Monolithic Power Systems Inc. MP163BGS-33

Overview

MP163BGS-33 from Monolithic Power Systems is a 700V non-isolated offline primary-side regulator with integrated 700V MOSFET and 3.3V LDO, delivering up to 4W output power in buck/boost/flyback topologies. It features 420mA peak current limit, 14Ω R_DS(on), <30mW no-load consumption, and green-mode frequency foldback for home appliance standby power and white goods auxiliary supplies.

For engineers reviewing the MP163BGS-33 datasheet, MP163BGS-33 pinout, MP163BGS-33 application, or MP163BGS-33 equivalent, this device serves as a self-biased, optocoupler-free CV regulator requiring precise FB resistor selection, minimum off-time validation, thermal derating for SOIC8-7B package, and LDO input voltage headroom management.

Technical Context

The MP163BGS-33 implements primary-side constant-voltage regulation using sampled feedback from a secondary-side capacitor (C3), referenced to a 2.55V internal error amplifier threshold. Its green-mode operation dynamically reduces both switching frequency and peak current under light load via frequency foldback and peak-current compression.

It integrates a 700V vertical DMOS power switch with 14Ω typical R_DS(on), an internally biased VCC supply derived from DRAIN, and a 3.3V LDO with 270mA peak current capability. Protection includes OLP (220ms delay), SCP (600mA threshold), open-loop detection (<0.5V FB), and thermal shutdown at 150°C with 30°C hysteresis.

Key Specifications

Pinout & Package

MP163BGS-33 is housed in a SOIC8-7B package (7-pin variant of standard SOIC-8, with pin 3 omitted). The exposed pad is not electrically connected and serves only for thermal relief.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar offline primary-side regulator applications.

Compared with MP163AGS-33, MP163BGS-33 delivers 100% higher peak current and 12.5% lower R_DS(on) in the same footprint, enabling higher power density; versus MP163CGS-33, it trades 57% lower peak current for reduced conduction loss sensitivity and tighter thermal envelope in compact enclosures.

Availability

MP163BGS-33 is available at Aetrix Electronics and suitable for home appliance control boards, white goods standby power, and IoT gateway auxiliary supplies requiring stable component supply across multi-year production cycles.

Supply support for MP163BGS-33 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, headquartered in Kirkland, WA, with global design and support centers.

The MP163 product line targets cost-sensitive, low-power offline AC/DC conversion where simplicity, reliability, and regulatory compliance are critical-designed specifically for primary-side regulation in consumer and industrial auxiliary power supplies.

FAQ

What is the recommended minimum off-time setting for MP163BGS-33 in buck topology?

The MP163BGS-33 has a fixed minimum off-time of 12μs (typical), which cannot be adjusted externally. This value limits maximum output power in discontinuous conduction mode and must be accounted for when selecting inductance and output capacitance to avoid regulation loss at light loads.

How does the integrated LDO interact with the main switching regulator output?

The LDO input (IN pin) must be supplied from the main output rail (e.g., buck output), requiring sufficient voltage headroom: VIN ≥ VOUT(LDO) + VDROPOUT (max 1.1V). For a 3.3V LDO, the main rail must be ≥4.4V; exceeding this causes excessive LDO power dissipation and thermal stress.

Can MP163BGS-33 operate without an external dummy load?

No. A minimum 3mA dummy load is required on the main output to ensure reliable sampling of output voltage by the feedback capacitor (C3). Omitting it causes poor no-load regulation and potential instability, especially in flyback configurations where energy transfer to C3 depends on inductor discharge.

What is the purpose of the EN pin on MP163BGS-33, and is it present in SOIC8-7B?

The EN pin is not bonded out in the SOIC8-7B package (MP163BGS-33); it is only available on SOIC16 variants (e.g., MP163BGSE-33). Therefore, MP163BGS-33 operates in always-on mode-startup is controlled solely by VCC UVLO thresholds (VCCON/VCCOFF), not external enable logic.

How is open-loop protection triggered, and what happens after detection?

Open-loop protection activates when FB voltage falls below 0.5V (typical), indicating loss of feedback signal or output short. The IC stops switching, discharges VCC via 16–24μA latch-off current, and restarts only after VCC drops below VCCpro (2.4–2.8V) and recharges above VCCOFF (5.4–5.6V), implementing a hiccup-mode recovery.

Does MP163BGS-33 support synchronous rectification?

No. MP163BGS-33 does not provide a gate drive signal for synchronous rectifiers. It is designed for use with external freewheeling diodes (e.g., UGC10JH) in buck, boost, or flyback topologies. Synchronous rectification requires external controller coordination and is not supported by its internal architecture.

What PCB layout considerations are critical for MP163BGS-33 thermal performance?

For SOIC8-7B, maximize copper area under the exposed pad (non-connected) and connect SOURCE and GND pins to large thermal planes. Keep high-dV/dt DRAIN traces short and远离 sensitive FB/VCC nodes. Use ≥2 oz copper and thermal vias under SOURCE/GND pads to achieve θJA ≤86°C/W and prevent thermal shutdown above 85°C ambient.