Document
OBSOLETE
LM27262
www.ti.com
SNVS262C – MAY 2004 – REVISED SEPTEMBER 2011
LM27262 Intel CPU Core Voltage Regulator Controller for VRD10 Compatible PCs
Check for Samples: LM27262
FEATURES
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•234 Compatible with “VRD10 Voltage Regulation Specification” for Intel Pentium 4 and Prescott Processors
• Supports Intel SpeedStep™ Technology ( Geyserville-III™), which Enables Real-Time Dynamic Switching of the CPU Core Voltage and the CPU Clock Frequency
• Uses External Gate Drivers (LM2724) for Maximum Layout Flexibility and Noise Immunity
• Fixed Frequency PWM Architecture
• Pin Selectable Internal or External Voltage Reference
• 0.5% Core Voltage Set-Point Accuracy when Using External Voltage Reference
• 0.9% Accurate Internal Bandgap Reference
• 2-, 3- or 4-Phase Operation
• Out-of-Phase Switching Reduces Input Ripple Current, Thereby Minimizing Input Capacitor Requirements
• VID-Code Programmable Output Voltage Range of 0.8375V through 1.6000V
• User Programmable, Low Loss, Load Line Slope
• User Programmable Standard VID Offset
• User Programmable VCORE Slew Rate
• 5V Power Rail Under Voltage Lock Out (UVLO)
• Over Voltage Protection (OVP), Under Voltage Protection (UVP), and Over Current Protection (OCP) to Defend Against Potentially Catastrophic Events
• User Programmable Fault Latch That Can Be Used to Disable the Regulator in the Event a Power System Fault
• Very Fast Transient Response
• VID-Transition Masked PWRGOOD Output
• True-Differential Current Sensing for Each Phase Ensures Accurate Load Current Sharing
• User Programmable Cycle-by-Cycle Current Limit
APPLICATIONS
• Server and Desktop Computer CPU Core Power Supplies Requiring a 2, 3- or 4-Phase Voltage Regulator Delivering up to 100A
• Transportable Notebook Computers Using Desktop CPUs
• Low Cost Transportable Notebook Computers Using 2- or 3-Phase Designs
KEY SPECIFICATIONS
• Fast Transient Response to Minimize Output Capacitor Requirements
• Shorter Design Cycles Through the Use of External Gate Drivers for Reduced Power Dissipation, Ease of PCB Layout and Reduced Noise Sensitivity
• Fully Integrated Solution. All VRD-10 Control Functions Provided by a Single Device
• Accurate Current Balancing Eliminates Need to Over Design the Power Path
• Fixed Frequency PWM Minimizes EMI Issues • Low Input Capacitor Requirements Due to
Multi-Phase Interleaving • Fault Latching Allows Use of Smaller Power
Path Components and Minimizes the Chance of Damage to the Load in the Event of a Fault • Only Need to Buy as Many Drivers as the Design Needs while Keeping Only One Controller in Inventory
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Pentium is a trademark of Intel Corporation..
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SpeedStep, Geyserville-III, Prescott are trademarks of dcl_owner.
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All other trademarks are the property of their respective owners.
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PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.
Copyright © 2004–2011, Texas Instruments Incorporated
LM27262
OBSOLETE
SNVS262C – MAY 2004 – REVISED SEPTEMBER 2011
www.ti.com
DESCRIPTION
The LM27262 is a versatile synchronous buck voltage regulator controller designed according to the Intel VRD10 Specification. It’s a fixed-frequency voltage-mode control PWM with average current modulation of the reference voltage to achieve the desired output impedance. This approach imparts a pseudo current mode behavior to the control loop. The part provides the control for a voltage regulator consisting of either 2-, 3- or 4-phases to provide power to a desktop CPU. Pulse-by-pulse phase current balancing ensures accurate current sharing. CPU core currents of over 90A can be supported without requiring significant over design of the power path. The LM27262 contains a precision 6-bit digital-to-analog converter (DAC) that uses a VID-code provided by the CPU to program the desired CPU core voltage. The regulator output voltage can be dynamically adjusted by changing the VID-code “on the fly”.
The part is intended to provide all the specified functions laid out in the VRD-10 specification, making it as simple as possible for the user to realize a fully compliant CPU core supply for Intel’s Pentium™4 and Prescott™ processors.
The LM27262 is available in a 48-lead TSSOP package and in a 48-lead WQFN package.
Typical Application Circuit
+V3.3S
R1
VRE F
6.8k C3
C1 C2
1 PF
1
3 1 PF 0.1 PF
2
CR2 LM27201 Optional External
Reference
C4 0.1 PF
U1
R4
1 PHASE
VRO 48
C7 1000 pF
R2 976_1%
17.4k_1%
2
309_1%
C9 10 nF
3 4
R3 5
R7 6
4.75k_1% 7
VR_VID VR_0VID VR_1VID VR_2VID VR_3VID VR_4VID
.