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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Power Supply Controllers, Monitors

STMicroelectronics L6740LTR

Name: L6740LTR
Brand: STMicroelectronics
SKU: L6740LTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L6740LTR

Manufacturer:: STMicroelectronics

Category:: Power Supply Controllers, Monitors

Package:: 48-TQFP Exposed Pad

Datasheet:: L6740LTR.pdf

Description:: IC HYBRID CONTROLLERS 48TQFP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L6740LTR from STMicroelectronics is a hybrid 4+1-phase CPU power supply controller for AMD SVID and PVID processors, integrating independent dual-loop control for CPU CORE (2–4 phases) and NB (1 phase), with 150 kHz fixed/adjustable oscillator, PSI_L-driven light-load efficiency optimization, and dual over-current protection (average + per-phase). It supports desktop/server VRM/VRD designs requiring precise voltage positioning and remote sensing.

For engineers reviewing the L6740LTR datasheet, L6740LTR pinout, L6740LTR application, or L6740LTR equivalent, key selection criteria include SVI/PVI protocol compatibility, HTQFP48 thermal performance, dual-plane voltage positioning, LTB Technology™ transient response enhancement, and programmable OVP/PSI_L timing coordination.

Technical Context

The L6740LTR implements a dual-edge asynchronous architecture with LTB Technology™ to minimize output capacitance and improve load-transient response. Its dual control loops operate independently: one for CORE (supporting 2–4 scalable phases via PWM1–PWM4) and one for NB (NB_PWM), each with dedicated current sensing (CS1+/- through CS4+/- and NB_ISEN), error amplifiers (COMP/NB_COMP), and remote sense inputs (VSEN/NB_VSEN, FBG/NB_FBG).

It decodes VID commands in both PVI (parallel DAC-based) and SVI (serial bus) modes, with automatic mode detection via VID1 edge on EN assertion. PSI_L enables phase shedding during low-power states, while OC_AVG/LI provides CORE-section average over-current latching and load-indicator scaling, and OC_PHASE sets per-phase threshold via ROC_TH.

Key Specifications

Parameter	Value and Actual Design Meaning
Oscillator Frequency	Internally fixed at 150 kHz; externally adjustable via ROSC resistor (6.8 kHz/µA gain) for fine-tuning switching speed.
CORE Phases	Scalable 2–4 phases (PWM1–PWM4); supports 4+1, 3+1, or 2+1 topologies for flexible high-current CPU rail design.
Output Voltage Interface	Hybrid support for AMD PVI (VID0–VID5) and SVI (SVD/SVC/PWROK) protocols with automatic mode detection.
Over-Current Protection	Dual-level: average OC (OC_AVG/LI pin, 2.5 V threshold) and per-phase OC (OC_PHASE pin, 1.24 V reference).
Voltage Positioning	Programmable droop via DROOP/NB_DROOP pins; offset adjustable via OS/NB_OS (1.24 V internal reference) with external ROS resistors.
Remote Sensing	Dual independent remote sense: CORE (VSEN/FBG) and NB (NB_VSEN/NB_FBG), enabling accurate load-point regulation.
PSI Management	PSI_L open-drain I/O enables coordinated phase shutdown during CPU low-power states to boost light-load efficiency.

Pinout & Package

Package: HTQFP48 (7 mm × 7 mm, 0.5 mm pitch), thermally enhanced with exposed pad for improved power dissipation in high-current VRM applications.

