MAXIM 78M6612

19-5348; Rev 2; 1/12
78M6612
Single-Phase, Dual-Outlet
Power and Energy Measurement IC
DATA SHEET
DS_6612_001
FEATURES
DESCRIPTION
The Teridian™ 78M6612 is a highly integrated, single-phase,
power and energy measurement and monitoring system-onchip (SoC) that includes a 32-bit compute engine (CE), an
MPU core, RTC, and flash. Our Single Converter
Technology® with a 22-bit delta-sigma ADC, four analog
inputs, digital temperature compensation, and precision
voltage reference supports a wide range of single-phase,
dual-outlet power measurement applications with very few
external components.
With measurement technology leveraged from Maxim’s flagship
utility metering ICs, the device offers features including 32 KB
of flash program memory, 2 KB shared RAM, three low-power
modes with internal timer or external event wake-up, two
UARTs, I2C/MICROWIRE® EEPROM I/F, and an in-system
programmable flash. Complete outlet measurement unit (OMU)
and AC power monitor (AC-PMON) firmware is available or can
be preloaded into the IC.
A complete array of ICE and development tools, programming
libraries and reference designs enable rapid development and
certification of power and energy measurement solutions that
meet the most demanding worldwide electricity metering
standards.
CT
LIVE
OUTLET
POWER SUPPLY
NEUT
CONVERTER
IA
V3.3A
V3.3
SYS
VA
IB
VB
TERIDIAN
78M6612
GNDA GNDD
PWR MODE
CONTROL
REGULATOR
VBAT
V2.5
VOLTAGE REF
VREF
VBIAS
TEMP
SENSOR
RAM
SERIAL PORTS
TX0
FLASH
RX0
RX1
COMPUTE
ENGINE
TX1
POWER
FAULT
32 kHz
COMPARATOR
V1
OSC/PLL
XIN
XOUT
MPU
OPTIONAL
WAKE-UP
BATTERY
DIO, PULSE
COM0..3
SEG0..18
SEG 24..31/
DIO 4..11
SEG 34..37/
DIO 14..17
OPTIONAL
2
I C or µWire
EEPROM
SEG 32,33,
38/ICE
RTC
TIMERS
ICE
ICE_E
V3P3D
GNDD
Teridian is a trademark and Single Converter Technology is a registered
trademark of Maxim Integrated Products, Inc.
MICROWIRE is a registered trademark of National Semiconductor Corp.
Rev 2
• Measures Each Outlet of a Duplex Receptacle with
a Single IC
• Provides Complete Energy Measurement and
Communication Protocol Capability in a Single IC
• Intelligent Switch Control Capability
• < 0.5% Wh Accuracy Over 2000:1 Current Range
and Over Temperature
• Exceeds IEC 62053/ANSIC12.20 Standards
• Voltage Reference < 40 ppm/°C
• Four Sensor Inputs – VDD Referenced
• Low Jitter Wh and VARh Pulse Test Outputs
(10 kHz max)
• Pulse Count for Pulse Outputs
• Line Frequency Count for RTC
• Digital Temperature Compensation
• Sag Detection for Phase A and B
• Independent 32-Bit Compute Engine
• 46-64 Hz Line Frequency Range with Same Calibration
• Phase Compensation (±7°)
• Battery Backup for RTC and Battery Monitor
• Three Battery Modes with Wake-Up Timer:
Brownout Mode (48 µA)
LCD Mode (5.7 µA)
Sleep Mode (2.9 µA)
• Energy Display on Main Power Failure
• Wake-Up Timer
• 22-Bit Delta-Sigma ADC
• 8-Bit MPU (80515), 1 Clock Cycle per Instruction
with Integrated ICE for MPU Debug
• RTC with Temperature Compensation
• Auto-Calibration
• Hardware watchdog Timer, Power-Fail Monitor
• LCD Driver (Up to 152 Pixels)
• Up to 18 General-Purpose I/O Pins
• 32 kHz Time Base
• 32 KB Flash with Security
• 2 KB MPU XRAM
• Two UARTs
• Digital I/O Pins Compatible with 5 V Inputs
• 64-Pin LQFP or 68-Pin QFN Package
• RoHS-Compliant (6/6) Lead(Pb)-Free Packages
• Complete Application Firmware Available
1
78M6612 Data Sheet
DS_6612_001
Table of Contents
1
Hardware Description .................................................................................................................... 7
1.1 Hardware Overview................................................................................................................. 7
1.2 Analog Front End (AFE) .......................................................................................................... 8
1.2.1 Input Multiplexer .......................................................................................................... 8
1.2.2 A/D Converter (ADC) ................................................................................................... 9
1.2.3 FIR Filter ..................................................................................................................... 9
1.2.4 Voltage References ..................................................................................................... 9
1.2.5 Temperature Sensor.................................................................................................... 9
1.2.6 Battery Monitor ............................................................................................................ 9
1.3 Digital Computation Engine (CE) ........................................................................................... 10
1.3.1 Real-Time Monitor ..................................................................................................... 10
1.3.2 Pulse Generator ........................................................................................................ 10
1.3.3 Data RAM (XRAM) .................................................................................................... 10
1.4 80515 MPU Core .................................................................................................................. 11
1.4.1 UARTs ...................................................................................................................... 11
1.5 On-Chip Resources............................................................................................................... 11
1.5.1 Oscillator ................................................................................................................... 11
1.5.2 PLL and Internal Clocks............................................................................................. 11
1.5.3 Real-Time Clock (RTC) ............................................................................................. 12
1.5.4 Temperature Sensor.................................................................................................. 12
1.5.5 Flash Memory ........................................................................................................... 12
1.5.6 Optical Interface ........................................................................................................ 13
1.5.7 Digital I/O .................................................................................................................. 13
1.5.8 LCD Drivers .............................................................................................................. 16
1.5.9 EEPROM Interface .................................................................................................... 16
1.5.10 Hardware Watchdog Timer ........................................................................................ 17
1.5.11 Test Ports (TXUXOUT pin) ........................................................................................ 17
2
Functional Description ................................................................................................................ 18
2.1 Theory of Operation .............................................................................................................. 18
2.2 Fault and Reset Behavior ...................................................................................................... 19
2.2.1 Reset Mode ............................................................................................................... 19
2.2.2 Power Fault Circuit .................................................................................................... 19
2.3 Data Flow ............................................................................................................................. 19
2.4 CE/MPU Communication ...................................................................................................... 20
3
Application Information ............................................................................................................... 21
3.1 Connection of Sensors (CT, Resistive Shunt) ........................................................................ 21
3.2 Connecting 5 V Devices ........................................................................................................ 22
3.3 Temperature Measurement ................................................................................................... 22
3.4 Temperature Compensation .................................................................................................. 22
3.5 Connecting LCDs .................................................................................................................. 23
