IRU3037A is a voltage-mode, fixed-frequency synchronous Buck (step-down) controller designed to build a low-cost point-of-load DC-DC converter on a single circuit board. Rather than integrating the power stage, the device drives two external N-channel MOSFETs (a high-side control FET and a low-side synchronous rectifier), which lets the designer size the converter for the exact output current the rail needs, commonly 3A and beyond. The controller runs from a single 5V or 12V bias rail and regulates its feedback pin to a 0.800V internal reference, so output voltages down to 1.8V, 1.5V and below are set with a simple resistor divider.

The "A" suffix marks the 400kHz variant of the family. The higher switching frequency, compared with the 200kHz IRU3037, shrinks the external inductor and output capacitors and suits space-constrained boards such as graphics cards and disk drives. A linearized, temperature-compensated transconductance gain cell sets the loop behaviour, while the SS/SD pin provides a programmable soft-start ramp and a logic-level shutdown using a single external capacitor.

Built-in undervoltage lockout on both the Vcc bias and the Vc gate-drive supply keeps the MOSFETs off until the rails are valid, and a feedback-based protection latch shuts the drivers down if the output collapses, for example when the high-side control FET fails short. The device is offered in an 8-pin SOIC (Narrow Body) and an 8-pin TSSOP, both available lead-free (PbF).

Note: Values are taken from the Infineon / International Rectifier IRU3037A datasheet (typical at Vcc=5V, Vc=12V over the rated temperature range). Confirm every parameter against the latest official datasheet before committing a design.

IRU3037A under ordering code 111-3013 is supplied in the 8-pin SOIC Narrow Body package, a 3.9mm-body gull-wing surface-mount outline on a 1.27mm pin pitch with a typical thermal resistance of 160°C/W (junction-to-ambient). The same die is also offered in an 8-pin TSSOP (thermal resistance 124°C/W) for tighter boards, and both options are available in a lead-free (PbF) finish that meets RoHS requirements. The narrow-body SOIC suits standard SMT assembly and AOI inspection on cost-sensitive power boards.

The 8-pin SOIC of IRU3037A is defined as follows:

• Pin 1 - Fb: Feedback input. The external resistor divider from the output ties here, and the loop regulates this pin to the 0.800V reference. The same node feeds the output undervoltage protection.
• Pin 2 - Vcc: Controller bias supply, 5V or 12V. Decouple with a local ceramic capacitor to Gnd close to the pin.
• Pin 3 - LDrv: Low-side gate drive. Drives the synchronous rectifier (lower) N-channel MOSFET.
• Pin 4 - Gnd: Signal and power ground reference for the controller.
• Pin 5 - HDrv: High-side gate drive. Drives the control (upper) N-channel MOSFET.
• Pin 6 - Vc: Gate-drive supply for the output drivers, up to 30V. Sets the gate-drive amplitude and is often tied to the 12V rail.
• Pin 7 - Comp: Error-amplifier output and loop-compensation node. An external R-C network sets the voltage-loop response against the output LC filter.
• Pin 8 - SS/SD: Soft-start and shutdown. An external capacitor sets the soft-start ramp; pulling the pin low shuts the controller down.

The parts below are reference alternatives across the Infineon power-conversion portfolio and the wider market. They are not drop-in replacements; verify reference voltage, switching frequency, drive topology, package and protection before substituting.

Selection Tips: Choose IRU3037A when a low-cost single-rail step-down with external MOSFETs and sub-2V output is the goal. Move to an integrated IR38060M / IR38063M when board area and BOM count outweigh the flexibility of external FETs, and to a multiphase controller such as IR3500A when the rail current exceeds what a single phase can deliver efficiently.

Infineon Technologies AG, headquartered in Neubiberg, Germany, is a leading supplier of power semiconductors and power-management ICs. The IRU3037 family originates with International Rectifier, the power-conversion pioneer that Infineon acquired in 2015, and it now sits within Infineon's DC-DC and point-of-load controller portfolio alongside the IRxxxx digital and analog power lines.

IRU3037A is a legacy IR voltage-mode synchronous Buck controller maintained for on-board DC-DC and memory-termination designs. For new high-density designs Infineon also offers integrated PowIRstage regulators (the IR38xxx family) and digital multiphase controllers, giving a migration path from the discrete-MOSFET IRU3037A approach to fully integrated solutions.