each synchronous stage. It features line feedforward to improve the response to input transients. At very light loads, the user can choose between the high-efficiency Pulse-skip mode or the constant frequency Forced-PWM mode. Lossless current limiting without the use of external sense resistors is made possible by sensing the voltage drop across the bottom FET. A unique adaptive duty cycle clamping technique is incorporated to significantly reduce peak currents under abnormal load conditions. The two independently programmable outputs switch 180° out of phase (interleaved switching) to reduce the input capacitor and filter requirements. The input voltage range is 5.5V to 28V while the output voltages are adjustable down to 0.6V.

Standard supervisory and control features include Soft-start, Power Good, output Under-voltage and Over-voltage protection, Under-voltage Lockout, Soft-shutdown and Enable.

Reliability Metrics

Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM2647LQABCD15003417500423400011201409060
LM2647LQXABCD15003417500423400011201409060
LM2647MTCABCD15003417500423400011201409060
LM2647MTCXABCD15003417500423400011201409060

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.


[Information as of 7-Nov-2009]