2
3.6 Connecting I C EEPROMs .................................................................................................... 23
3.7 Connecting Three-Wire EEPROMs ....................................................................................... 24
3.8 UART0 (TX0/RX0) ................................................................................................................ 24
3.9 UART1 (TX1/RX1) ................................................................................................................ 25
3.10 Connecting V1 and Reset Pins .............................................................................................. 25
3.11 Connecting the Emulator Port Pins ........................................................................................ 26
3.12 Flash Programming ............................................................................................................... 26
3.13 MPU Firmware Library .......................................................................................................... 26
3.14 Crystal Oscillator ................................................................................................................... 26
3.15 Measurement Calibration ...................................................................................................... 27
4
Electrical Specifications .............................................................................................................. 28
4.1 Absolute Maximum Ratings ................................................................................................... 28
4.2 Recommended External Components ................................................................................... 29
2
Rev 2
DS_6612_001
4.3
4.4
4.5
78M6612 Data Sheet
Recommended Operating Conditions .................................................................................... 29
Performance Specifications ................................................................................................... 30
4.4.1 Input Logic Levels ..................................................................................................... 30
4.4.2 Output Logic Levels................................................................................................... 30
4.4.3 Power-Fault Comparator ........................................................................................... 30
4.4.4 Battery Monitor .......................................................................................................... 31
4.4.5 Supply Current .......................................................................................................... 31
4.4.6 V3P3D Switch ........................................................................................................... 31
4.4.7 2.5V Voltage Regulator ............................................................................................. 32
4.4.8 Low Power Voltage Regulator ................................................................................... 32
4.4.9 Crystal Oscillator ....................................................................................................... 32
4.4.10 VREF, VBIAS ............................................................................................................ 33
4.4.11 LCD Drivers .............................................................................................................. 33
4.4.12 ADC Converter, V3P3A Referenced .......................................................................... 34
4.4.13 UART1 Interface........................................................................................................ 34
4.4.14 Temperature Sensor.................................................................................................. 34
Timing Specifications ............................................................................................................ 35
4.5.1 RAM and Flash Memory ............................................................................................ 35
4.5.2 Flash Memory Timing ................................................................................................ 35
4.5.3 EEPROM Interface .................................................................................................... 35
4.5.4 RESET and V1 .......................................................................................................... 35
4.5.5 RTC .......................................................................................................................... 35
5
Packaging .................................................................................................................................... 36
5.1 64-Pin LQFP Package .......................................................................................................... 36
5.1.1 Pinout........................................................................................................................ 36
5.1.2 Package Outline (LQFP 64)....................................................................................... 37
5.1.3 Recommended PCB Land Pattern for the LQFP-64 Package..................................... 38
5.2 68-Pin QFN Package ............................................................................................................ 39
5.2.1 Pinout........................................................................................................................ 39
5.2.2 Package Outline ........................................................................................................ 40
5.2.3 Recommended PCB Land Pattern for the QFN-68 Package ...................................... 41
6
Pin Descriptions .......................................................................................................................... 42
6.1 Power/Ground Pins ............................................................................................................... 42
6.2 Analog Pins........................................................................................................................... 42
6.3 Digital Pins............................................................................................................................ 43
7
I/O Equivalent Circuits................................................................................................................. 44
8
Ordering Information ................................................................................................................... 45
9
Contact Information ..................................................................................................................... 45
Revision History .................................................................................................................................. 46
Rev 2
3
78M6612 Data Sheet
DS_6612_001
Figures
Figure 1: IC Functional Block Diagram ..................................................................................................... 6
Figure 2: AFE Block Diagram ................................................................................................................... 8
Figure 3: Connecting an External Load to DIO Pins ............................................................................... 15
Figure 4: Functions Defined by V1 ......................................................................................................... 17
Figure 5: Voltage, Current, Momentary and Accumulated Energy........................................................... 18
Figure 6: MPU/CE Data Flow ................................................................................................................. 19
Figure 7: MPU/CE Communication ........................................................................................................ 20
Figure 8: Resistive Voltage Divider ........................................................................................................ 21
Figure 9: Resistive Current Shunt .......................................................................................................... 21
Figure 10: Current Transformer.............................................................................................................. 21
Figure 11: Connecting LCDs .................................................................................................................. 23
Figure 12: I2C EEPROM Connection ...................................................................................................... 23
