Rainbow Electronics 78M6631 User Manual

78M6631

3-Phase Power

-

Measurement IC

Teridian is a trademark and Single Converter Technology is a registered trademark of Max im Integr ated Products, Inc.

19-6039; Rev 1; 1/12

DATA SHEET

DS_6631_056

DESCRIPTION

The Teridian™ 78M6631 is a highly integrated 3-phase
power measurement and monitoring system-on-chip
(SoC), with a 10 MHz 8051-compatible MPU core and
Single Converter Technology® containing a 22-bit delta­sigma converter and 32-bit compute engine (CE). The
78M6631 has been designed specifically for a wide
variety of applications requiring 3-phase power and
quality measurements. It supports both Delta and Wye
configurations.

At the measurement interface, the device provides six
analog inputs including three differential current and three
voltage for interfacing to current and voltage sensors. The
device provides better than 0.5% accuracy over a wide
2000:1 dynamic range.

The integrated MPU core and 128 KB of flash memory
provide a flexible means of configuration, post­processing, data formatting, interfacing to host processor
via a UART or SPI interface, or using DIO pins for LEDs
or relay control. Complete firmware is available from
Maxim and can be loaded into the IC during
manufacturing test.

FE ATURES

• < 0.5% W att Accuracy Over 2000:1 Current

Range and Over Temperature

• Exceeds IEC 62053/ANSI C12.20 Standards

• Voltage Reference < 40 ppm/°C

• Six Analog Inputs Supporting 3-Phase Voltage

and Current Measurement Inputs

• Pin- or Biselectable Delta or Wye Configuration

• 22-Bit Delta-Sigma ADC with Independent 32-

Bit Compute Engine (CE)

• 8-Bit MPU (80515), One Clock Cycle per

Instruction with 4 KB MPU XRAM

• 128 KB Flash with Security

• 32 kHz Time Base with Hardware Watchdog

Tim er

• UART, I

Interface Options

• 17 General-Purpose 5 V Tolerant I/O Pins

• Packaged in a RoHS-Compliant (6/6)

Lead(Pb)-Free 56-Pin TQFN

• Application Firmware Includes (per Phase):

o True RMS Current and Voltage Calculations
o Active, Reactive, Apparent, Fundamental,

o Fundamental and Harmonic Current and

o Line Frequency and Power Factor

o Phase Compensation (±18° at 60 Hz)
o Built-In Calibration Routines
o Programmable Alarm Thresholds
o Command Line (UART) Communications
o High-Speed SPI Communications

2

C, and High-Speed Slave SPI Host

and Harmonic Power Calculations

Voltage Calculations

Calculations

Rev 1 1

78M6631 Data Sheet DS_6631_056

Table of Contents

1 Hardware Functional Description ................................................................................................. 5

1.1 Hardware Overview................................................................................................................. 5

1.2 Device Reset .......................................................................................................................... 7

1.3 Power Management ................................................................................................................ 7

1.3.1 Voltage Regulator........................................................................................................ 7

1.3.2 Power Fault Management ............................................................................................ 7

1.4 Analog Front-End (AFE) .......................................................................................................... 8

1.4.1 Analog Current and Voltage Inputs .............................................................................. 8

1.5 Digital Computation Engine (CE) ............................................................................................. 9

1.6 80515 MPU Core .................................................................................................................. 10

1.6.1 SFRs ......................................................................................................................... 10

1.7 RAM ..................................................................................................................................... 10

1.8 IORAM .................................................................................................................................. 10

1.9 Flash..................................................................................................................................... 10

1.9.1 Program Security....................................................................................................... 10

1.10 Oscillator............................................................................................................................... 11

1.11 PLL and Internal Clock Generation ........................................................................................ 11

1.12 Real-Time Clock (RTC) ......................................................................................................... 11

1.13 Hardware Watchdog Timer.................................................................................................... 11

1.14 Temperature Sensor ............................................................................................................. 12

