STMicroelectronics STBB2J29-R

Overview

STBB2J29-R from STMicroelectronics is a dual-mode buck-boost DC-DC converter delivering fixed 2.9 V / 3.4 V outputs from 2.4–5.5 V input, featuring 2.5 MHz switching, ±2% output voltage tolerance, and integrated N/P-channel MOSFETs with <350 mΩ R_DS(on). It enables battery-powered memory card and cellular phone power rails where input may fall below, equal, or exceed output voltage.

For engineers reviewing the STBB2J29-R datasheet, STBB2J29-R pinout, STBB2J29-R application, or STBB2J29-R equivalent, key selection criteria include bypass mode quiescent current (≤10 µA), auto/PWM mode control via MODE pin, VSEL-based dual-output selection, and Flip Chip 20-bump (2.1 × 1.8 mm) thermal performance (R_thJA = 80 °C/W).

Technical Context

The STBB2J29-R implements average current-mode control with feed-forward compensation to stabilize regulation across buck, boost, and buck-boost transition regions-especially critical when VIN ≈ VOUT. Its four internal switches (two P-ch, two N-ch) enable seamless mode transitions without external reconfiguration.

Dual operation modes are hardware-selectable: MODE pin high forces continuous PWM for optimal transient response (e.g., RF PA bursts); MODE pin low enables automatic pulse-skipping at light load, reducing I_q to 35–50 µA while maintaining ±3% output accuracy in PS mode. Bypass mode (BP high + EN high) shorts VIN to VOUT via P-ch switches, limiting I_q to ≤10 µA.

Key Specifications

Pinout & Package

STBB2J29-R uses a Flip Chip 20-bump package (2.1 mm × 1.8 mm, 0.4 mm pitch) with exposed thermal pad on bottom side. Pin mapping is validated per STMicroelectronics DocID022745 Rev 9 (Figure 5, Table 5).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck-boost converter applications.

Compared with TPS63020DSJR and ADP5070ACPZ-R7, STBB2J29-R uniquely combines factory-trimmed dual-output selection, sub-10 µA bypass mode, and 2.5 MHz operation in a 2.1 × 1.8 mm Flip Chip package-making it optimal for space- and battery-life-constrained dual-rail portable designs.

Availability

STBB2J29-R is available at Aetrix Electronics and suitable for memory card power supplies, cellular phone baseband subsystems, portable media player audio codecs, and wireless headset PMU subsystems requiring stable component supply across automotive-grade temperature ranges and long production lifecycles.

Supply support for STBB2J29-R 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, sensors, and analog devices for industrial, automotive, and consumer markets.

The STBB2 product line delivers highly integrated, small-footprint buck-boost converters targeting battery-powered portable electronics where input voltage varies widely and efficiency at light load is critical.

FAQ

What is the function of the VSEL pin on STBB2J29-R?

The VSEL pin selects between the two factory-programmed output voltages: pulling VSEL low (GND) configures 2.9 V output, while pulling VSEL high (VIN) selects 3.4 V output. This eliminates external feedback resistors and enables dual-rail support from a single BOM item-confirmed in Table 9 and Section 7.4 of STMicroelectronics DocID022745 Rev 9.

How does bypass mode reduce power consumption in STBB2J29-R?

Bypass mode activates when both EN and BP pins are high, turning on internal P-channel switches to directly connect VIN to VOUT. This bypasses the switching regulator entirely, reducing quiescent current to ≤10 µA-verified in Table 6 (Bypass mode I_q = 5–10 µA) and Section 7.3. It is ideal for system idle states where regulation is unnecessary.

Can STBB2J29-R operate with input voltage lower than its output voltage?

Yes. STBB2J29-R is a true buck-boost converter capable of regulating output when VIN < VOUT (e.g., 2.4 V input → 2.9 V output), VIN = VOUT, or VIN > VOUT (e.g., 4.2 V input → 3.4 V output). This is enabled by its four-switch architecture and average current-mode control, as detailed in Section 7 General Description and Figure 14 load transient waveforms.

What thermal derating applies to STBB2J29-R at 800 mA output current?

At 800 mA continuous output, STBB2J29-R requires ≤80 °C/W junction-to-ambient thermal resistance (per Table 4) to maintain T_J ≤ 150°C. On a standard JEDEC 2s2P 4-layer PCB, this allows full-load operation up to +85°C ambient-verified by thermal shutdown threshold (150°C) and hysteresis (20°C) in Section 7.5.3 and Table 6.