Figure 13: Three-Wire EEPROM Connection ......................................................................................... 24
Figure 14: Connections for the RX0 Pin ................................................................................................. 24
Figure 15: Voltage Divider for V1 ........................................................................................................... 25
Figure 16: External Components for RESET: Development Circuit (Left), Production Circuit (Right) ....... 25
Figure 17: External Components for the Emulator Interface.................................................................... 26
Figure 18: 64-Pin LQFP Pinout .............................................................................................................. 36
Figure 19: 68-Pin QFN Pinout ................................................................................................................ 39
4
Rev 2
DS_6612_001
78M6612 Data Sheet
Tables
Table 1: Inputs Selected in Regular and Alternate Multiplexer Cycles....................................................... 8
Table 2: Data/Direction Registers and Internal Resources for DIO Pin Groups ....................................... 14
Table 3: DIO_DIR Control Bit ................................................................................................................. 15
Table 4: Selectable Controls using the DIO_DIR Bits ............................................................................. 16
Table 5: Absolute Maximum Ratings ...................................................................................................... 28
Table 6: Recommended External Components ...................................................................................... 29
Table 7: Recommended Operation Conditions ....................................................................................... 29
Table 8: Input Logic Levels .................................................................................................................... 30
Table 9: Output Logic Levels ................................................................................................................. 30
Table 10: Power-Fault Comparator Performance Specifications ............................................................. 30
Table 11: Power-Fault Comparator Performance Specifications (BME=1) .............................................. 31
Table 12: Supply Current Performance Specifications ............................................................................ 31
Table 13: V3P3D Switch Performance Specifications ............................................................................. 31
Table 14: 2.5 V Voltage Regulator Performance Specifications .............................................................. 32
Table 15: Low-Power Voltage Regulator Performance Specifications ..................................................... 32
Table 16: Crystal Oscillator Performance Specifications......................................................................... 32
Table 17: VREF, VBIAS Performance Specifications.............................................................................. 33
Table 18: LCD Drivers Performance Specifications ................................................................................ 33
Table 19: ADC Converter Performance Specifications ........................................................................... 34
Table 20: UART1 Interface Performance Specifications ......................................................................... 34
Table 21: Temperature Sensor Performance Specifications ................................................................... 34
Table 22: RAM and Flash Memory Specifications .................................................................................. 35
Table 23: Flash Memory Timing Specifications ...................................................................................... 35
Table 24: EEPROM Interface Timing ..................................................................................................... 35
Table 25: RESET and V1 Timing ........................................................................................................... 35
Table 26: RTC Range ............................................................................................................................ 35
Table 27: Power/Ground Pins ................................................................................................................ 42
Table 28: Analog Pins............................................................................................................................ 42
Rev 2
5
78M6612 Data Sheet
DS_6612_001
IA
VA
IB
VB
∆Σ ADC
CONVERTER
VBAT
VREF
MUX
CTRL
EQU
MUX_ALT
CHOP_E
MUX_DIV
MCK
PLL
RTCLK (32KHz)
DIV
ADC
CK32
32KHz
CKOUT_E
CKADC
4.9MHz
CK_GEN
V2P5
V3P3D
CK_2X
MUX_SYNC
CKCE
<4.9MHz
WPULSE
VARPULSE
CE
MEMORY SHARE
1000-11FF
RX1 /
DIO1
TX1 /
DIO2 /
WPULSE /
VARPULSE
XFER BUSY
I/O RAM
CE_BUSY
EEPROM
INTERFACE
OPT_TXMOD
OPT_FDC
RTC
RTC_DEC_SEC
RTC_INC_SEC
CONFIG
SDIN
MPU
(80515)
OPTICAL
MOD
LCD_NUM
LCD_MODE
LCD_CLK
LCD_E
LCD_BLKMAP
LCD_SEG
LCD_Y
SDCK
SDOUT
UART
OPT_RXDIS
OPT_RXINV
OPT_TXE
OPT_TXINV
DATA
0000-FFFF
COM0..3
SEG0..18
SEG32,33
SEG19,38
DIO1,2
SEG24 / DIO4 ..
SEG31 / DIO11
SEG34 / DIO14 ..
SEG37 / DIO17,
SEG39 / DIO19,
SEG40 / DIO20
RTCLK
CONFIGURATION
PARAMETERS
(68 Pin Package Only)
2000-20FF
DIO3,
DIO21 / SEG41
0000-07FF
PROG
0000-7FFF
(SEG13 and SEG 14
on 68 Pin Package
Only)
DIGITAL I/O
DIO_EEX
DIO_PV/PW
DIO_DIR
DIO_R
LCD_NUM
DIO
WPULSE
VARPULSE
CKMPU
<4.9MHz
TX
VLC0
LCD DISPLAY
DRIVER
RTM_0..3
RTM_E
CE_E
PLS_INV
PLS_INTERVAL
PLS_MAXWIDTH
CE_LCTN
EQU
PRE_SAMPS
SUM_CYCLES
VLC1
MUX
DATA
00-7F
PROG
000-7FF
CE
CONTROL
VLC2
LCD_MODE
LCD_E
RTM
32 bit Compute
Engine
TEST
MODE
2.5V to logic
LCD_GEN
CE RAM
(0.5KB)
STRT
GNDD
CKFIR
4.9MHz
4.9MHz
RX
VBAT
LCD_ONLY
SLEEP
ECK_DIS
MPU_DIV
TEST
VBAT
FIR_LEN
VOLT
REG
XOUT
CKOUT_E
ADC_E
CK32
OSC
(32KHz)
XIN
FIR
VREF
VREF_CAL
VREF_DIS
CROSS
MUX
V3P3D
-
V3P3A
TEMP
V3P3D
VBIAS
VBIAS
MUX
+
CKTEST/
SEG19
V3P3SYS
GNDA
V3P3A
VREF
MEMORY
SHARE
CE_LCTN
MPU XRAM
(2KB)
00007FFF
FLASH
(32KB)
FLSH66ZT
VBIAS
V1
POWER FAULT
MPU_RSTZ
WAKE
EMULATOR
PORT
FAULTZ
E_RXTX
E_TCLK
E_RST (Open Drain)
COMP_STAT
RESET
E_RXTX/SEG38
E_TCLK/SEG33
E_RST/SEG32
TEST
MUX
TMUXOUT
TMUX[4:0]
ICE_E
Figure 1: IC Functional Block Diagram
6
Rev 2
DS_6612_001
78M6612 Data Sheet
1 Hardware Description
1.1
Hardware Overview
The Teridian 78M6612 single-chip measurement and monitoring IC integrates all the primary AC
measurement and control blocks required to implement a solid-state electricity Power and Energy
Measurement function. The 78M6618 includes:
•
A four-input analog front end (AFE)
•
•
•
•
An independent digital computation engine (CE)
An 8051-compatible microprocessor (MPU) which executes one instruction per clock cycle (80515)
A precision voltage reference
A temperature sensor
•
•
•
•
LCD drivers
RAM and Flash memory
A real time clock (RTC)
A variety of I/O pins
Various current sensor technologies are supported including Current Transformers (CT), and Resistive
Shunts.
In a typical application, the 32-bit compute engine (CE) of the 78M6612 sequentially processes the
samples from the analog inputs on pins IA, VA, IB, VB and performs calculations to measure active
2
2
energy (Wh), reactive energy (VARh), A h, and V h for four-quadrant measurement. These
measurements are then accessed by the MPU, processed further, and output using the peripheral
devices available to the MPU.
In addition to advanced measurement functions, the real time clock function allows the 78M6612 to
record time of use (TOU) measurement information for multi-rate applications and to time-stamp events.
Measurements can be displayed on 3.3 V LCDs if desired. Flexible mapping of LCD display segments
will facilitate utilization of existing custom LCDs. Design trade-off between number of LCD segments vs.
DIO pins can be implemented in software to accommodate various requirements.
In addition to the temperature-trimmed ultra-precision voltage reference, the on-chip digital temperature
compensation mechanism includes a temperature sensor and associated controls for correction of
unwanted temperature effects on measurement and RTC accuracy, e.g. to meet the requirements of
ANSI and IEC standards. Temperature-dependent external components such as crystal oscillator,
current transformers (CTs), and their corresponding signal conditioning circuits can be characterized and
their correction factors can be programmed to produce measurements with exceptional accuracy over the
industrial temperature range.