1.15 General Purpose Digital I/O ................................................................................................... 12

1.16 D/Y Selection Pin .................................................................................................................. 12

1.17 EEPROM Interface................................................................................................................ 12

1.18 SPI Slave Port ...................................................................................................................... 12

1.19 Test Port ............................................................................................................................... 13

1.20 UART .................................................................................................................................... 13

1.21 In Circuit Emulator (ICE) Port ................................................................................................ 14

2 Electrical Specifications .............................................................................................................. 15

2.1 Absolute Maximum Ratings ................................................................................................... 15

2.2 Recommended External Components ................................................................................... 16

2.3 Recommended Operating Conditions .................................................................................... 16

2.4 Performance Specifications ................................................................................................... 17

2.4.1 Input Logic Levels ..................................................................................................... 17

2.4.2 Output Logic Levels ................................................................................................... 17

2.4.3 Power-Fault Comparator ........................................................................................... 17

2.4.4 Power Supply Monitor ............................................................................................... 18

2.4.5 Supply Current .......................................................................................................... 18

2.4.6 Crystal Oscillator ....................................................................................................... 18

2.4.7 Temperature Sensor.................................................................................................. 19

2.4.8 VREF ........................................................................................................................ 19

2.4.9 ADC Converter, V3P3A Referenced .......................................................................... 20

2.5 Timing Specifications ............................................................................................................ 21

2.5.1 Flash Memory ........................................................................................................... 21

2.5.2 EEPROM Interface .................................................................................................... 21

2.5.3 RESET ...................................................................................................................... 21

2.5.4 SPI Slave Port ........................................................................................................... 22

3 Packaging .................................................................................................................................... 23

3.1 56-Pin QFN Package ............................................................................................................ 23

3.2 Pinout ................................................................................................................................... 23

3.2.1 56-Pin QFN Package Outline ..................................................................................... 24

3.2.2 Recommended PCB Land Pattern for the QFN-56 Package ...................................... 25

4 Pin Descriptions .......................................................................................................................... 26

2 Rev 1

DS_6631_056 78M6631 Data Sheet

4.1 Power and Ground Pins ........................................................................................................ 26

4.2 Analog Pins........................................................................................................................... 26

4.3 Digital Pins ............................................................................................................................ 27

5 I/O Equivalent Circuits ................................................................................................................. 28

6 Ordering Information ................................................................................................................... 29

7 Contact Information ..................................................................................................................... 29

Revision History .................................................................................................................................. 30

Rev 1 3

78M6631 Data Sheet DS_6631_056

Figures

Figure 1: 78M6631 IC Functional Block Diagram ..................................................................................... 6

Figure 2: AFE Block Diagram ................................................................................................................... 8

Figure 3: Functions Defined by V1 ......................................................................................................... 11

Figure 4: SPI Slave Port: Typical Read and Write Operations ................................................................ 13

Figure 5: SPI Slave Port Timing ............................................................................................................. 22

Figure 6: Pinout for QFN-56 Package .................................................................................................... 23

Figure 7: PCB Land Pattern for QFN-56 Package .................................................................................. 25

Figure 8: I/O Equivalent Circuits............................................................................................................. 28

Tables

Table 1: SPI Command Description ....................................................................................................... 13

Table 2: Absolute Maximum Ratings ...................................................................................................... 15

Table 3: Recommended External Components ...................................................................................... 16

Table 4: Recommended Operating Conditions ....................................................................................... 16

Table 5: Input Logic Levels .................................................................................................................... 17

Table 6: Output Logic Levels ................................................................................................................. 17

Table 7: Power-Fault Comparator Performance Specifications ............................................................... 17

Table 8: Power Supply Monitor Performance Specifications (BME= 1).................................................... 18

Table 9: Supply Current Performance Specifications .............................................................................. 18

Table 10: Crystal Oscillator Performance Specifications ......................................................................... 18

