Renesas IW1791-37B

Overview

The iW1791-37B from Renesas Electronics is a primary-side AC/DC PWM controller for rapid charge applications, supporting USB Power Delivery (USB PD) and Qualcomm Quick Charge 3.0 protocols with 10mV DLNK voltage step resolution. It delivers multi-level constant voltage/current regulation without secondary feedback, achieves <20mW no-load power at 230VAC/5V output, and operates in quasi-resonant mode for high efficiency.

For engineers reviewing the iW1791-37B datasheet, iW1791-37B pinout, iW1791-37B application, or iW1791-37B equivalent, key selection considerations include DLNK-based digital communication capability, source-charging VCC architecture, 8-pin SOIC package, and support for 3.6V–12V QC3.0 output with 200mV increments and USB PD PPS compliance.

Technical Context

The iW1791-37B implements Renesas' PrimAccurate™ technology to enable primary-side regulation with tight CV/CC control across multiple output levels, eliminating loop compensation components and optocoupler-based feedback. Its proprietary DLNK protocol enables bidirectional digital communication over a single optocoupler for voltage requests, current limits, undershoot detection, and OVP signals.

It integrates source-charging VCC startup to remove external active start-up circuits, supports multi-mode PWM/PFM operation for load-adaptive efficiency, and features SmartDefender+™ protection against soft shorts, half-shorts, and output over-voltage/over-current faults without latching.

Key Specifications

Pinout & Package

Package: 8-lead SOIC-8 with standard JEDEC MS-012AC dimensions and exposed pad not required.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar primary-side rapid charge controller applications.

Compared with MP6908A and UCC28780, the iW1791-37B provides native DLNK-based digital communication, eliminates secondary feedback components, and delivers true 10 mV PPS resolution without external processing-reducing design cycle time and bill-of-materials for USB PD + QC3.0 dual-protocol adapters.

Availability

iW1791-37B is available at Aetrix Electronics and suitable for USB PD fast charging adapters, QC3.0 wall chargers, and multi-protocol portable power supplies requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for iW1791-37B 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 Corporation is a global semiconductor leader delivering microcontrollers, analog, power, and SoC products for automotive, industrial, infrastructure, and IoT applications.

The iW1791-37B belongs to Renesas' Rapid Charge™ AC/DC controller product line, engineered specifically for high-efficiency, digitally controlled primary-side regulation in compact USB PD and QC-compliant power adapters.

FAQ

What is the DLNK voltage step resolution supported by the iW1791-37B?

The iW1791-37B supports a 10 mV DLNK voltage step resolution, which satisfies the USB Power Delivery Programmable Power Supply (PPS) specification and enables precise QC3.0 voltage control in 200 mV increments. This resolution is confirmed in the Ordering Information table of the iW1791 Rev. 1.7 Product Summary, where iW1791-37B is explicitly listed with "10mV/Step" under DLNK Voltage Information Resolution.

Does the iW1791-37B require an external active start-up (ASU) circuit?

No, the iW1791-37B does not require an external active start-up circuit due to its integrated source-charging VCC technology. This feature charges the VCC capacitor directly from the SOURCE pin before startup, enabling ultra-low no-load power consumption (<20 mW at 230 VAC/5 V output). The iW1791-37B datasheet confirms this architecture eliminates the need for ASU while maintaining stability across universal AC inputs.

Which rapid charge protocols does the iW1791-37B natively support?

The iW1791-37B natively supports USB Power Delivery (including PPS), Qualcomm Quick Charge 2.0 and 3.0, and other proprietary rapid charge protocols when paired with Renesas secondary-side controllers using the DLNK interface. The iW1791-37B Product Summary states it "can implement various rapid charge protocols" including USB PD and QC2.0/QC3.0, with output voltage configurations up to 20 V for PD and 3.6–12 V for QC3.0.

What protection features are built into the iW1791-37B?

The iW1791-37B integrates SmartDefender+™ control for soft short mitigation, plus built-in protections against output short-circuit (including soft and half short), output over-voltage, and output over-current. It also includes auxiliary winding open protection via the CFG pin and undershoot detection via DLNK. These protections operate without latching, allowing automatic recovery after fault clearance-confirmed in Section 2 Features and Section 4 Pinout Description of the iW1791-37B datasheet.

Is the iW1791-37B pin-compatible with other iW1791 variants like iW1791-02 or iW1791-27B?

Yes, the iW1791-37B is pin-compatible with all iW1791 family members, including iW1791-02 and iW1791-27B, as they share the same SOIC-8 package and identical pinout (GND, DLNK, VSENSE, CFG, ISENSE, SOURCE, GATE, VCC). The differences between variants are functional-such as DLNK step resolution, kCC configuration, and VIPK clamp settings-and do not affect physical layout or electrical connectivity. This is verified in the Ordering Information table and Figure 4.1 of the iW1791 Rev. 1.7 Product Summary.