STMicroelectronics L6911ETR

Overview

L6911ETR from STMicroelectronics is a 5-bit programmable synchronous buck controller for microprocessor core power supplies, featuring voltage-mode PWM control, ±1% output accuracy over line/temperature, 200 kHz–1 MHz adjustable switching frequency, and integrated overvoltage/overcurrent protection with HICCUP mode recovery. It drives external N-channel MOSFETs in a high-efficiency step-down topology delivering 1.050 V to 1.825 V at up to 30 A (system-level) with 25 mV binary steps.

For engineers reviewing the L6911ETR datasheet, L6911ETR pinout, L6911ETR application, or L6911ETR equivalent, this controller is selected for VRM 8.5-compliant CPU core supplies requiring precise VID-programmable regulation, fast transient response (<100 ns load step), gate drive strength up to 1.3 A source/sink, and dual OVP strategies (internal low-side crowbar + external SCR trigger).

Technical Context

This controller implements voltage-mode PWM with a 15 MHz gain-bandwidth error amplifier and 10 V/µs slew rate to support high-loop bandwidth and sub-10 µs load transient recovery. The internal 5-bit DAC sets both output voltage and associated PGOOD/OVP thresholds via TTL-compatible VID0–VID4 pins, eliminating external resistor dividers.

Oscillator frequency is factory-set to 200 kHz and externally adjustable from 50 kHz to 1 MHz using a single RT-to-GND or RT-to-VCC resistor; dead-time control prevents shoot-through, and current limiting uses upper MOSFET R_DS(ON) sensing-no sense resistor required.

Key Specifications

Pinout & Package

TSSOP-20 package (3.5 mm × 8.5 mm, 0.65 mm pitch) with exposed thermal pad for enhanced power dissipation in high-current DC/DC designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with ISL6522CRZ and TPS51116PWR, the L6911ETR offers superior output accuracy (±1% vs. ±1.5%) and component count reduction via R_DS(ON) current sensing, making it optimal for cost-sensitive, thermally constrained VRM 8.5 implementations where 1.3 A gate drive suffices.

Availability

L6911ETR is available at Aetrix Electronics and suitable for desktop CPU core supplies, laptop VRMs, server blade DC/DC modules, and FPGA core voltage regulators requiring stable component supply throughout product lifecycles.

Supply support for L6911ETR 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 headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and automotive ICs with vertical fabrication capabilities.

The L6911ETR belongs to ST's VRM-compliant power controller product line, engineered specifically for high-efficiency, digitally programmable DC/DC conversion in advanced microprocessor core power applications.

FAQ

What is the maximum supported switching frequency for the L6911ETR?

The L6911ETR supports an externally adjustable switching frequency from 50 kHz to 1 MHz using the RT pin. With no external resistor (RT open), the default frequency is 200 kHz ±15%. Frequency increases when RT is connected to GND and decreases when connected to V_CC, per documented equations in the datasheet.

How does the L6911ETR implement overcurrent protection without a sense resistor?

It uses the upper MOSFET's R_DS(ON) as the current-sensing element. A 200 µA internal current source flows from OCSET to the MOSFET drain, generating a voltage drop across R_DS(ON). When this voltage exceeds a threshold, overcurrent is detected - eliminating the need for a discrete sense resistor and associated power loss.

Can the L6911ETR be used with a 5 V input bus?

Yes. The V_CC supply range is 4.5 V to 12 V, fully compatible with 5 V system rails. However, VIN (power stage input) must be ≥1.26 V, and the device regulates output down to 1.050 V. Note: Do not connect VIN to 12 V if V_CC is 5 V, per absolute maximum ratings.

What happens during an overvoltage event on the output?

When VSEN exceeds 117–120% of the programmed output voltage, the OVP pin goes high (capable of sourcing 60 mA) to trigger an external SCR, while the low-side MOSFET is turned on continuously to clamp the output - providing dual-path crowbar protection even if the SCR is omitted.