LX1668CDW

LX1668CDW Datasheet

LX1668

Part	Datasheet
LX1668CDW	LX1668CDW (pdf)

Related Parts	Information
LX1668CPW	LX1668CPW

PDF Datasheet Preview
L I N D O C # 1668 LX1668 P ROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER PR O D U C T I O N DATASHEET The LX1668 is a Monolithic Switching Regulator Controller IC designed to provide a low cost, high performance adjustable power supply for advanced microprocessors and other applications requiring a very fast transient response and a high degree of accuracy. It provides a programmable switching regulator output, together with one internal linear low dropout regulator and one adjustable linear regulator driver. The LX1668 offers a triple-output single-chip power supply for II and other processors. Programmable Synchronous Rectifier Driver for CPU Core. The main output is adjustable from to 3.5V using a TTLcompatible 5-bit digital code to meet Intel specifications. The IC can read the signal from a DIP-switch, hardwired to Pentium II processor’s pins or from software. The 5-bit code adjusts the output voltage between and 2.05V in 50mV increments, and between and 3.5V in 100mV increments. The device can drive dual MOSFET’s resulting in typical efficiencies of 85 90%, even with loads in excess of 10A. Internal Low Dropout [LDO] Regulator provides a fixed 2.5V output for powering the clock circuit at up to 250mA. External Linear Regulator Driver output can be connected to a MOSFET to provide a high-current adjustable LDO function suitable for supplying the GTL+ bus circuitry on a Pentium II processor motherboard at 1.5V. Short-circuit Current Limiting without Expensive Current Sense Resistors. The current sensing mechanism can use a PCB trace resistance or the parasitic resistance of the main inductor. For applications requiring a high degree of accuracy, a conventional sense resistor can be used. Ultra-Fast Transient Response Reduces System Cost. The fixed frequency modulated off-time architecture results in the fastest transient response for a given inductor. Small Package Size. The LX1668 is available in an economical 20-pin wide body SOIC or a space-saving 20-pin TSSOP package. NOTE For current data & package dimensions, visit our web site: KEY FEATURES s 5-Bit Programmable Output For CPU Core Supply s Internal Fixed 2.5V Low Dropout Regulator s Adjustable Linear Regulator Driver s Complete Single-Chip Power Solution For Pentium II Processors s No Sense Resistor Required For Short-Circuit Current Limiting s Soft-Start And Hiccup-Mode Current Limiting Functions s Modulated Constant Off-Time Control Mechanism For Fast Transient Response And Simple System Design s Power Good Flag s Over-Voltage Pin & SCR s Digital-Compatible Inputs Including VID Pins s Output Disable Function Shuts Off PWM While Keeping 2.5V LDO Active - Compatible With "Green PC" And "Instant On" Requirements s Compatible to VRM8.2 - Specifications A P L I C AT I O N S s Pentium II & Pentium III Processor Supplies s Voltage Regulator Modules s General Purpose And Microprocessor DC:DC Supplies PRODUCT HIGHLIGHT 5V 12V 1µF 1µF VOUT2 2.5V C5 22µF 1µF 3.3V VOUT3 1.5V C4 330µF C6 330µF IRLZ44 R1, 0 R2, 50k L2 1µH C7 1µF 1 TDRV PGND 20 2 VCC12 BDRV 19

PDF Datasheet Preview

L I N D O C # 1668

LX1668

P ROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER PR O D U C T I O N DATASHEET

The LX1668 is a Monolithic Switching Regulator Controller IC designed to provide a low cost, high performance adjustable power supply for advanced microprocessors and other applications requiring a very fast transient response and a high degree of accuracy. It provides a programmable switching regulator output, together with one internal linear low dropout regulator and one adjustable linear regulator driver. The LX1668 offers a triple-output single-chip power supply for II and other processors.

Programmable Synchronous Rectifier Driver for CPU Core. The main output is adjustable from to 3.5V using a TTLcompatible 5-bit digital code to meet Intel specifications. The IC can read the signal from a DIP-switch, hardwired to Pentium II processor’s pins or from software. The 5-bit code adjusts the output voltage between and 2.05V in 50mV increments, and between and 3.5V in 100mV increments. The device can drive dual MOSFET’s resulting in typical efficiencies of 85 90%, even with loads in excess of 10A.

Internal Low Dropout [LDO] Regulator provides a fixed 2.5V output for powering the clock circuit at up to 250mA.

External Linear Regulator Driver output can be connected to a MOSFET to provide a high-current adjustable LDO function suitable for supplying the GTL+ bus circuitry on a Pentium II processor motherboard at 1.5V.

Short-circuit Current Limiting without Expensive Current Sense Resistors. The current sensing mechanism can use a PCB trace resistance or the parasitic resistance of the main inductor. For applications requiring a high degree of accuracy, a conventional sense resistor can be used.

Ultra-Fast Transient Response Reduces System Cost. The fixed frequency modulated off-time architecture results in the fastest transient response for a given inductor. Small Package Size. The LX1668 is available in an economical 20-pin wide body SOIC or a space-saving 20-pin TSSOP package.

NOTE For current data & package dimensions, visit our web site:

KEY FEATURES
s 5-Bit Programmable Output For CPU Core Supply
s Internal Fixed 2.5V Low Dropout Regulator s Adjustable Linear Regulator Driver s Complete Single-Chip Power Solution For

Pentium II Processors s No Sense Resistor Required For Short-Circuit

Current Limiting s Soft-Start And Hiccup-Mode Current Limiting

Functions s Modulated Constant Off-Time Control

Mechanism For Fast Transient Response And Simple System Design s Power Good Flag s Over-Voltage Pin & SCR s Digital-Compatible Inputs Including VID Pins s Output Disable Function Shuts Off PWM While Keeping 2.5V LDO Active - Compatible With "Green PC" And "Instant On" Requirements s Compatible to VRM8.2 - Specifications

A P L I C AT I O N S
s Pentium II & Pentium III Processor Supplies s Voltage Regulator Modules s General Purpose And Microprocessor DC:DC

Supplies

PRODUCT HIGHLIGHT
5V 12V
1µF
1µF

VOUT2
2.5V C5
22µF
1µF
3.3V

VOUT3 1.5V

C4 330µF

C6 330µF

IRLZ44

R1, 0

R2, 50k

L2 1µH

C7 1µF
1 TDRV

PGND 20
2 VCC12

BDRV 19

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Datasheet ID: LX1668CDW 648553