STMicroelectronics ST1S40IPUR

Overview

ST1S40IPUR from STMicroelectronics is a 3 A synchronous step-down DC-DC regulator with 4.0–18 V input range, adjustable 0.8 V output, 850 kHz fixed-frequency PWM control, and integrated 95 mΩ high-side and 69 mΩ low-side MOSFETs. It delivers high efficiency for low-voltage core supplies in FPGA/ASIC systems.

For engineers reviewing the ST1S40IPUR datasheet, ST1S40IPUR pinout, ST1S40IPUR application, or ST1S40IPUR equivalent, key selection criteria include peak current mode stability, internal soft-start timing (1 ms), thermal shutdown at 150 °C, and compatibility with all-ceramic capacitor designs.

Technical Context

The ST1S40IPUR implements peak current mode control with an internal transconductance error amplifier (Gm = 251 µA/V, Ro = 240 MΩ) and embedded compensation (RC = 70 kΩ, CC = 195 pF), enabling stable loop operation without external components across 4–18 V input and 0.8–VIN output ranges.

It integrates cycle-by-cycle overcurrent protection with dual thresholds (OCP1 ≈ 4–6 A, OCP2 ≈ OCP1 + 1 A), current foldback to ~2 A under severe overload, and hysteretic thermal shutdown (150 °C trip, 130 °C recovery), ensuring robust fault handling in point-of-load applications.

Key Specifications

Pinout & Package

ST1S40IPUR is housed in a VFQFPN 4 mm × 4 mm, 8-lead package with exposed thermal pad (ePad), optimized for high-power density and thermal performance in space-constrained applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Compared with TPS54332DR and MP2315DJ-LF-Z, ST1S40IPUR offers superior integration (dual MOSFETs + compensation + soft-start), tighter output voltage tolerance (±2% vs. ±3%), and lower thermal resistance (40 °C/W vs. ≥55 °C/W), making it optimal for compact, thermally constrained PoL designs.

Availability

ST1S40IPUR is available at Aetrix Electronics and suitable for FPGA core supplies, ASIC I/O rails, and set-top box SoC power delivery requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for ST1S40IPUR 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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The ST1S40 belongs to ST's high-efficiency monolithic DC-DC converter product line, designed specifically for space-constrained, high-current point-of-load applications in computing and multimedia equipment.

FAQ

What is the minimum output voltage achievable with ST1S40IPUR?

The ST1S40IPUR regulates down to 0.8 V ±2% as set by its internal reference. This is the absolute minimum; lower voltages are not supported due to architecture limitations and reference accuracy constraints. External resistor dividers can scale higher outputs, but cannot extend below 0.8 V.

Does ST1S40IPUR require external compensation components?

No. ST1S40IPUR embeds a complete internal compensation network (70 kΩ resistor and 195 pF capacitor) optimized for stability across its full operating range. No external compensation parts are needed, reducing design time and PCB area versus controllers requiring external Type II or III networks.

Can ST1S40IPUR operate with 100% duty cycle?

Yes. The datasheet specifies D_MAX = 100%, enabling dropout operation where V_OUT approaches V_IN. This is critical for applications like 5 V-to-4.5 V post-regulation or maintaining output during brown-out conditions without losing regulation.

What is the recommended PCB layout practice for the ePad on ST1S40IPUR?

The exposed thermal pad must be soldered to a solid copper ground plane using ≥9 thermal vias (0.3 mm diameter, spaced ≤1 mm apart) connecting to inner/ground layers. Avoid splitting the pad or routing signals underneath it - this ensures R_thJA ≤40 °C/W and prevents thermal shutdown under 3 A continuous load.