Monolithic Power Systems Inc. MP161BGS-5-Z

Overview

MP161BGS-5-Z from Monolithic Power Systems is an integrated power solution combining a 700V switching regulator, 5V low-dropout linear regulator, and dual-channel relay drivers in a single SOIC-16 package. It delivers 420mA peak current limit, 14Ω typical HV MOSFET R_DS(ON), and ultra-low standby power via programmable STBY control - enabling compact, self-contained power management for relay-driven MCU systems in home and industrial automation.

For engineers reviewing the MP161BGS-5-Z datasheet, MP161BGS-5-Z pinout, MP161BGS-5-Z application, or MP161BGS-5-Z equivalent, this device serves as a complete AC/DC front-end + logic-level power + relay interface - eliminating discrete HV FETs, external freewheeling diodes, and separate LDOs while supporting both fixed 12V switching output and 5V regulated rail with thermal, OVP, SCP, OLP, and brown-out protection.

Technical Context

The MP161BGS-5-Z implements constant-voltage regulation using internal loop compensation and feedback via FB pin or factory-fixed VCCREF (12.5V nominal), with light-load efficiency optimized by frequency and peak-current foldback. Its 700V integrated MOSFET operates with 21–25Ω R_DS(ON) at 125°C and supports up to 30V input on VIN and relay driver rails.

Standby mode lowers regulated VCC output from 12.5V to 5.7V (typical), reducing system idle power; relay drivers feature 2Ω on-resistance, integrated freewheeling diodes, and 30V breakdown voltage - all controlled by TTL/CMOS-compatible INA/INB inputs with internal 450kΩ pull-down resistors.

Key Specifications

Pinout & Package

MP161BGS-5-Z is housed in a standard SOIC-16 package (5.3mm × 10mm, 1.27mm pitch) with exposed pad not electrically connected. Pin functions are validated per Monolithic Power Systems MP161 Rev. 1.01 datasheet (April 2019).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP161AGS-5-Z, MP161BGS-5-Z delivers 75% higher peak current and lower conduction loss for thermally constrained relay boards; versus MP161BGS-33-Z, it enables direct interfacing with legacy 5V peripherals and simplifies mixed-voltage designs without external regulators.

Availability

MP161BGS-5-Z is available at Aetrix Electronics and suitable for home automation controllers, industrial PLC I/O modules, and smart appliance mainboards requiring stable component supply across multi-year production cycles.

Supply support for MP161BGS-5-Z 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 design centers in the US, China, and Taiwan.

The MP161 product line targets cost-sensitive, space-constrained relay-based control systems - integrating HV switching, LDO regulation, and driver stages to replace 6–10 discrete components in home/industrial automation power architectures.

FAQ

Can MP161BGS-5-Z operate directly from rectified 230VAC?

Yes - its 700V DRAIN pin accepts rectified universal AC input (85–265VAC). The internal HV current source starts regulation when DRAIN exceeds ~100V, enabling direct connection to bridge rectifier output without auxiliary winding or external startup circuitry.

What is the minimum recommended VCC capacitor value?

A 1μF ceramic capacitor is sufficient due to the internal HV current source's low operating current (4.1mA typ). This replaces traditional 10–47μF electrolytics, improving reliability and reducing footprint in space-limited designs.

How does standby mode affect relay driver operation?

Standby mode only reduces the 700V switching regulator output (VCC) from 12.5V to 5.7V - VIN and VO remain fully functional. Relay drivers continue operating normally since they are powered by VIN, which can be supplied independently (e.g., from backup battery or auxiliary rail).

Is external freewheeling diode required for relay coils?

No - integrated freewheeling diodes are present on both OUTA and OUTB. Each channel includes a silicon diode rated for continuous 100mA reverse current and 1V forward drop at 100mA, eliminating four external diodes and associated PCB area.

Does MP161BGS-5-Z support adjustable switching output voltage?

Yes - connecting an external resistor divider from VCC to FB overrides the internal 12V reference. With R_LOW = 450kΩ fixed internally, selecting R_UP sets output per V_OUT = V_REF × (1 + R_UP/450kΩ), where V_REF = 1.225V.

What protections activate during VIN overvoltage?

When VIN exceeds 28V (typ), the proprietary OVP circuit shuts down the switching regulator, disables VCC charging, and sinks 5mA from VIN to discharge external capacitors - preventing downstream damage to LDO, MCU, or relay drivers during line surges.

Can INA and INB be driven by 3.3V logic?

Yes - the absolute minimum high-level input voltage is 2.0V, and input hysteresis is 0.23V. 3.3V CMOS outputs (e.g., from ESP32 or Raspberry Pi Pico) meet VIH specification with 1.3V noise margin, ensuring reliable channel activation.