Monolithic Power Systems Inc. MP161BGS-33-P

Overview

MP161BGS-33-P from Monolithic Power Systems is a highly integrated power management IC combining a 700V switching regulator, a 3.3V low-dropout linear regulator, and two relay drivers in a single SOIC-16 package. It delivers 420mA typical peak current, 14Ω typical R_DS(ON), and ultra-low standby power via dedicated STBY control-enabling compact, reliable power stages for relay-driven MCU systems in home and industrial automation.

For engineers reviewing the MP161BGS-33-P datasheet, MP161BGS-33-P pinout, MP161BGS-33-P application, or MP161BGS-33-P equivalent, key selection criteria include its integrated 700V MOSFET with internal loop compensation, fixed 3.3V LDO output, dual-channel 2Ω relay drivers with freewheeling diodes, standby-mode voltage reduction to 5.7V (typ), and comprehensive protection suite including OLP, SCP, OTP, and BOP.

Technical Context

The MP161BGS-33-P implements constant-voltage regulation using an internal 1.225V feedback reference and 450kΩ lower resistor, enabling fixed 12V output or adjustable outputs via external divider. Its switching frequency folds back under light load to maintain high efficiency while suppressing audible noise through peak-current modulation.

Standby mode lowers V_CC regulation from 12.5V to 5.7V (typ), reducing power consumption without disabling LDO or relay drivers. The 2Ω on-resistance relay drivers accept 3.3–5V logic inputs and feature internal pull-downs, rail-to-rail 30V operation, and integrated freewheeling diodes-eliminating four external diodes per channel.

Key Specifications

Pinout & Package

MP161BGS-33-P is housed in a standard SOIC-16 package with exposed pad (thermal enhancement). Pin functions are validated per Monolithic Power Systems MP161 Rev. 1.01 datasheet, Section "PIN FUNCTIONS" (p.13).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar integrated power management applications.

Compared with MP161AGS-33, MP161BGS-33-P delivers 75% higher peak current and 18% lower R_DS(ON), enabling higher-power relay banks or extended thermal headroom. Versus MP161BGS-5, it provides native 3.3V logic compatibility-avoiding external regulators or level shifters in modern low-voltage MCU designs.

Availability

MP161BGS-33-P is available at Aetrix Electronics and suitable for home automation gateways, industrial PLC I/O modules, and commercial HVAC controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP161BGS-33-P 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, with over 20 years of leadership in integrated power solutions for industrial and consumer markets.

The MP161 product line was designed specifically for relay-based control systems in automation-integrating HV switching, precision LDOs, and robust drivers to replace discrete power trees and reduce design cycle time.

FAQ

What is the maximum recommended output power for MP161BGS-33-P in continuous operation?

The MP161BGS-33-P supports up to 2.5W output power in continuous conduction mode at 25°C ambient, based on its 420mA peak current limit, 14Ω R_DS(ON), and SOIC-16 thermal resistance (θ_JA = 80°C/W). Derating is required above 70°C ambient; full-load operation at 85°C ambient requires forced airflow or PCB copper pour.

Can MP161BGS-33-P drive relays directly without external flyback diodes?

Yes. Each relay driver (OUTA/OUTB) integrates a freewheeling diode rated for 100mA forward current and 1V drop at 100mA. This eliminates the need for external diodes in standard 12V/24V relay applications-verified in MPS Design Example (Rev. 1.01, p.10) with 100ms turn-off waveforms showing clean voltage clamping.

How does standby mode affect the 3.3V LDO output?

Standby mode only regulates the 700V switching regulator's V_CC output (from 12.5V → 5.7V); the 3.3V LDO remains fully operational and unaffected. VIN continues to receive power from the reduced V_CC rail, and VO maintains 3.3V regulation as long as VIN stays above 3.75V-confirmed in Typical Performance Characteristic "Standby Recovery" (p.11).

Is the FB pin required for basic operation with fixed 12V output?

No. With FB left open, the internal 450kΩ/4.1MΩ resistor divider enables fixed 12V output regulation. External resistors are only needed for adjustable outputs; connecting them overrides the internal divider. This configuration is validated in the Typical Application schematic (p.2) and requires no additional components for 12V use.

What is the minimum recommended input capacitor value for universal AC input (85–265VAC)?

For universal input with full-wave rectification, MPS recommends 1.5–2µF/W. For a 2W output, this translates to 3–4µF minimum. Using <2µF risks insufficient hold-up time, causing V_CC to dip below UVLO (3.6V) during AC zero-crossings-triggering brown-out protection and intermittent operation.

Does MP161BGS-33-P support synchronous rectification?

No. The MP161BGS-33-P uses asynchronous rectification with an external diode in the flyback path. Its architecture relies on the internal 700V MOSFET as the primary switch only; no secondary-side synchronous FET driver or timing control is included. Synchronous rectification would require external gate drivers and precise timing alignment.

How is over-temperature protection implemented and reset?

OTP triggers at 150°C junction temperature and latches off the IC until junction temperature falls below 120°C (30°C hysteresis). Recovery is automatic-no external reset signal required. Thermal shutdown is verified in Typical Characteristics (p.8) and protects against sustained overload or inadequate heatsinking in enclosed automation enclosures.