STMicroelectronics ST1S41PHR

Overview

ST1S41PHR from STMicroelectronics is a synchronous step-down switching regulator IC delivering up to 4 A output current, operating from 4.0 V to 18 V input, with adjustable output down to 0.8 V and fixed 850 kHz switching frequency. It integrates 95 mΩ high-side and 69 mΩ low-side MOSFETs in VFQFPN 4×4-8L package, enabling high-efficiency point-of-load regulation for FPGA core supplies and consumer electronics power rails.

For engineers reviewing the ST1S41PHR datasheet, ST1S41PHR pinout, ST1S41PHR application, or ST1S41PHR equivalent, key selection criteria include verified 0.8 V feedback reference accuracy (±2.5%), cycle-by-cycle current limiting with foldback protection, internal soft-start duration (1 ms), thermal shutdown at 150 °C, and compatibility with all-ceramic output capacitor designs.

Technical Context

The ST1S41PHR implements peak current mode control with an integrated oscillator, slope compensation, and transconductance error amplifier featuring embedded RC compensation (70 kΩ/195 pF). Its control loop delivers 100 kHz bandwidth and 45° phase margin under typical 12 V_IN/1.2 V_OUT/4 A conditions.

It supports diode emulation via low-side current sensing, includes UVLO on both V_INA and V_INSW, and features hysteretic thermal shutdown (150 °C trip, 130 °C recovery) and dual-level overcurrent protection (OCP1 ≈ 5–7 A, OCP2 ≈ OCP1 + 1 A).

Key Specifications

Pinout & Package

ST1S41PHR is housed in a thermally enhanced VFQFPN 4 mm × 4 mm, 8-lead package with exposed ePAD for improved heat dissipation. Pin numbering follows top-view orientation per JEDEC MO-229 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS54340DDAR and MP2315GJ-Z, ST1S41PHR uniquely combines 4 A capability, dual-input architecture (V_INA/V_INSW), and guaranteed all-ceramic stability - making it optimal for high-density, high-accuracy FPGA/ASIC core supplies where layout simplicity and thermal robustness are critical.

Availability

ST1S41PHR is available at Aetrix Electronics and suitable for FPGA core supplies, digital TV point-of-load regulation, and optical storage drive power systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for ST1S41PHR 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, specializing in power management, microcontrollers, and analog ICs for automotive, industrial, and consumer markets.

The ST1S41 belongs to ST's high-efficiency synchronous buck regulator product line, designed specifically for compact, high-current point-of-load applications in set-top boxes, TVs, optical drives, and computing peripherals where thermal performance and ceramic-capacitor compatibility are essential.

FAQ

What is the maximum recommended PCB copper area for the ePAD under ST1S41PHR in a 2-layer board?

The ePAD must be connected to a minimum 100 mm² solid copper pour on the bottom layer, thermally vias (≥6 × 0.3 mm diameter) spaced ≤1 mm apart, and connected to internal ground planes if present. This achieves R_thJA ≈ 40 °C/W per datasheet thermal data, preventing thermal shutdown at 4 A continuous load in still air.

Can ST1S41PHR operate with only ceramic capacitors on input and output?

Yes - ST1S41PHR is explicitly characterized and guaranteed stable with all-MLCC designs. The internal compensation network and peak current mode control eliminate need for bulk electrolytics; recommended input is ≥10 µF 25 V X7R, output ≥47 µF 6.3 V X5R/X7R, placed within 3 mm of respective pins.

Does ST1S41PHR support forced PWM mode or only PFM at light load?

ST1S41PHR operates exclusively in fixed-frequency PWM mode across full load range. It does not enter pulse-frequency modulation (PFM) or discontinuous conduction mode (DCM); light-load efficiency is maintained via low quiescent current (2.5 mA typ.) and optimized gate drive, not frequency scaling.

What is the minimum output voltage achievable with ST1S41PHR and how is it set?

The minimum regulated output is 0.8 V, set by the internal reference voltage. To achieve this, connect FB directly to V_OUT; no resistor divider is needed. For higher outputs, use R1–R2 divider where V_OUT = 0.8 V × (1 + R1/R2), with R2 = 10 kΩ recommended for noise immunity and bias current error minimization.