NXP Semiconductors EM773FHN33,551

Overview

EM773FHN33,551 from NXP Semiconductors is a 32-bit ARM Cortex-M0 energy metering IC designed for smart metering applications. It integrates a metrology engine with two current inputs (I_HIGHGAIN, I_LOWGAIN) and one voltage input (VOLTAGE), delivers up to 48 MHz CPU operation, includes 32 kB flash and 8 kB SRAM, and supports RS-485 UART, SPI, and Fast-mode Plus I²C for utility-grade sub-metering in plug-in or industrial panel meters.

For engineers reviewing the EM773FHN33,551 datasheet, EM773FHN33,551 pinout, EM773FHN33,551 application, or EM773FHN33,551 equivalent, key selection criteria include metrology accuracy (1 % over 1:400 dynamic range), HVQFN33 package compatibility, 3.3 V single-supply operation, Deep power-down wake-up via PIO1_4/WAKEUP, and support for non-billing active/reactive/apparent power calculation without CPU intervention.

Technical Context

The EM773FHN33,551 implements a dedicated metrology engine that autonomously computes active power (W), reactive power (VAr), apparent power (VA), power factor, Vrms, and Irms - eliminating real-time CPU load during measurement cycles. Its clock system combines a 12 MHz ±1 % trimmed IRC oscillator, a 1–25 MHz crystal oscillator, and a programmable watchdog oscillator (7.8 kHz–1.8 MHz), all feeding into a PLL capable of generating stable CPU clocks up to 48 MHz.

Digital subsystems include three counter/timers (two 32-bit, one 16-bit) with capture/match functionality, a 25-pin GPIO array supporting edge/level interrupts and high-current drive (20 mA on select pins), and serial interfaces with hardware FIFOs: UART (3.125 Mbit/s, RS-485 support), SPI (25 Mbit/s master), and I²C (1 Mbit/s Fast-mode Plus with multi-address recognition).

Key Specifications

Pinout & Package

HVQFN33 package: 33-terminal, thermally enhanced, no-lead plastic quad flat package with 7 mm × 7 mm body and 0.85 mm height. Exposed thermal pad (Pin 33/VSS) must be soldered to PCB ground plane for optimal thermal performance and metrology stability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar energy metering applications.

Compared with ATTINY1616-MNR and STM32G071KBT6, the EM773FHN33,551 provides verified 1 % metrology accuracy out-of-box, eliminates firmware metrology development, and integrates RS-485 physical layer support - reducing time-to-certification for IEC 62053-compliant sub-metering designs.

Availability

EM773FHN33,551 is available at Aetrix Electronics and suitable for smart plug meters, industrial sub-meters, and smart appliance monitors requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for utility-grade deployments.

Supply support for EM773FHN33,551 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The EM773 product line was engineered specifically for non-billing smart energy metering - delivering integrated metrology, low-power operation, and industrial serial interfaces in a single chip to replace multi-component metering subsystems.

FAQ

What is the metrology accuracy specification of the EM773FHN33,551?

The EM773FHN33,551 achieves 1 % accuracy for active, reactive, and apparent power measurements across a 1:400 dynamic current range (e.g., 16 A down to 40 mA at 230 V/50 Hz). This specification is validated for scalable input sources up to 230 V/50 Hz/16 A and 110 V/60 Hz/20 A, with metrology engine performing all calculations autonomously - no CPU intervention required during sampling.

Does the EM773FHN33,551 support RS-485 communication natively?

Yes, the EM773FHN33,551 includes a dedicated UART peripheral with built-in RS-485 support, including 9-bit addressing mode and hardware flow control signals (RTS/CTS/DTR). It operates up to 3.125 Mbit/s with a 16-byte transmit/receive FIFO and fractional baud rate generator - enabling reliable communication across variable crystal frequencies without external transceivers.

What package type and thermal characteristics does the EM773FHN33,551 use?

The EM773FHN33,551 is supplied in an HVQFN33 package (7 mm × 7 mm × 0.85 mm) with an exposed thermal pad (Pin 33/VSS). This thermally enhanced construction requires soldering the pad to a PCB ground plane to maintain metrology engine stability and ensure sustained 48 MHz CPU operation under ambient temperatures up to 85 °C.

Can the EM773FHN33,551 operate from a crystal oscillator or internal RC oscillator?

Yes, the EM773FHN33,551 supports three clock sources: a 1–25 MHz external crystal oscillator, a 12 MHz ±1 % trimmed internal RC oscillator (IRC), and a programmable watchdog oscillator (7.8 kHz–1.8 MHz). After reset, it defaults to the IRC; software can switch to crystal+PLL for 48 MHz operation or use IRC alone for low-power modes - providing flexibility for cost-sensitive or battery-operated designs.

How does the EM773FHN33,551 handle low-power operation in battery-backed meters?

The EM773FHN33,551 supports Deep power-down mode with typical current draw below 10 µA. Entry requires pulling PIO1_4/WAKEUP HIGH and asserting Deep power-down control bits; exit is triggered by a ≥50 ns LOW pulse on the same pin. This enables ultra-low standby consumption in portable loggers or energy-harvesting meters while retaining full metrology state upon wake-up.