Pin/Terminal	Circuit Role	Design Meaning
VCC (Pin 1)	Device power supply	12 V ±15% input; requires 1 µF MLCC to SGND for stable core biasing.
SGND (Pin 2)	Signal ground reference	Common reference for all internal analog blocks; must connect to PCB signal ground plane.
COMP / NB_COMP (Pins 3 / 34)	Error amplifier output	Drives compensation network (RF-CF) for CORE/NB loop stability; not disableable by grounding.
FB / NB_FB (Pins 4 / 33)	Error amplifier inverting input	Connects to VSEN/NB_VSEN via RFB; sinks offset current programmed by OS/NB_OS for voltage positioning.
VSEN / NB_VSEN (Pins 6 / 31)	Output voltage monitor	Direct connection to positive load terminal enables OVP/UVP protection and PWRGOOD generation.
FBG / NB_FBG (Pins 7 / 30)	Remote ground sense	Connects to negative load terminal to cancel PCB IR drop and ensure accurate regulation at point-of-load.
PWM1–PWM4 / NB_PWM (Pins 48,47,46,45 / 44)	Gate drive outputs	Drive external high-side MOSFETs; support interleaved operation for ripple cancellation and thermal spreading.
CS1+–CS4+ / NB_ISEN (Pins 13,15,17,19 / 23)	Current sense positive inputs	Connect to phase inductor high-side for accurate per-phase current measurement and balancing.

Key Features

Feature	Design Value
LTB Technology™ transient response	RLTB–CLTB network detects load steps on CORE rail to accelerate PWM duty-cycle adjustment, reducing required bulk capacitance.
Dual-plane voltage positioning	Independent DROOP and NB_DROOP pins enable programmable load-line slope for CORE and NB rails to meet AMD VRM/VRD specifications.
Pre-biased startup (LS-Less)	Enables safe start-up into pre-charged output without reverse current flow, critical for hot-swap and multi-rail sequencing.
Feedback disconnection protection	Monitors FB/FBG and NB_FB/NB_FBG continuity; disables outputs if sense lines disconnect to prevent unregulated overvoltage.
Flexible driver interface	DRV-compatible gate outputs support discrete or integrated drivers (e.g., L6741/L6743), enabling scalable power stage design.

Applications

Desktop CPU VRM

Server NB Power Delivery

Use Scenario: High-density ATX motherboard powering AMD AM2/AM2+ CPUs with dynamic VID scaling.

IC Role / Device Role / Timing Role: Primary hybrid controller managing 4-phase CORE and 1-phase NB rails, coordinating PWROK handshake and PSI_L state transitions.

Use Value: Enables compliance with AMD VRM 11.x specifications including voltage positioning, phase shedding, and fast transient response under 20 A load steps.

Use Scenario: Dual-rail server motherboard delivering tightly regulated voltage to integrated northbridge logic.

IC Role / Device Role / Timing Role: Dedicated NB controller section (NB_PWM, NB_ISEN, NB_VSEN) operates synchronously with CORE but uses independent compensation and protection.

Use Value: Maintains NB rail stability during CPU frequency scaling events, preventing timing violations in memory controller and PCIe root complex.

Workstation VRD Design

Industrial IPC Power System

Use Scenario: High-reliability workstation platform supporting multi-core Opteron processors with extended temperature operation.

IC Role / Device Role / Timing Role: Hybrid controller executing SVI protocol for dynamic voltage/frequency scaling while maintaining dual remote sensing integrity.

Use Value: Achieves <±0.5% output accuracy across –40°C to +85°C via dual remote sense and programmable offset calibration.

Use Scenario: Fanless industrial PC requiring silent, thermally robust CPU power with long-term supply continuity.

IC Role / Device Role / Timing Role: Core power manager implementing PSI_L–driven phase shedding and LTB-enhanced transient immunity against EMI-induced load spikes.

Use Value: Reduces system power consumption by >35% at 10% load while sustaining <100 µs recovery from 80% load step via LTB Technology™.

Equivalent & Alternatives

The following parts are listed as comparable options for similar hybrid CPU controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ISL6322IRZ	Intel IMVP-6 compliant; single-plane focus (CORE only); no native NB section or SVI support.	Designed for Intel Core 2 platforms; lacks AMD-specific SVI decoding, NB_PWM, and NB_ISEN functionality.	Select only for Intel-based designs requiring IMVP-6 compliance and simpler 1-rail topology.
RT8859AZSP	Single-controller dual-output (CORE+NB); supports AMD SVI2 but no PVI mode; integrated MOSFET drivers.	Targeted at modern AM4 platforms; lacks LTB Technology™ and separate OC_AVG/LI reporting capability.	Choose when upgrading to SVI2 and requiring driver integration, but not for legacy PVI or LTB-critical transient performance.