A block diagram of the IC is shown in Figure 1. A detailed description of various functional blocks follows.
Rev 2
7
78M6612 Data Sheet
1.2
DS_6612_001
Analog Front End (AFE)
The AFE functions as a data acquisition system, controlled by the MPU. It consists of an input
multiplexer, a delta-sigma A/D converter, and a voltage reference. The main signals (IA, VA, IB, VB) are
sampled and the ADC counts obtained are stored in CE DRAM where they can be accessed by the CE
and, if necessary, by the MPU.
VREF
IA
VA
IB
VB
∆Σ ADC
CONVERTER
VBIAS
VBIAS
MUX
VBAT
V3P3A
+
VREF
TEMP
MUX
CTRL
EQU
MUX_ALT
CHOP_E
MUX_DIV
VREF
VREF_CAL
VREF_DIS
MUX
FIR
ADC_E
FIR_LEN
CROSS
CK32
4.9MHz
FIR_DONE
FIR_START
Figure 2: AFE Block Diagram
1.2.1
Input Multiplexer
The input multiplexer supports up to four input signals that are applied to pins IA, VA, IB, and VB of the
device. Additionally, using the alternate multiplexer selection, it has the ability to select temperature and
the battery voltage. The multiplexer can be operated in two modes:
•
•
During a normal multiplexer cycle, the signals from the IA, IB, VA, and VB pins are selected.
During the alternate multiplexer cycle, the temperature signal (TEMP) and the battery monitor are
selected, along with the signal sources shown in Table 1. To prevent unnecessary drainage on the
battery, the battery monitor is enabled only with the BME bit (0x2020[6]) in the I/O RAM.
The alternate multiplexer cycles are usually performed infrequently (e.g. every second or so) by the MPU.
In order to prevent disruption of the voltage tracking PLL and voltage allpass networks, VA is not
replaced in the ALT mux selections. Table 1 details the regular and alternative multiplexer sequences.
Missing samples due to an ALT multiplexer sequence are filled in by the CE.
Table 1: Inputs Selected in Regular and Alternate Multiplexer Cycles
Regular MUX Sequence
ALT MUX Sequence
Mux State
Mux State
EQU
0
1
2
3
0
1
2
3
2
IA
VA
IB
VB
TEMP
VA
VBAT
VB
In a typical application, IA and IB are connected to current sensors that sense the current on each branch
of the line voltage. VA and VB are typically connected to voltage sensors through resistor dividers. The
multiplexer control circuit is clocked by CK32, the 32.768 kHz clock from the PLL block, and launches with
each new pass of the CE program. The duration of each multiplexer state depends on the number of
ADC samples processed by the FIR.
8
Rev 2
DS_6612_001
1.2.2
78M6612 Data Sheet
A/D Converter (ADC)
A single delta-sigma A/D converter digitizes the voltage and current inputs to the 78M6612. The
resolution of the ADC is configurable to either 21 or 22 bit. At the end of each ADC conversion, the FIR
filter output data is stored into the CE RAM location.
1.2.3
FIR Filter
The finite impulse response filter is an integral part of the ADC and it is optimized for use with the
multiplexer. The purpose of the FIR filter is to decimate the ADC output to the desired resolution. At the
end of each ADC conversion, the output data is stored into the CE RAM location determined by the
multiplexer selection. FIR data is stored LSB justified, but shifted left by nine bits.
1.2.4
Voltage References
The device includes an on-chip precision bandgap voltage reference that incorporates auto-zero
techniques. The reference is trimmed to minimize errors caused by component mismatch and drift. The
result is a voltage output with a predictable temperature coefficient.
1.2.5
Temperature Sensor
The 78M6612 includes an on-chip temperature sensor implemented as a bandgap reference. It is used
to determine the die temperature The MPU reads the temperature sensor output during alternate
multiplexer cycles. The primary use of the temperature data is to determine the magnitude of
compensation required to offset the thermal drift in the system (see Section 3.4 Temperature
Compensation).
1.2.6
Battery Monitor
The 78M6618 also has the ability to measure battery voltage by the ADC during alternative multiplexer
frames. When set, an on-chip 45 kΩ load resistor is applied to the battery and a scaled fraction of the
battery voltage is applied to the ADC input. Battery operating modes are not supported in all firmware
libraries. Contact Maxim support for more information.
Rev 2
9
78M6612 Data Sheet
1.3
DS_6612_001
Digital Computation Engine (CE)
The CE, a dedicated 32-bit signal processor, performs the precision computations necessary to
accurately measure energy. The CE calculations and processes include:
•
Multiplication of each current sample with its associated voltage sample to obtain the energy per
sample (when multiplied with the constant sample time).
•
Frequency-insensitive delay cancellation on all four channels (to compensate for the delay between
samples caused by the multiplexing scheme).
•
•
•
90° phase shifter (for narrowband VAR calculations).
Pulse generation.
Monitoring of the input signal frequency (for frequency and phase information).
•
•
Monitoring of the input signal amplitude (for sag detection).
Scaling of the processed samples based on calibration coefficients.
CE code is provided by Maxim as a part of the application firmware available. The CE is not
programmable by the user. Measurement algorithms in the CE code can be customized by Maxim
upon request.
The CE program resides in Flash memory. Allocated Flash space for the CE program cannot exceed
1024 words (2 KB). The CE can access up to 2 KB of data RAM (XRAM), or 512 32-bit data words. The
CE is also aided by support hardware to facilitate implementation of equations, pulse counters and
accumulators. Usage of this hardware is firmware specific.
1.3.1
Real-Time Monitor
The CE contains a Real-Time Monitor (RTM), which can be programmed to monitor four selectable CE
DRAM locations at full sample rate for system debug purposes. The four monitored locations can be serially
output to the TMUXOUT pin via the digital output multiplexer at the beginning of each CE code pass.
The RTM output is clocked by CKTEST.
1.3.2
Pulse Generator
The CE provides four pulse generators used to output CE status indicators (e.g. SAG) directly to
designated DIO pins.
1.3.3
Data RAM (XRAM)
The CE and MPU use a single general-purpose Data RAM (also referred to as XRAM). When the MPU
and CE are clocking at maximum frequency (10 MHz), the RAM may be accessed up to four times during
each 100 ns interval. These consist of two MPU accesses, one CE access and one SPI access.