Table 11: Temperature Sensor Performance Specifications ................................................................... 19

Table 12: VREF Performance Specifications .......................................................................................... 19

Table 13: ADC Converter Performance Specifications ........................................................................... 20

Table 14: Flash Memory Timing Specifications ...................................................................................... 21

Table 15: EEPROM Interface Timing ..................................................................................................... 21

Table 16: RESET Timing ....................................................................................................................... 21

Table 17: SPI Slave Port Timing ............................................................................................................ 22

Table 19: Power and Ground Pins ......................................................................................................... 26

Table 20: Analog Pins............................................................................................................................ 26

Table 21: Digital Pins ............................................................................................................................. 27

Table 22: Ordering Information .............................................................................................................. 29

4 Rev 1

DS_6631_056 78M6631 Data Sheet

1 Hardware Functional Description

1.1 Hardware Overview

The Teridian 78M6631 single-chip power measurement and monitoring device integrates all the primary
AC measurement and control blocks required to implement the 3-phase power measurement and
monitoring system.

The 78M6631 includes:

• Six input analog front-end (AFE) (3 Differential Current/3 Voltage)

• Independent digital computation engine (CE)

• 8051-compatible microprocessor (MPU) which executes one instruction per clock cycle (80515)

• Precision voltage reference

• Temperature sensor

• RAM and flash memory

• A variety of I/O pins

• Communication Interfaces: UART, SPI, and I

Various current sensor technologies are supported including Current Transformers (CT), Resistive
Shunts, and Rogowski coils.

The 32-bit compute engine (CE) of the 78M6631 sequentially process the samples from the analog inputs
on pins IA, IB, IC, VA, VB, and VC and performs calculations to measure active power (Watts), reactive
power (VARs), apparent power (VAs), power factor, fundamental power, and harmonic power for three
independent phases. RMS, fundamental, and harmonic currents and voltages are also computed for each
phase. Totals are available for most results.

Figure 1 provides a block diagram of the 78M6631 IC. A detailed description of the various functional

blocks follows.

Refer to the applicable Firmware Description Document for additional supported functionality.

2

C (Master)

Rev 1 5

78M6631 Data Sheet DS_6631_056

∆Σ ADC

CONVERTER

VREF

MUXP

XIN

XOUT

VREF

RESET

V1

UART

TX

RX

DIGITAL I/O

POWER FAULT

GNDD

V3P3A

V3P3D

VOLT

REG

2.5V to Logic

TMUXOUT

FAULTZ

GNDA

VBIAS

TEMP

OSC

(32.768kHz)

MCK

PLL

VREF

CKTEST

TEST
MODE

E_ RXTX

RTC

VBIAS

ICE_E

TEST

MUX

V3P3D

CE_PROG

CK_CE

CK_MPU

80MHz

VADC

CE

MULTI-

PURPOSE

IO

RTM

RPULSE

WPULSE

DIO_4...

to TMUX

SPI SLAVE

EEPROM I/F

FLASH
128KB

XRAM

4kB

CE_DATA

PCSZ
PCLK

PSDI

PSDO

SDATA

SDCK

SFR

80515

MPU

EMULATOR

E_ TCLK

E_ RSTZ

E_ RXTX

E_ TCLK

E_RST

RPULSE

WPULSE

XRAM BUS

8

16

32

CKTEST

ICE_E

CKTESTI

PCLK

PSDO

PCSZ

PSDI

FIR

VB

VC

VA

XPULSE

YPULSE

XPULSE

YPULSE

IBN

ICP

ICN

IBP

IAP

IAN

DIO3
DIO4/SDCK
DIO5/SDATA
DIO6
DIO8
DIO9
D/Y
DIO11

DIO17

DIO24
DIO25

DIO45
DIO47

V3P3SYS

VBAT

DIO51
DIO53

DIO30

DIO55

DIO29

Figure 1: 78M6631 IC Functional Block Diagram

6 Rev 1

DS_6631_056 78M6631 Data Sheet

1.2 Device Reset

When the RESET pin is pulled high, all digital activity stops. Only the oscillator and RTC module continue
to run. Additionally, all IORAM bits are set to their default states. As long as V1 (the input voltage at the
power fault block) is greater than VBIAS, the internal 2.5 V regulator continues to provide power to the
digital section.

