Richtek USA Inc. RT7236GQW

RT7236GQW Product Summary and Description

The Richtek RT7236GQW is a high-performance synchronous step-down (buck) DC/DC converter IC, distinguished by its ability to deliver up to 5A output current from a wide 4.5V to 18V input supply. Packaged in a compact 10-lead WDFN 3x3mm footprint with an exposed pad for thermal performance, the RT7236GQW finds application in high-density, power-sensitive designs such as industrial automation, computer and peripheral supplies, LCD TVs/monitors, and point-of-load (POL) regulation for advanced FPGAs, ASICs, and DSPs.

The device utilizes Richtek’s proprietary Advanced Constant On-Time (ACOT®) control, enabling a fast transient response and excellent efficiency across an extended load and input range. With its adjustable output, flexible soft-start, synchronous operation, and rich protective features, RT7236GQW provides a modern platform for engineers optimizing for efficiency, size, and system reliability.

Main Characteristics and Benefits of RT7236GQW

The RT7236GQW integrates several device-specific features tailored for demanding embedded power environments:

Wide input range (4.5V to 18V) accommodates common 5V, 12V, and intermediate bus rails

5A continuous output capability, supporting powerful load requirements

High efficiency (up to 95%) enabled by internal low RDS(on) (35mΩ) N-MOSFETs and synchronous switching

ACOT® mode facilitates rapid load transient response and stable operation with all ceramic output capacitors, reducing the need for high ESR types and supporting tightly regulated rails

Adjustable output voltage from 0.765V up to 8V, catering to a wide variety of system core/bus rails

Fixed 650kHz switching frequency that remains stable across different VIN and load conditions

Discontinuous mode operation at light load for increased efficiency (RT7236GQW)

Flexible soft-start via external capacitor, mitigating inrush current and output overshoot during power-up

RoHS compliant, halogen-free, and designed for modern lead-free manufacturing environments

These features position the RT7236GQW as a versatile buck regulator for compact and energy-sensitive systems, as well as cost- and board space-sensitive designs.

RT7236GQW Internal Structure and Design Features

At the core of the RT7236GQW is Richtek’s ACOT® mode control, which minimizes external compensation and ensures a constant on-time policy. This approach dynamically sets switch on-time based on VIN and VOUT conditions, maintaining a consistent switching frequency even during significant line/load variations. It enables the use of lower-value ceramic capacitors to reduce footprint and cost, while maintaining low ripple and fast transient response.

The IC’s power stage includes fully integrated high-side and low-side N-channel MOSFETs, simplifying board routing and minimizing external component count. Internal logic manages the transition between continuous conduction mode (CCM) and discontinuous mode (DCM), maximizing efficiency in both heavy and light load conditions. The succinct 10-pin WDFN package includes a Power Good (PGOOD) status indicator and supports straightforward layout for tight designs.

RT7236GQW Operation Modes and System Compatibility

The RT7236GQW automatically operates in a discontinuous mode at light loads to further enhance efficiency—particularly valuable in battery-powered or always-on applications. Its fast soft-start function is customizable via an external capacitor, ascertaining seamless ramp-up of output voltage and minimizing voltage overshoot that could otherwise stress downstream loads.

Enable (EN) control logic supports flexible system-level sequencing and remote/digital enable, with provisions for external logic or resistor-divided lockout thresholds to match complex power management schemes in multi-rail or multi-power-domain systems.

The output voltage is precisely set by an external resistive divider, following the feedback reference of 0.765V, and can be programmed anywhere from 0.765V to 8V, meeting the requirements of core, peripheral, and I/O voltage rails.

RT7236GQW Protection Features, Reliability, and Safety Measures

To ensure robust operation even in adverse conditions, the RT7236GQW offers comprehensive fault and protection features suited to industrial and mission-critical systems:

Cycle-by-cycle current limiting protects the device and load by monitoring the low-side MOSFET and employing a wide hysteresis band, preventing overshoot and damage during overload or short-circuit events.

Output overvoltage and undervoltage protection automatically shuts down or restarts the converter if the output moves outside predefined safe limits (using hiccup mode in WDFN-10L, matching the RT7236GQW variant).

Thermal (OTP) shutdown disables switching if junction temperature exceeds 150°C, with automatic restart after cooldown, ensuring longevity and safety.

Input undervoltage lockout (UVLO) prevents erratic operation when VIN is below its recommended threshold, avoiding inadvertent start-up or latch-up events.

These mechanisms ensure device and system-level reliability, especially in environments with unpredictable voltages or power cycling.

Electrical and Thermal Performance Aspects of RT7236GQW

Safe and optimal use of the RT7236GQW requires attention to thermal design and electrical rating compliance:

Maximum ratings: VIN range of -0.3V to 20V (absolute max), with recommended operation between 4.5V and 18V; junction temperatures up to 150°C absolute, with safe operation up to 125°C.

Thermal resistance for the WDFN-10L 3x3 is 60°C/W junction-to-ambient; care should be taken to not exceed its 1.67W power dissipation limit at 25°C ambient, factoring in derating for higher operating temperatures.

Proper layout (short, wide traces; low-inductance input/output capacitors placed close to IC), robust ground planes, and adequate cooling are essential for maximizing efficiency and reliability.

Use of ceramic capacitors (X7R, X5R types) for input/output decoupling is recommended, with a minimum 1μF for internal regulator decoupling and boot capacitance.

Output inductor and capacitors should be chosen to balance ripple, transient response, and efficiency, with design equations provided in the application section for precise component value calculation.

RT7236GQW Usage Recommendations and Common Applications

The device’s feature set and flexible programmability make the RT7236GQW suitable for:

Industrial control and commercial low power systems requiring programmatically set rails in compact form factors.

Computer peripherals and display power supplies that must satisfy modern high-efficiency and low noise requirements.

Powering sensitive loads in green electronics, home appliances, and energy-efficient computing, where strict inrush management and load protection are vital.

Supplying point-of-load voltages for high-end ASICs, DSPs, and FPGAs where fast dynamic load response and output adjustability are needed.

Designs with multi-stage power rails and complex sequencing/enable logic, leveraging the flexible EN and customizable soft-start functionality.

Alternative or Substitute Options for RT7236GQW

In situations where the RT7236GQW cannot be used due to supply constraints, package limitations, or specific mode requirements, other variants within the Richtek RT7235/36/39/40 family provide close alternatives:

RT7235 (TSSOP-14/WDFN-10L): Nearly identical, but operates exclusively in forced continuous conduction mode—preferable where fixed-frequency operation is critical.

RT7239 and RT7240 (SOP-8/Exposed Pad): Also 5A, 18V synchronous converters, with RT7240 supporting DCM like RT7236GQW.

For layouts requiring a different pinout or form factor, TSSOP or SOP alternatives within this family can be considered directly, as they share core ACOT® architecture, protections, and performance specifications.

Additionally, evaluating competitors’ synchronous buck converters with ACOT/constant on-time control and 5A capability within the 4.5V–18V range may serve as substitutes if Richtek’s supply is not available.

Conclusion

The Richtek RT7236GQW is an advanced, highly efficient synchronous buck converter designed for applications where power density, rail flexibility, rapid transient response, and comprehensive protection are essential. Its efficient ACOT® topology, wide input and output range, and compact WDFN package make it a compelling choice for engineers and procurement professionals seeking a cost-effective, robust, and highly integrable DC/DC regulator. By leveraging its programmability and rich set of reliability features, the RT7236GQW enables streamlined power subsystem design for today’s demanding electronics platforms.