Renesas ISL91127II2AZ-T7A

Overview

ISL91127II2AZ-T7A from Renesas Electronics is a high-efficiency, fully synchronous 4-switch buck-boost DC/DC regulator delivering up to 2A continuous output current at 3.3V across 2.5V–4.35V input range. It features 2.5MHz switching frequency, 30µA quiescent current, and automatic seamless buck/boost mode transitions. Designed for single-cell Li-ion battery systems in portable medical and handheld devices.

For engineers reviewing the ISL91127II2AZ-T7A datasheet, ISL91127II2AZ-T7A pinout, ISL91127II2AZ-T7A application, or ISL91127II2AZ-T7A equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters, and real-world application implementation guidance - all specific to the ISL91127II2AZ-T7A adjustable-output variant in 4×4mm QFN.

Technical Context

The ISL91127II2AZ-T7A implements a proprietary 4-switch synchronous buck-boost topology with integrated P/N-channel MOSFETs (r_{DSON_P} = 32mΩ, r_{DSON_N} = 37mΩ) and dual-mode control logic enabling automatic transition between buck and boost operation as input voltage crosses output setpoint. Its 2.5MHz oscillator supports compact external components while maintaining stable regulation down to 1.0V output.

It uses a dedicated PVIN supply path for power stage and separate VIN for analog reference generation, with independent SGND and PGND pins to isolate high-frequency switching noise from feedback sensing. The MODE pin supports both auto-PFM/forced-PWM selection and external clock synchronization (2.75–3.25MHz).

Key Specifications

Pinout & Package

ISL91127II2AZ-T7A is housed in a 20-lead, 0.5mm pitch, 4mm × 4mm QFN package (RoHS-compliant, L20.4x4C drawing) with exposed thermal pad connected to PGND for enhanced thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2918GQ-Z and TPS63802DLAR, the ISL91127II2AZ-T7A uniquely balances adjustability (1.0–5.2V), compact 4×4mm footprint, and ultra-low 30µA quiescent current - making it optimal for space-constrained, battery-life-critical medical and consumer portable designs where output voltage may vary across product SKUs.

Availability

ISL91127II2AZ-T7A is available at Aetrix Electronics and suitable for handheld medical diagnostics, smartphone auxiliary rails, and portable RF transceiver power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL91127II2AZ-T7A 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

Renesas Electronics is a global semiconductor leader delivering microcontrollers, analog power, and SoC solutions for automotive, industrial, and IoT markets, with strong focus on energy-efficient power management ICs.

The ISL91127 family was designed specifically for advanced single-cell Li-ion battery systems in portable electronics, addressing the need for high-efficiency regulation across wide input-to-output voltage ratios without compromising transient response or quiescent power.

FAQ

What output voltage range does the ISL91127II2AZ-T7A support?

The ISL91127II2AZ-T7A supports an adjustable output voltage range from 1.0V to 5.2V, set via an external resistor divider on the FB pin. Its internal reference voltage is 0.800V (±13mV), enabling precise programming - for example, R1 = 1MΩ and R2 = 324kΩ yields 3.3V output. This range accommodates diverse system rails including MCU cores, RF bias, and sensor interfaces without requiring multiple fixed-output variants.

How does the ISL91127II2AZ-T7A handle input voltages near the output voltage?

The ISL91127II2AZ-T7A uses Renesas' proprietary buck-boost algorithm to rapidly and seamlessly alternate between buck and boost modes when PVIN approaches VOUT, maintaining tight regulation with very low output ripple (<5mV_pp). Unlike hybrid controllers requiring external mode selection, this automatic transition occurs without interruption or control overhead - critical for maintaining system stability during battery voltage sag in portable devices.

What is the purpose of the separate VIN and PVIN pins on the ISL91127II2AZ-T7A?

The ISL91127II2AZ-T7A separates VIN (analog supply for reference and control circuitry) from PVIN (power input for switching stage) to prevent high-frequency switching noise from modulating the internal 0.8V reference. VIN must be supplied within 1.8V–5.5V and decoupled independently; PVIN powers the 4-switch FET array. This dual-supply architecture ensures ±2% output accuracy across temperature and load, even under heavy transient conditions.

Does the ISL91127II2AZ-T7A include short-circuit protection?

Yes, the ISL91127II2AZ-T7A provides short-circuit protection by continuously monitoring the FB pin voltage. When feedback drops below threshold, the PWM oscillator frequency is reduced to limit power dissipation while maintaining active current limiting (P-channel peak limit: 3.7–5.0A). Recovery is automatic once fault condition clears - no latch-off or external reset required. This behavior is validated across –40°C to +85°C ambient.

Can the ISL91127II2AZ-T7A be synchronized to an external clock?

Yes, the MODE pin of the ISL91127II2AZ-T7A accepts an external clock signal in the 2.75MHz to 3.25MHz range, allowing synchronization with system timing sources to reduce beat frequencies and EMI. When driven with a clean CMOS-level clock, the device locks to the external frequency while retaining all internal protections and regulation accuracy - verified in Renesas Application Note AN1723.