Once initiated, the reset mode persists until the reset timer times out. This occurs in 4096 cycles of the
crystal clock after RESET goes low, at which time the MPU begins executing its preboot and boot
sequences from address 0x0000.

1.3 Power Management

1.3.1 Voltage Regulator

The 78M6631 provides an on-chip voltage regulator to create a 2.5 V supply for the digital logic. This
regulator can be run off of the V3P3SYS or VBAT inputs depending upon power availability.

1.3.2 Power Fault Management

The 78M6631 provides for both hardware and software controlled power fault management. The V1 pin is
connected to a comparator to monitor system power fault conditions. When the input to the comparator
falls (V1 < VBIAS) the device can enter a BROWNOUT mode, if supported in firmware and there is
sufficient voltage on VBAT, that reduces the MPU rate to 32 kHz and disables all the measurement front­end circuits. If the overhead on VBAT is insufficient to maintain a BROWNOUT mode, then the device can
also attempt to enter a SLEEP mode where only RTC functions are active.

If there is not sufficient voltage on VBAT (or it is not supported), then the part enters RESET mode when
the comparator fails.

Rev 1 7

78M6631 Data Sheet DS_6631_056

VA

VB

MUX

VREF

4.9152 MHz

VBIAS

CROSS

CK32

VREF

MUX

CTRL

VC

MUX

V3P3A

FIR

VBIAS

∆Σ ADC

CONVERTER

+

-

VREF

TEMP

V3P3D

FIR_DONE

FIR_START

IBP
IBN
ICP
ICN

IAP
IAN

-

+

-

+

-

+

1.4 Analog Front-End (AFE)

The AFE functions as a data acquisition system, controlled by the MPU. The main blocks in the AFE
consist of an input multiplexer, a delta-sigma A/D converter, a FIR decimation filter and a voltage
reference. The metrology input signals (IAP, IAN, IBP, IBN, ICP, ICN, VA, VB, VC, and TEMP) are
multiplexed before being sampled by the ADC. The ADC output is decimated by the FIR filter and the
results are stored in RAM where they can be accessed by the CE and the MPU.

The functionality of the AFE is established for various system requirements with different CE code. AFE
programmability includes, but is not limited to:

• Input multiplexer settings

• Voltage supply and temperature monitor inputs

• ADC sampling rate

• FIR length/resolution

Figure 2: AFE Block Diagram

1.4.1 Analog Current and Voltage Inputs

With all CE code implementations for the 78M6631, pins IAP, IAN, IBP, IBN, ICP, ICN, VA, VB, and VC
are analog inputs to the AFE for measuring current and voltage. Various current sensor technologies can
be supported including Current Transformers, Resistive Shunts, and Rogowski coils.

8 Rev 1

DS_6631_056 78M6631 Data Sheet

1.5 Digital Computation Engine (CE)

The CE, a dedicated 32-bit digital signal processor, performs the back-end computations. CE calculations
include:

• Gain and offset compensation

• Delay compensation on all channels

• 90° phase shift for VAR calculations

• Frequency measurement

• Accumulation for voltage and current RMS and power computation

• Active, reactive, apparent, fundamental, and harmonic power calculation

• Fundamental and harmonic current and voltage calculations

• Monitoring of the input signal frequency (for frequency and phase information)

• Monitoring of the input signal amplitude (for sag detection)

• Temperature acquisition

Due to the custom nature and complexity of the CE, the CE code is part of the installed firmware and
is not modified by the user. Contact Maxim support for more information regarding CE code.

Rev 1 9