Monolithic Power Systems Inc. MP161AGS-33-Z

Overview

MP161AGS-33-Z from Monolithic Power Systems is a highly integrated power solution combining a 700V switching regulator, 3.3V low-dropout linear regulator, and dual-channel relay drivers in a single SOIC-16 package. It delivers 12V/70mA and 3.3V/50mA outputs with ultra-low standby power, integrated freewheeling diodes, and on-resistance of 2Ω per relay driver - designed for relay-controlled home automation gateways requiring compact, self-contained power management.

For engineers reviewing the MP161AGS-33-Z datasheet, MP161AGS-33-Z pinout, MP161AGS-33-Z application, or MP161AGS-33-Z equivalent, key selection criteria include its 17Ω HV MOSFET R_DS(ON), 240mA peak current limit, standby-mode V_CCSTBY = 5.7V regulation, integrated OLP/SCP/OTP protections, and dual 3.3–5V logic-compatible relay drive capability.

Technical Context

The MP161AGS-33-Z implements constant-voltage (CV) regulation via internal loop compensation and feedback reference V_REF = 1.225V, with fixed 12V output enabled by internal 450kΩ/4.1MΩ resistor divider. Its 700V HV MOSFET operates with programmable t_minoff = 9.5μs and t_maxon = 25μs timing constraints to enforce CCM/DCM boundary control and prevent brown-out under light load.

Standby mode is triggered by high-level STBY input, reducing regulated V_CC from 12.5V to 5.7V to cut switching losses; relay drivers use internal pull-down resistors (450kΩ) and R-C noise filters, with rail-to-rail operation up to 30V and integrated freewheeling diodes limiting external component count.

Key Specifications

Pinout & Package

MP161AGS-33-Z is housed in a standard SOIC-16 package with exposed pad (no thermal pad designation in datasheet), rated for 1.56W continuous power dissipation at +25°C ambient and θ_JA = 80°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP161BGS-33-Z, the MP161AGS-33-Z trades 280mA additional peak current and 3Ω lower R_DS(ON) for tighter cost control and sufficient margin in sub-1W home automation loads; versus MPQ161AGS-33-AEC1-Z, it omits automotive qualification overhead while retaining identical functional behavior in industrial environments.

Availability

MP161AGS-33-Z is available at Aetrix Electronics and suitable for home automation gateways, industrial PLC I/O modules, and white goods control boards requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP161AGS-33-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, and global manufacturing partnerships.

The MP161 product line targets cost-sensitive, space-constrained relay-based systems in home and industrial automation, integrating HV switching, LDO regulation, and relay drive to eliminate discrete power subsystems.

FAQ

What is the maximum recommended output power for MP161AGS-33-Z in continuous operation?

The MP161AGS-33-Z supports up to 840mW (12V × 70mA) on the switching regulator and 165mW (3.3V × 50mA) on the LDO. Total continuous output is limited by thermal dissipation: at +25°C ambient, 1.56W max power dissipation allows combined operation within SOIC-16 thermal limits, assuming adequate PCB copper area and airflow.

Can MP161AGS-33-Z drive relays directly from 24VAC lines?

No - the relay drivers (OUTA/OUTB) accept logic-level inputs (INA/INB) but require DC supply from VIN (3.9–29V). The 700V switching regulator can be powered from rectified 24VAC (≈34VDC), but relay coils must be DC-rated and connected between OUTx and VIN, not AC line. AC coil driving requires external triac/driver.

How does standby mode affect the 3.3V LDO output?

Standby mode only regulates the VCC node (switching regulator output) down to 5.7V; the LDO (VO) remains fully active at 3.3V regardless of STBY state. This ensures MCU and logic stay powered during standby while relay coils are de-energized and switching losses minimized.

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

No - the MP161AGS-33-Z uses an internal 450kΩ/4.1MΩ resistor divider to set fixed 12V output. External resistors are only needed if adjusting output voltage (e.g., to 15V or 24V); connecting them to FB overrides the internal divider and references regulation to V_REF = 1.225V.

What protection features activate during a short circuit on the 12V output?

Short-circuit protection (SCP) triggers immediately when sensed current exceeds 525mA after leading-edge blanking (t_LEB2 = 180ns). The IC halts switching, discharges VCC via 28μA latch-off current, and remains latched until VCC falls below 2.7V - preventing thermal runaway and enabling safe auto-recovery after fault removal.

Does MP161AGS-33-Z support adjustable frequency or synchronous rectification?

No - the MP161AGS-33-Z uses fixed internal oscillator architecture with frequency foldback based on load. It does not support external frequency programming or synchronous rectifier control; the secondary-side rectification is handled by external diodes in the application circuit.

What is the minimum input voltage required for reliable start-up?

Start-up requires DRAIN voltage ≥400V to initiate HV current source operation, corresponding to ~280VAC input after bridge rectification. Below this, VCC cannot reach V_HVoff = 4.65V to enable switching. For lower AC inputs, an auxiliary start-up circuit is required.