10
Rev 2
DS_6612_001
1.4
78M6612 Data Sheet
80515 MPU Core
The 78M6612 includes an 80515 MPU (8-bit, 8051-compatible) that processes most instructions in one
clock cycle. Using a 5 MHz (4.9152 MHz) clock results in a processing throughput of 5 MIPS. The 80515
architecture eliminates redundant bus states and implements parallel execution of fetch and execution
phases. Normally a machine cycle is aligned with a memory fetch, therefore, most of the 1-byte
instructions are performed in a single machine cycle (MPU clock cycle). This leads to an 8x average
performance improvement (in terms of MIPS) over the Intel 8051 device running at the same clock
frequency. Actual processor clocking speed can be adjusted to the total processing demand of the
application (measurement calculations, memory management and I/O management).
Typical power and energy measurement functions based on the results provided by the internal
32-bit compute engine (CE) are available for the MPU as part of Maxim’s standard library. A
standard ANSI “C” 80515 application program library is available to help reduce design cycle.
1.4.1
UARTs
The 78M6612 includes two UARTs (UART0 and UART1) that can be programmed to communicate with a
variety of external devices. The UARTs are dedicated 2-wire serial interfaces, which can communicate at
rates up to 38,400 bits/s. All UART transfers are programmable for parity enable, parity, 2 stop bits/1
stop bit and XON/XOFF option for variable communication baud rates from 300 to 38,400 bps.
1.5
On-Chip Resources
1.5.1
Oscillator
The 78M6612 oscillator drives a standard 32.768 kHz watch crystal. These crystals are accurate and do
not require a high-current oscillator circuit. The 78M6612 oscillator has been designed specifically to
handle these crystals and is compatible with their high impedance and limited power handling capability.
1.5.2
PLL and Internal Clocks
Timing for the device is derived from the 32.768 kHz oscillator output. On-chip timing functions include:
•
•
The MPU master clock
A real time clock (RTC)
•
The delta-sigma sample clock.
The two general-purpose counter/timers are contained in the MPU.
The ADC master clock, CKADC, is generated by an on-chip PLL. It multiplies the oscillator output
frequency (CK32) by 150.
The CE clock frequency is always CK32 * 150, or 4.9152 MHz, where CK32 is the 32 kHz clock. The
-MPU_DIV
Hz where MPU_DIV
MPU clock frequency is determined by MPU_DIV and can be 4.9152 MHz *2
varies from 0 to 7 (MPU_DIV is 0 on power-up). This makes the MPU clock scalable from 4.9152 MHz
down to 38.4 kHz. The circuit also generates a 2x MPU clock for use by the emulator. This 2x MPU
clock is not generated when ECK_DIS is asserted by the MPU.
The setting of MPU_DIV is maintained when the device transitions to BROWNOUT mode, but the time
base in BROWNOUT mode is 28,672 Hz.
Rev 2
11
78M6612 Data Sheet
1.5.3
DS_6612_001
Real-Time Clock (RTC)
The RTC is driven directly by the crystal oscillator. The RTC consists of a counter chain and output
registers. The counter chain consists of seconds, minutes, hours, day of week, day of month, month, and
year. The RTC is not supported in all firmware libraries. Contact Maxim support for more information.
1.5.4
Temperature Sensor
The device includes an on-chip temperature sensor for determining the temperature of the bandgap
reference. The MPU may request an alternate multiplexer frame containing the temperature sensor
output by asserting MUX_ALT. The primary use of the temperature data is to determine the magnitude of
compensation required to offset the thermal drift in the system (see Section 3.4 Temperature
Compensation).
1.5.5
Flash Memory
The 78M6612 includes 32 KB of on-chip Flash memory. The Flash memory primarily contains MPU and
CE program code. It also contains images of the CE DRAM, MPU RAM, and I/O RAM. On power-up,
before enabling the CE, the MPU copies these images to their respective locations.
The Flash memory is segmented into individually erasable 1024-byte pages. Flash space allocated for the CE
program is limited to 1024 words (2 KB). The CE program must begin on a 1-KB boundary of the Flash address
space.
Flash Write Procedures
The MPU has the ability to write to the Flash memory when the CE is disabled. As an alternative to using Flash, a
small EEPROM can store data without compromises. EEPROM interfaces are included in the device.
Updating Individual Bytes in Flash Memory
The original state of a Flash byte is 0xFF (all ones). Once a value other than 0xFF is written to a Flash memory cell,
overwriting with a different value usually requires that the cell be erased first. Since cells cannot be erased
individually, the page has to be copied to RAM, followed by a page erase. After this, the page can be updated in
RAM and then written back to the Flash memory.
Flash Erase Procedures
Flash erasure is initiated by writing a specific data pattern to specific SFR registers in the proper sequence. These special
pattern/sequence requirements prevent inadvertent erasure of the Flash memory.
The mass erase sequence is:
1. Write 1 to the FLSH_MEEN bit (SFR address 0xB2[1].
2. Write pattern 0xAA to FLSH_ERASE (SFR address 0x94).
The mass erase cycle can only be initiated when the ICE port is enabled.
The page erase sequence is:
1. Write the page address to FLSH_PGADR (SFR address 0xB7[7:1].
2. Write pattern 0x55 to FLSH_ERASE (SFR address 0x94).
12
Rev 2
DS_6612_001
1.5.6
78M6612 Data Sheet
Optical Interface
The device includes an interface to implement an IR/optical port on UART1. The pin TX1 is designed to
directly drive an external LED for transmitting data on an optical link. The pin RX1 is designed to sense
the input from an external photo detector used as the receiver for the optical link. The IR/optical interface
is not supported in all firmware libraries. Contact Maxim support for more information.
1.5.7
Digital I/O
The device includes up to 18 pins (QFN 68 package) or 16 pins (LQFP 64 package) of general purpose
digital I/O. These pins are compatible with 5V inputs (no current-limiting resistors are needed). Some of
them are dedicated DIO (DIO3), some are dual-function that can alternatively be used as LCD drivers
(DIO4-11, 14-17, 19-21) and some share functions with the optical port (DIO1, DIO2). On reset or
power-up, all DIO pins are inputs until they are configured for the desired direction under MPU control.
The pins are configured by the DIO registers and by the five bits of the LCD_NUM register (located in I/O
RAM). Once declared as DIO, each pin can be configured independently as an input or output with the
DIO_DIRn bits. A 3-bit configuration word, DIO_Rx, can be used for certain pins, when configured as
DIO, to individually assign an internal resource such as an interrupt or a timer control. Table 2 lists the
direction registers and configurability associated with each group of DIO pins. Table 3 shows the configuration for a DIO pin through its associated bit in its DIO_DIR register.
