LTC1709-8 - 2-Phase, 5-Bit VID, Current Mode, High Efficiency, Synchronous Step-Down Switching Regulators

The LTC1709-8/LTC1709-9 are 2-phase, VID programmable, synchronous step-down switching regulator controllers that drive two all N-channel external power MOSFET stages in a fixed frequency architecture. The 2-phase controller drives its two output stages out of phase at frequencies from 150kHz to 300kHz to minimize the RMS ripple currents in both input and output capacitors. The 2-phase technique effectively multiplies the fundamental frequency by two, improving transient response while operating each channel at an optimum frequency for efficiency. Thermal design is also simplified.

An internal differential amplifier provides true remote sensing of the regulated supply’s positive and negative output terminals as required for high current applications.

The RUN/SS pin provides soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when the overcurrent latchoff is disabled. OPTI-LOOP compensation allows the transient response to be optimized for a wide range of output capacitors and ESR values. The LTC1709-8/LTC1709-9 implement two different VID tables compliant with VRM8.4 and VRM9.0 respectively.

Features

Single Controller Operates Two Output Stages Antiphase Reducing Required Input Capacitance and Power Supply Induced Noise
Two 5-Bit Desktop VID Codes: LTC1709-8 For VRM8.4 (VOUT from 1.3V to 3.5V) LTC1709-9 For VRM9.0 (VOUT from 1.1V to 1.85V)
Current Mode Control Ensures Best Current Sharing
True Remote Sensing Differential Amplifier
Power Good Output Indicator
OPTI-LOOP™ Compensation Minimizes COUT
Programmable Fixed Frequency: 150kHz to 300kHz
±1% Output Voltage Accuracy
Wide VIN Range: 4V to 36V Operation
Adjustable Soft-Start Current Ramping
Internal Current Foldback and Short-Circuit Shutdown
Overvoltage Soft Latch Eliminates Nuisance Trips
Low Shutdown Current: 20µA
Available in 36-Lead Narrow SSOP Package

Typical Application

Applications

Workstations
Internet Servers
Large Memory Arrays
DC Power Distribution Systems

Packaging

Order Information

Part Number	Package	Temp	Price(1-99)	Price (1k)*
LTC1709EG-8#PBF	SSOP-36	E	$5.60	$4.75
LTC1709EG-8#TRPBF	SSOP-36	E		$4.85

Demo Boards

Part Number	Description	Price
DC292A	LTC1709EG-8 \| High Current Microprocessor Supply, 12Vin, 1.6Vout @ 52A, (10mm X 20mm Thru-hole Sanyo Caps)	Contact Factory
DC292B-B	LTC1709EG-8 \| High Current VRM 8.4 CPU Power Supply, 12Vin, 1.6Vout @ 45A, (mostly Surface Mount Caps)	Contact Factory