Monolithic Power Systems Inc. MP161AGS-5-P

Overview

MP161AGS-5-P from Monolithic Power Systems is an integrated power solution combining a 700V switching regulator, a fixed 5V low-dropout linear regulator (LDO), and two relay drivers in a single SOIC-16 package. It delivers 12V at up to 70mA from the switching stage and 5V at up to 100mA from the LDO, with ultra-low standby power enabled via STBY pin control. Designed for relay-driven MCU systems, it powers home automation controllers, industrial PLC I/O modules, and smart appliance mainboards.

For engineers reviewing the MP161AGS-5-P datasheet, MP161AGS-5-P pinout, MP161AGS-5-P application, or MP161AGS-5-P equivalent, key selection criteria include its 700V HV MOSFET R_DS(ON) of 17Ω (typ), 240mA peak current limit, integrated freewheeling diodes for relay coils, and dual-mode regulation (12V normal / 5.7V standby) - all critical for reliable, compact AC/DC power delivery in relay-centric embedded systems.

Technical Context

The MP161AGS-5-P implements constant-voltage (CV) regulation using internal loop compensation and a 1.225V feedback reference, with output set by either internal 450kΩ/4.1MΩ resistor divider (fixed 12V) or external resistors. Its 700V HV MOSFET operates with frequency and peak-current foldback to maintain high light-load efficiency while suppressing audible noise via peak-current modulation.

Standby mode reduces V_CC regulation from 12.5V to 5.7V, lowering switching losses; the LDO accepts input up to 30V and maintains 5V ±1% output with 300mV dropout at 50mA; relay drivers feature 2Ω on-resistance, 30V breakdown, and integrated freewheeling diodes - enabling direct drive of 12V/24V relays without external snubbers.

Key Specifications

Pinout & Package

MP161AGS-5-P is housed in a standard SOIC-16 package (5.3mm × 10.2mm, 1.27mm pitch) with exposed pad for thermal enhancement. 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 MP161BGS-5, the MP161AGS-5-P trades 40% lower peak current for tighter thermal envelope in compact enclosures; versus NCP1015ST100T3G, it eliminates three ICs and associated passives but fixes LDO voltage and relay count - optimizing for rapid time-to-market in standardized relay-control platforms.

Availability

MP161AGS-5-P is available at Aetrix Electronics and suitable for home automation hubs, industrial PLC I/O modules, and white goods mainboards requiring stable component supply across multi-year production cycles.

Supply support for MP161AGS-5-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 design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP161 product line targets cost-sensitive, space-constrained embedded systems requiring integrated AC/DC conversion, logic-level regulation, and electromechanical actuation - specifically engineered to replace multi-chip power solutions in smart infrastructure and appliance markets.

FAQ

What is the maximum recommended output power for MP161AGS-5-P in continuous operation?

The MP161AGS-5-P supports up to 0.84W (12V × 70mA) from its switching regulator and 0.5W (5V × 100mA) from its LDO under TA = 25°C with SOIC-16 on a 4-layer PCB. Derating is required above 70°C ambient; thermal shutdown activates at 150°C junction temperature, with 30°C hysteresis ensuring stable recovery.

Can MP161AGS-5-P drive relays rated for 24VDC coils?

Yes - the relay drivers support rail voltages up to 30V and feature integrated freewheeling diodes. For 24VDC relays, connect the coil between OUTA/OUTB and VIN (24V), ensuring coil current remains ≤100mA. The 2Ω on-resistance yields <200mV saturation drop, limiting driver dissipation to <20mW per channel.

How does standby mode affect the LDO output voltage?

Standby mode only regulates the switching regulator's V_CC output (from 12.5V to 5.7V); the LDO output remains fixed at 5.0V regardless of STBY state. Since VIN is typically tied to V_CC, the LDO input voltage drops in standby - but its dropout specification (300mV @ 50mA) ensures uninterrupted 5V output down to VIN = 5.3V.

Is an external feedback resistor divider required for 12V output?

No - the MP161AGS-5-P uses an internal 450kΩ/4.1MΩ resistor divider to set V_CC to 12V when FB is left open. An external divider is only needed to adjust output voltage (e.g., 15V or 24V); connecting FB to ground disables regulation and halts switching.

What protection mechanisms activate during a relay coil short circuit?

A shorted relay coil causes excessive current through OUTA/OUTB, triggering the LDO's overcurrent protection (not explicitly documented but inherent in VOVP and thermal limits). More critically, sustained overcurrent on VIN (e.g., from failed relay diode) raises VIN above 28V, activating VOVP and shutting down the entire IC within microseconds to prevent damage.

Does MP161AGS-5-P support synchronous rectification?

No - the MP161AGS-5-P uses asynchronous rectification with an external diode in the switching regulator output stage. Its architecture relies on a freewheeling diode for the relay drivers and does not provide gate drive signals or timing control for synchronous MOSFETs in the main power path.

What is the minimum recommended VCC capacitor value for stable start-up?

A 1μF X7R ceramic capacitor is recommended between VCC and GND. The datasheet confirms stable operation with "low μF or hundreds of nF" capacitance due to the internal HV current source's ability to recharge VCC rapidly - enabling compact designs without large electrolytic hold-up capacitors.