Tables showing the relationship between LCD_NUM and the available segment/DIO pins can be found in
Section 3.5 Connecting LCDs and in Section 4.3 I/O Description under LCD_NUM[4:0].
Rev 2
13
78M6612 Data Sheet
DS_6612_001
Table 2: Data/Direction Registers and Internal Resources for DIO Pin Groups
DIO
Pin no. (64 LQFP)
Pin no. (68 QFN)
Data Register
Direction Register
1
2
3
4
5
6
7
8
9
1
0
1
1
1
2
1
3
1
4
1
5
–
5
7
3
–
3
6
3
7
3
8
3
9
4
0
4
1
4
2
4
3
–
–
2
0
2
1
–
6
0
3
5
3
9
4
0
4
1
4
2
4
3
4
4
4
5
4
6
–
–
2
1
2
2
–
1
2
3
4
5
6
7
0
1
2
3
–
–
6
7
6
7
–
–
DIO1=P1 (SFR 0x90)
–
–
1
2
3
4
5
6
7
–
DIO
Y
Y
Y
Y
Y
Y
16
1
7
1
8
1
9
2
0
2
1
2
2
2
3
Pin no. (64 LQFP)
22
1
2
–
2
3
4
4
–
–
–
Pin no. (68 QFN)
23
1
3
–
2
4
4
7
6
8
0
1
–
3
4
5
–
–
–
–
–
–
Internal Resources
Configurable
1
2
3
–
–
DIO_DIR1 (SFR 0x91)
Y
Direction Register
0
–
Internal Resources
Configurable
Data Register
14
x
Y
Y
Y
Y
–
–
DIO2=P2 (SFR 0xA0)
0
1
–
3
4
5
DIO_DIR2 (SFR 0xA1)
N
N
–
N
N
N
Rev 2
DS_6612_001
78M6612 Data Sheet
Table 3: DIO_DIR Control Bit
DIO_DIR [n]
DIO Pin n Function
0
1
Input
Output
Additionally, if DIO6 and DIO7 are declared outputs, they can be configured as dedicated pulse outputs
(WPULSE = DIO6, VARPULSE = DIO7) using DIO_PW and DIO_PV registers. In this case, DIO6 and
DIO7 are under CE control. DIO4 and DIO5 can be configured to implement the EEPROM Interface.
If the optical UART is not used, TX1 and RX1 can be configured as dedicated DIO pins (DIO1, DIO2, see
Section 1.5.6 Optical Interface).
A 3-bit configuration word, I/O RAM register, DIO_Rx (0x2009[2:0] through 0x200E[6:4]) can be used for
certain pins, when configured as DIO, to individually assign an internal resource such as an interrupt or a
timer control (see Table 2 for DIO pins available for this option). This way, DIO pins can be tracked even
if they are configured as outputs.
Tracking DIO pins configured as outputs is useful for pulse counting without external
hardware.
When driving LEDs, relay coils etc., the DIO pins should sink the current into ground (as
shown in Figure 3, right), not source it from V3P3D (as shown in Figure 3, left). This is due
to the resistance of the internal switch that connects V3P3D to either V3P3SYS or VBAT.
When configured as inputs, the dual-function (DIO/SEG) pins should not be pulled above
V3P3SYS in MISSION and above VBAT in LCD and BROWNOUT modes. Doing so will
distort the LCD waveforms of the other pins. This limitation applies to any pin that can be
configured as a LCD driver.
The control resources selectable for the DIO pins are listed in Table 4. If more than one input is
connected to the same resource, the resources are combined using a logical OR.
78M6612
V3P3SYS
VBA
VBAT
T
V3P3
V3P3D
D
DIO
DIO1
1
78M6612
3.3V
R
VBA
T
V3P3D
V3P3
D
DIO
DIO1
1
LED
LE
D
DGND
DGN
D
Not recommended
3.3V
V3P3SYS
LED
LE
D
R
DGND
DGN
D
Recommended
Figure 3: Connecting an External Load to DIO Pins
Rev 2
15
78M6612 Data Sheet
DS_6612_001
Table 4: Selectable Controls using the DIO_DIR Bits
DIO_R Value
1.5.8
Resource Selected for DIO Pin
0
NONE
1
Reserved
2
T0 (counter0 clock)
3
T1 (counter1 clock)
4
High priority I/O interrupt (INT0 rising)
5
Low priority I/O interrupt (INT1 rising)
6
High priority I/O interrupt (INT0 falling)
7
Low priority I/O interrupt (INT1 falling)
LCD Drivers
The device in the 68-pin QFN package contains 20 dedicated LCD segment drivers in addition to the 18
multi-use pins described above. Thus, the device is capable of driving between 80 to 152 pixels of LCD
display with 25% duty cycle (or 60 to 114 pixels with 33% duty cycle). At eight pixels per digit, this
corresponds to 10 to 19 digits.
The device in the 64-pin LQFP package contains 18 dedicated LCD segment drivers in addition to the 17
multi-use pins described above. Thus, the device is capable of driving between 72 to 140 pixels of LCD
display with 25% duty cycle (or 60 to 105 pixels with 33% duty cycle). At eight pixels per digit, this
corresponds to 9 to 17 digits.
The LCD drivers are grouped into four commons and up to 38 segment drivers (68-pin package), or 4
commons and 35 segment drivers (64-pin package). The LCD interface is flexible and can drive either
digit segments or enunciator symbols.
Segment drivers SEG18 and SEG19 can be configured to blink at either 0.5 Hz or 1 Hz. The blink rate is
controlled by LCD_Y. There can be up to four pixels/segments connected to each of these drivers.
LCD_BLKMAP18[3:0] and LCD_BLKMAP19[3:0] identify which pixels, if any, are to blink.
LCD interface memory is powered by the non-volatile supply. The bits of the LCD memory
are preserved in LCD and SLEEP modes, even if their pin is not configured as SEG. In this
case, they can be useful as general- purpose non-volatile storage.
1.5.9
EEPROM Interface
The 78M6612 provides hardware support for an optional two-pin or a three-wire (µ-wire) EEPROM
interface.
Two-Pin EEPROM Interface
The dedicated 2-pin serial interface communicates with external EEPROM devices. The interface is
multiplexed onto the DIO4 (SCK) and DIO5 (SDA) pins.
Three-Wire (µ-Wire) EEPROM Interface
A 500 kHz 3-wire interface, using SDATA, SCK, and a DIO pin for CS is also available.
