L6756D STMicroelectronics, L6756D Datasheet - Page 19

• Manufacturer Part Number: L6756D
• Description: IC CTLR 2/3/4PH BUCK 40-VFQFPN
• Manufacturer: STMicroelectronics

Specifications of L6756D

• Applications: Controller, Intel VR10, VR11, VR11.1
• Voltage - Input: 12V
• Number Of Outputs: 4
• Voltage - Output: 0.3 ~ 1.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 40-VFQFN, 40-VFQFPN
• Output Voltage: 3 V
• Input Voltage: - 0.3 V to + 15 V
• Switching Frequency: 185 KHz to 215 KHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L6756D
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Device description and operation
L6756D is a programmable two-to-four phase PWM controller providing complete control
logic and protections for a high performance step-down DC-DC voltage regulator optimized
for advanced microprocessor power supply. The device is a dual-edge asynchronous PWM
controller featuring patented LTB Technology
simultaneously all the phases allowing to minimize output voltage deviation so minimizing
the system cost by providing the fastest response to a load transition.
Multi-phase buck is the simplest and most cost-effective topology employable to satisfy the
increasing current demand of newer microprocessors and modern high current VRM
modules. It allows distributing equally load and power between the phases using smaller,
cheaper and most common external power MOSFETs and inductors. Moreover, thanks to
the equal phase shift between each phase, the input and output capacitor count results in
being reduced. Phase interleaving causes in fact input rms current and output ripple voltage
reduction and show an effective output switching frequency increase: the 200 kHz
free-Running frequency per phase, externally adjustable through a resistor, results
multiplied on the output by the number of phases.
L6756D permits easy system design by allowing current reading across inductor in fully
differential mode. Also a sense resistor in series to the inductor can be considered to
improve reading precision. The current information read corrects the PWM output in order to
equalize the average current carried by each phase.
The controller includes multiple DACs, selectable through an apposite pin, allowing
compatibility with Intel VR10, VR11 and VR11.1 processors specifications, also performing
D-VID transitions accordingly.
The device is VR11.1 compatible implementing the Imon signal and managing the PSI#
signal to enhance the system performances at low current in low power-states.
Low-side-less start-up allows soft-start over pre-biased output avoiding dangerous current
return through the main inductors as well as negative spike at the load side.
L6756D provides overvoltage protection to protect the load from dangerous over stress
latching immediately by turning ON the lower driver and driving high the FAULT pin.
The device is available in a compact VFQFPN40 with 6x6 mm body package.
®
: through a load transient detector, it turns on
Device description and operation
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