Compared with ISL6322IRZ and RT8859AZSP, the L6740LTR uniquely delivers dual-mode (PVI/SVI) protocol flexibility, dedicated NB control with full sensing/protection, and LTB Technology™ for superior transient response-making it irreplaceable in legacy AMD desktop/server VRM/VRD designs requiring backward compatibility and thermal headroom.

Availability

L6740LTR is available at Aetrix Electronics and suitable for desktop motherboard VRM, server NB power delivery, and industrial IPC CPU power systems requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for L6740LTR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader specializing in power management, microcontrollers, and analog ICs, with broad industrial and computing portfolio coverage.

The L6740LTR belongs to ST's CPU power controller product line, engineered specifically for AMD processor platforms requiring hybrid PVI/SVI interface support, dual-rail voltage positioning, and high-efficiency multi-phase regulation.

FAQ

What is the function of the LTB and LTB_GAIN pins?

The LTB pin connects to the CORE output rail via an RLTB–CLTB network to detect rapid load transients; the LTB_GAIN pin sets gain via RLTBGAIN resistor to scale LTB response sensitivity. Together they enable LTB Technology™, which accelerates PWM duty-cycle adjustment before traditional error amplifier feedback reacts-reducing output voltage deviation during fast load steps by up to 40%.

How does the L6740LTR handle pre-biased output conditions during startup?

The L6740LTR implements LS-Less startup: it monitors VSEN at power-on and delays gate drive activation until the output reaches a safe threshold, preventing reverse current flow into a pre-charged rail. This avoids stress on external MOSFETs and eliminates need for external anti-backflow circuitry-critical for hot-swap and multi-rail sequencing in server platforms.

Can the L6740LTR operate in single-plane mode only?

Yes-the L6740LTR supports single-plane operation addressing only the CORE section using parallel DAC codification (PVI mode), disabling NB control entirely. In this configuration, NB_PWM, NB_ISEN, and NB-related pins (NB_VSEN, NB_FB, etc.) are unused, and the device functions as a 2–4 phase VRM controller compliant with legacy AMD PVI specifications.

What protections are implemented for feedback line disconnection?

The L6740LTR continuously monitors continuity between FB–FBG and NB_FB–NB_FBG pairs. If either pair opens, the device immediately disables all PWM outputs and asserts FLT on OSC/FLT pin (pulled high to 3.3 V). Recovery requires cycling VCC or EN-preventing unregulated overvoltage that could damage CPU or NB silicon due to loss of closed-loop control.

L6740LTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 48-TQFP Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

Applications:: Hybrid Controllers

Voltage - Input:: -

Voltage - Supply:: 9V ~ 15V

Current - Supply:: 20 mA

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 48-TQFP-EP (7x7)

L6740LTR FAQ

1.How can I place an order for L6740LTR through Aetrix?

Please submit a Request for Quotation (RFQ) for L6740LTR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for L6740LTR reliable?

The price and inventory of L6740LTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6740LTR is usually 5 days.

3.What payment methods are accepted for L6740LTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6740LTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L6740LTR?

L6740LTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L6740LTR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for L6740LTR?

For technical support, including L6740LTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6740LTR requirements.

6.How does Aetrix verify that L6740LTR is sourced from the original manufacturer or authorized distributors?

All L6740LTR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that L6740LTR meets industry standards.

7.What is the process for return or replacement of L6740LTR?

All L6740LTR units undergo pre-shipment inspection (PSI). If there is an issue with L6740LTR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The L6740LTR part is unused and in its original packaging.

Return procedure for L6740LTR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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