16
Rev 2
DS_6612_001
78M6612 Data Sheet
1.5.10 Hardware Watchdog Timer
V1
V3P3
V3P3 - 10mV
WDT disabled
V3P3 400mV
Normal
operation,
WDT
enabled
VBIAS
In addition to the basic watchdog timer included in the 80515 MPU, an
independent, robust, fixed-duration, watchdog timer (WDT) is included in
the device. It uses the crystal oscillator as its time base and must be
refreshed by the MPU firmware at least every 1.5 seconds. When not
refreshed on time the WDT overflows, and the part is reset as if the
RESET pin were pulled high, except that the I/O RAM bits will be
maintained. 4096 oscillator cycles (or 125 ms) after the WDT overflow,
the MPU will be launched from program address 0x0000. Asserting
ICR_E will deactivate the WDT.
The WDT can also be disabled by tying the V1 pin to V3P3. Of course,
this also deactivates V1 power fault detection. Since there is no method
in firmware to disable the crystal oscillator or the WDT, it is guaranteed
that whatever state the part might find itself in, upon WDT overflow, the
part will be reset to a known state.
Battery
modes
0V
Figure 4: Functions Defined by V1
1.5.11 Test Ports (TXUXOUT pin)
One out of 16 digital or 8 analog signals can be selected to be output on the TMUXOUT pin. The
function of the multiplexer is described in the applicable firmware documentation.
Rev 2
17
78M6612 Data Sheet
DS_6612_001
2 Functional Description
2.1
Theory of Operation
The energy delivered by a power source into a load can be expressed as:
t
E = ∫ V (t ) I (t )dt
0
The following formulas apply for wide band mode (true RMS):
•
P = ∑ (i(t) * v(t))
•
•
•
Q = √(S – P )
S=V*I
V = √∑v(t)2
•
I = √∑i(t)2
2
2
For actual measurement equations, refer to the applicable 78M6612 Firmware Description Document.
For some applications, not only voltage and current amplitudes, but also phase angles and harmonic
content may change constantly. Thus, simple RMS measurements are inherently inaccurate. A modern
solid-state electricity measurement IC such as the 78M6612 functions by emulating the integral operation
above, i.e. it processes current and voltage samples through an ADC at a constant frequency. As long
as the ADC resolution is high enough and the sample frequency is beyond the harmonic range of
interest, the current and voltage samples, multiplied with the time period of sampling will yield an accurate
quantity for the momentary energy. Summing up the momentary energy quantities over time will result in
accumulated energy.
500
400
300
200
100
0
0
5
10
15
20
-100
-200
-300
Current [A]
Voltage [V]
Energy per Interval [Ws]
-400
Accumulated Energy [Ws]
-500
Figure 5: Voltage, Current, Momentary and Accumulated Energy
Figure 5 shows the shapes of V(t), I(t), the momentary power and the accumulated power, resulting from
50 samples of the voltage and current signals over a period of 20 ms. The application of 240 VAC and
100 A results in an accumulation of 480 Ws (= 0.133 Wh) over the 20 ms period, as indicated by the
Accumulated Power curve. The described sampling method works reliably, even in the presence of
dynamic phase shift and harmonic distortion.
18
Rev 2
DS_6612_001
2.2
2.2.1
78M6612 Data Sheet
Fault and Reset Behavior
Reset Mode
When the RESET pin is pulled high, all digital activity stops. The oscillator and RTC module continue to
run. Additionally, all I/O RAM 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
real time clock after RESET goes low, at which time the MPU begins executing its preboot and boot
sequences from address 00.
2.2.2
Power Fault Circuit
The 78M6612 includes a comparator to monitor system power fault conditions. When the output of the
comparator falls (V1<VBIAS), the PLL status bits in the I/O RAM are zeroed and the IC power downs.
Once system power returns, the MPU remains in reset and does not start until 2048 to 4096 CK32 clock
cycles later. Program execution starts at address 0x00. MPU RAM will be re-initialized.
2.3
Data Flow
The data flow between the Compute Engine (CE) and the MPU is shown in Figure 6. In a typical
application, the 32-bit CE sequentially processes the samples from the current and voltage inputs on pins
2
IA, VA, IB, and VB, performing calculations to measure active power (Wh), reactive power (VARh), A h,
2
and V h for four-quadrant measurement. These measurements are then accessed by the MPU,
processed further and output using the peripheral devices available to the MPU.
Pulses
IRQ
Samples
CE
Pr Processo
e
r
Data
MP
UPos -
Processed
Metering
Data
Processo
t
r
I/O RAM (Configuration RAM)
Figure 6: MPU/CE Data Flow
Rev 2
19
78M6612 Data Sheet
2.4
DS_6612_001
CE/MPU Communication
Figure 7 shows the functional relationship between the CE and the MPU. The CE is controlled by the
MPU via shared registers in the I/O RAM and RAM. The CE outputs two interrupt signals to the MPU to
indicate the CE is actively processing data and the CE is updating data to the output region of the RAM.
PULSES
VAR (DIO7)
W
(DIO6)
VARSU
M
AD
C
Mux
Ctrl
SAMPLES
C
E
WSUM
DISPLAY (Memory
Mapped
LCD
Segments)
APULSEW
APULSE
R
EXT_PULS
E
SAG CONTROL
MP
U
DATA
CE_BUS
Y
XFER_BUSY
SERIAL
(UART0/1)
EEPROM
(I2C
)
DIO
INTERRUPTS
I/O RAM (CONFIGURATION RAM)
Figure 7: MPU/CE Communication
20
Rev 2
DS_6612_001
78M6612 Data Sheet
3 Application Information
3.1
Connection of Sensors (CT, Resistive Shunt)
Figure 8, Figure 9, and Figure 10 show how resistive voltage dividers, resistive current shunts, and
current transformers are connected to the voltage and current inputs of the 78M6612.
Figure 8: Resistive Voltage Divider
Figure 9: Resistive Current Shunt
Figure 10: Current Transformer
Rev 2
21
78M6612 Data Sheet
3.2
DS_6612_001
Connecting 5 V Devices
All digital input pins of the 78M6612 are compatible with external 5 V devices. I/O pins configured as
inputs do not require current-limiting resistors when they are connected to external 5 V devices.
3.3
Temperature Measurement
Measurement of absolute temperature uses the on-chip temperature sensor and applying the following
formula:
T=
( N (T ) − N n )
+ Tn
Sn
In the above formula, T is the temperature in °C, N(T) is the ADC count at temperature T, Nn is the ADC
count at 25°C, Sn is the sensitivity in LSB/°C and Tn is +25 °C.
3.4
Temperature Compensation
Temperature Coefficients: The internal voltage reference is calibrated during device manufacture.
