71M6521DE/71M6521FE
Energy Meter IC
DATASHEET
JANUARY 2008
List of Figures
Figure 1: IC Functional Block Diagram...........................................................................................................................8
Figure 2: General Topology of a Chopped Amplifier ....................................................................................................11
Figure 3: AFE Block Diagram.......................................................................................................................................12
Figure 4: Samples from Multiplexer Cycle....................................................................................................................15
Figure 5: Accumulation Interval....................................................................................................................................15
Figure 6: Interrupt Structure.........................................................................................................................................36
Figure 7: Optical Interface...........................................................................................................................................39
Figure 8: Connecting an External Load to DIO Pins.....................................................................................................41
Figure 9: 3-Wire Interface. Write Command, HiZ=0.....................................................................................................43
Figure 10: 3-Wire Interface. Write Command, HiZ=1...................................................................................................44
Figure 11: 3-Wire Interface. Read Command...............................................................................................................44
Figure 12: 3-Wire Interface. Write Command when CNT=0.........................................................................................44
Figure 13: 3-Wire Interface. Write Command when HiZ=1 and WFR=1.......................................................................44
Figure 14: Functions defined by V1..............................................................................................................................45
Figure 15: Voltage. Current, Momentary and Accumulated Energy .............................................................................47
Figure 16: Timing Relationship between ADC MUX, Compute Engine, and Serial Transfers. .....................................48
Figure 17: RTM Output Format....................................................................................................................................49
Figure 18: Operation Modes State Diagram.................................................................................................................51
Figure 19: Functional Blocks in BROWNOUT Mode (inactive blocks grayed out)........................................................52
Figure 20: Functional Blocks in LCD Mode (inactive blocks grayed out)......................................................................53
Figure 21: Functional Blocks in SLEEP Mode (inactive blocks grayed out) .................................................................54
Figure 22: Transition from BROWNOUT to MISSION Mode when System Power Returns.........................................55
Figure 23: Power-Up Timing with V3P3SYS and VBAT tied together ..........................................................................55
Figure 24: Power-Up Timing with VBAT only ...............................................................................................................56
Figure 25: Wake Up Timing..........................................................................................................................................57
Figure 26: MPU/CE Data Flow.....................................................................................................................................58
Figure 27: MPU/CE Communication ............................................................................................................................58
Figure 28: Resistive Voltage Divider (Left), Current Transformer (Right).....................................................................59
Figure 29: Resistive Shunt ...........................................................................................................................................59
Figure 30: Crystal Frequency over Temperature..........................................................................................................61
Figure 31: Crystal Compensation.................................................................................................................................62
Figure 32: Connecting LCDs........................................................................................................................................63
Figure 33: I2C EEPROM Connection............................................................................................................................65
Figure 34: Three-Wire EEPROM Connection...............................................................................................................66
Figure 35: Connections for the RX Pin.........................................................................................................................66
Figure 36: Connection for Optical Components ...........................................................................................................67
Figure 37: Voltage Divider for V1 .................................................................................................................................68
Figure 38: External Components for the RESET Pin: Push-Button (Left), Production Circuit (Right)...........................68
Figure 39: External Components for the Emulator Interface ........................................................................................69
Figure 40: Wh Accuracy, 0.1A to 200A at 240V/50Hz and Room Temperature...........................................................93
Figure 41: Meter Accuracy over Harmonics at 240V, 30A............................................................................................93
Figure 42: Typical Meter Accuracy over Temperature Relative to 25°C.......................................................................94
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