EM773設計的8（16）位智能電表技術

本文介紹了EM773主要特性和優(yōu)勢，方框圖，智能電表原理方框圖，電表主要元件BOM以及智能電表無線插頭電表電路圖和電表指標。

NXP 公司的EM773是基于ARM Cortex-M0的低功耗32位智能電表集成電路，CPU頻率高達48MHz，具有豐富外設包括多達32KB標閃存，多達8KB數(shù)據(jù)存儲器，一個Fast-mode PlusI2C總線接口，一個RS-485/EIA-485 UART，一個帶SSP特性的SPI接口，三個通用計數(shù)器/定時器，多達25個GPIO，以及用于電能測量的測量引擎。

EM773主要特性和優(yōu)勢：

System:

ARM Cortex-M0 processor, running at frequencies of up to 48 MHz.

ARM Cortex-M0 built-in Nested Vectored Interrupt Controller (NVIC).

Serial Wire Debug.

System tick timer.

Memory:

32 kB on-chip flash programming memory.

8 kB SRAM.

In-System Programming (ISP) and In-Application Programming (IAP) via on-chip bootloader software.

Digital peripherals:

Up to 25 General Purpose I/O (GPIO) pins with configurable pull-up/pull-down resistors.

GPIO pins can be used as edge and level sensitive interrupt sources.

High-current output driver (20 mA) on one pin.

High-current sink drivers (20 mA) on two I2C-bus pins in Fast-mode Plus.

Three general purpose counter/timers with a total of two capture inputs and 10 match outputs.

Programmable WatchDog Timer (WDT).

Analog peripherals:

Metrology Engine for Smart Metering with two current inputs and a voltage input.

Serial interfaces:

UART with fractional baud rate generation, internal FIFO, and RS-485 support.

One SPI controller with SSP features and with FIFO and multi-protocol capabilities.

I2C-bus interface supporting full I2C-bus specification and Fast-mode Plus with a data rate of 1 Mbit/s with multiple address recognition and monitor mode.

Clock generation:

12 MHz internal RC oscillator trimmed to 1 % accuracy that can optionally be used as a system clock.

Crystal oscillator with an operating range of 1 MHz to 25 MHz.

Programmable watchdog oscillator with a frequency range of 7.8 kHz to 1.8 MHz.

PLL allows CPU operation up to the maximum CPU rate without the need for a high-frequency crystal. May be run from the system oscillator or the internal RC oscillator.

Clock output function with divider that can reflect the system oscillator clock, IRC clock, CPU clock, and the Watchdog clock.

Power control:

Integrated PMU (Power Management Unit) to minimize power consumption during Sleep, Deep-sleep, and Deep power-down modes.

Three reduced power modes: Sleep, Deep-sleep, and Deep power-down.

Processor wake-up from Deep-sleep mode via a dedicated start logic using up to 13 of the functional pins.

Power-On Reset (POR).

Brownout detect with four separate thresholds for interrupt and forced reset.

Unique device serial number for identification.

Single 3.3 V power supply (1.8 V to 3.6 V).

Available as 33-pin HVQFN package.

EM773應用：

Smart Metering

圖1。EM773方框圖

圖2。EM773智能電表原理方框圖

圖3。EM773 CGU方框圖

圖4。EM773電表主要元件BOM

圖5。EM773插頭式電表外形圖

圖6。EM773智能電表無線插頭電表電路圖
無線插頭電表指標：