STMicroelectronics ST1PS01AJR

Overview

ST1PS01AJR from STMicroelectronics is a nano-quiescent synchronous step-down DC-DC converter in Flip-Chip8 package, delivering up to 400 mA output current with 500 nA quiescent current at 3.6 V input and 1.9 V fixed output (D0=0, D1=0). It operates from 1.8 V to 5.5 V input, features 100% duty cycle mode, Power Good open-drain flag, and is optimized for ultra-low-power wearable systems powered by single-cell Li-Ion batteries.

For engineers reviewing the ST1PS01AJR datasheet, ST1PS01AJR pinout, ST1PS01AJR application, or ST1PS01AJR equivalent, key selection criteria include its 1.9 V factory-set output voltage, dynamic digital voltage selection capability (D0/D1), 94% efficiency at 1 mA load (3.6 V → 3.3 V), ±1.5% output accuracy, and integrated soft-start with 1.7 ms startup delay - all critical for energy-constrained portable sensor and BLE endpoint designs.

Technical Context

The ST1PS01AJR implements peak current control (PCC) with hysteretic switching, enabling seamless PFM/PWM transition across load ranges from 100 µA to 400 mA. Its internal architecture includes a dedicated zero-crossing comparator, fixed soft-start ramp, and embedded output discharge MOSFET (30 Ω on-resistance) activated during shutdown or UVLO.

It supports 100% duty cycle operation when VIN approaches VOUT + 300 mV, directly connecting input to output via the high-side MOSFET (R_DS(on) = 0.38 Ω typ.). The PGOOD comparator asserts high-impedance state when VOUT reaches ≥97.5% of target, with hysteresis of −3.2% relative to selected output.

Key Specifications

Pinout & Package

ST1PS01AJR uses the Flip-Chip8 package (1.14 × 1.44 mm, 0.5 mm pitch), optimized for ultra-thin wearable PCBs with bottom-soldered bumps and minimal footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nano-power synchronous buck converter applications.

Compared with ST1PS01AJR, the TPS62840 offers lower quiescent current but sacrifices voltage flexibility and system-level monitoring; the ADP5302 achieves smaller size and lower IQ but removes critical features for autonomous sensor nodes - making ST1PS01AJR the only option supporting dynamic voltage scaling, PGOOD, and 100% dropout-free operation in a 1.14×1.44 mm package.

Availability

ST1PS01AJR is available at Aetrix Electronics and suitable for wearable sensors, BLE endpoints, and industrial wireless nodes requiring stable component supply with guaranteed long-term availability and full traceability.

Supply support for ST1PS01AJR 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 microcontrollers, power management ICs, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The ST1PS01 series belongs to ST's nano-power DC-DC converter product line, engineered specifically for space- and energy-constrained IoT edge nodes where PCB thickness, battery lifetime, and startup reliability under weak sources are primary design constraints.

FAQ

What is the factory-configured output voltage of ST1PS01AJR?

The ST1PS01AJR is pre-configured for 1.9 V output, achieved when D0 = 0 and D1 = 0 (per Table 7 in DS12799 Rev 6). This voltage is internally hardwired and does not require external resistors. The device retains full dynamic reconfiguration capability - changing D0/D1 states during operation adjusts VOUT to 2.0 V, 2.1 V, or 2.8 V as needed.

Does ST1PS01AJR support true 100% duty cycle operation, and what is its practical benefit?

Yes - ST1PS01AJR enters 100% duty cycle mode when VIN falls to VOUT + 300 mV (e.g., ~2.2 V for 1.9 V output), turning off switching and connecting VIN directly to VOUT via the high-side MOSFET. This eliminates dropout and sustains regulated output during deep battery discharge, extending usable runtime in single-cell Li-Ion applications beyond conventional buck converters.

How is Power Good (PGOOD) functionality implemented, and what threshold does it monitor?

PGOOD is an open-drain output that goes high-impedance when VOUT reaches ≥97.5% of its selected value (e.g., ≥1.85 V for 1.9 V output), and pulls low when VOUT drops below that threshold minus 3.2% hysteresis (e.g., <1.79 V). It requires an external pull-up resistor and provides hardware-level power sequencing feedback to host MCUs without software polling.

What external components are required for basic ST1PS01AJR operation, and what are their critical specifications?

Only four passive components are required: a 10 µF low-ESR ceramic input capacitor (0603), a 10 µF low-ESR ceramic output capacitor (0603), a 2.2 µH shielded inductor (0806), and a 1 MΩ pull-up resistor on PGOOD. Input/output capacitors must be placed adjacent to VIN/VOUT pins with short, low-inductance traces to ensure stability and minimize ripple under transient loads up to 400 mA.