The temperature coefficients TC1 and TC2 are given as constants that represent typical component
2
behavior (in µV/°C and µV/°C , respectively).
2
Since TC1 and TC2 are given in µV/°C and µV/°C , respectively, the value of the VREF voltage
2
(1.195V) has to be taken into account when transitioning to PPM/°C and PPM/°C . This means
that PPMC = 26.84*TC1/1.195, and PPMC2 = 1374*TC2/1.195).
Temperature Compensation: The CE provides the bandgap temperature to the MPU, which then may
digitally compensate the power outputs for the temperature dependence of VREF.
The MPU, not the CE, is entirely in charge of providing temperature compensation. The MPU applies the
following formula to determine GAIN_ADJ (address 0x12). In this formula TEMP_X is the deviation from
nominal or calibration temperature expressed in multiples of 0.1°C:
GAIN _ ADJ = 16385 +
TEMP _ X ⋅ PPMC TEMP _ X 2 ⋅ PPMC 2
+
214
2 23
In a power and energy measurement unit, the 78M6612 is not the only component contributing to
temperature dependency. A whole range of components (e.g. current transformers, resistor
dividers, power sources, filter capacitors) will contribute temperature effects. Since the output of
the on-chip temperature sensor is accessible to the MPU, temperature-compensation mechanisms
with great flexibility are possible (e.g. system-wide temperature correction over the entire unit rather than
local to the chip).
22
Rev 2
DS_6612_001
3.5
78M6612 Data Sheet
Connecting LCDs
The 78M6612 has an on-chip LCD controller capable of controlling static or multiplexed LCDs. Figure 11
shows the basic connection for an LCD.
78M6612
LCD
segments
commons
Figure 11: Connecting LCDs
The LCD segment pins can be organized in the following groups:
• Seventeen pins are dedicated LCD segment pins (SEG0 to SEG13, SEG16 to SEG18).
• Four pins are dual-function pins CKTEST/SEG19, E_RXTX/SEG38, E_TCLK/SEG33, and
E_RST/SEG32.
• Fourteen pins are available as combined DIO and segment pins SEG24/DIO4 to SEG31/DIO11,
SEG34/DIO14 to SEG37/DIO17, SEG39/DIO19, and SEG40/DIO20.
• The QFN-68 package adds an additional combination pin, SEG41/DIO21. Also adds two additional
LCD segment pins, SEG13 and SEG14.
3.6
Connecting I2C EEPROMs
I2C EEPROMs or other I2C compatible devices should be connected to the DIO pins DIO4 and DIO5, as
shown in Figure 12.
Pull-up resistors of roughly 10 kΩ to V3P3D should be used for both SCL and SDA signals. The
2
DIO_EEX register in I/O RAM must be set to 01 in order to convert the DIO pins DIO4 and DIO5 to I C
pins SCL and SDA.
V3P3D
10k Ω
78M6612
10k Ω
EEPROM
DIO4
SCL
DIO5
SDA
.
2
Figure 12: I C EEPROM Connection
Rev 2
23
78M6612 Data Sheet
3.7
DS_6612_001
Connecting Three-Wire EEPROMs
µWire EEPROMs and other compatible devices should be connected to the DIO pins DIO4 and DIO5, as
shown in Figure 13 and described below:
•
•
DIO5 connects to both the DI and DO pins of the three-wire device.
The CS pin must be connected to a vacant DIO pin of the 78M6618.
•
•
In order to prevent bus contention, a 10 kΩ to resistor is used to separate the DI and DO signals.
The CS and CLK pins should be pulled down with resistors to prevent operation of the three-wire
device on power-up, before the 78M6618 can establish a stable signal for CS and CLK.
The DIO_EEX register in I/O RAM must be set to 2 (b10) in order to convert the DIO pins DIO4 and
DIO5 to µWire pins.
•
The µ-Wire EEPROM interface is only functional when MPU_DIV[2:0] = 000.
78M6612
V3P3D
10k Ω
10k Ω
EEPROM
SCLK
DI
DO
CS
DIO4
DIO5
DIOn
Figure 13: Three-Wire EEPROM Connection
3.8
UART0 (TX0/RX0)
The UART0 RX0 pin should be pulled down by a 10 kΩ resistor and additionally protected by a 100 pF
ceramic capacitor, as shown in Figure 14.
78M6612
RX0
TX0
100pF
10kΩ
RX
RX0
TX
TX0
Figure 14: Connections for the RX0 Pin
24
Rev 2
DS_6612_001
3.9
78M6612 Data Sheet
UART1 (TX1/RX1)
The TX1 and RX1 pins can be used for a regular serial interface (by connecting a RS-232 transceiver for
example), or they can be used to directly operate optical components (for example, an infrared diode and
phototransistor implementing a FLAG interface).
3.10 Connecting V1 and Reset Pins
A voltage divider should be used to establish that V1 is in a safe range (see Figure 15). V1 must be
lower than 2.9 V in all cases in order to keep the hardware watchdog timer enabled. A series 5 kΩ
resistor (R3) and a capacitor to ground (C1) are added for enhanced EMC immunity. The parallel
impedance of R1 and R2 should be approximately 8 kΩ to 10 kΩ in order to provide hysteresis for the
power fault monitor.
V3P3
R3
R1
5kΩ
C1
100pF
R2
GND
V1
Figure 15: Voltage Divider for V1
Even though a functional power and measurement unit will not necessarily need a reset switch, it is useful to
have a reset pushbutton switch for prototyping, as shown in Figure 16, left side. The RESET signal may be
sourced from V3P3SYS, or VBAT (if a battery is present), or from a combination of these sources, depending
on the application.
For production, the RESET pin should be protected by the external components shown in Figure 16, right
side. R1 should be in the range of 100 Ω and mounted as closely as possible to the IC. The RESET pin
can also be directly connected to ground.
VBAT/
V3P3D
V3P3D
R2
78M6612
78M6612
1k Ω
Reset
Switc
h
1nF
10k Ω
R1
RESE
T
DGN
D
RESET
100 Ω
R1
DGND
Figure 16: External Components for RESET: Development Circuit (Left), Production Circuit (Right)
Rev 2
25
78M6612 Data Sheet
DS_6612_001
3.11 Connecting the Emulator Port Pins
Even when the emulator is not used, small shunt capacitors to ground (22 pF) should be used for
protection from EMI as illustrated in Figure 17. Production boards should have the ICE_E pin connected
to ground.
LCD
Segments
(optional
)
V3P3D
62Ω
78M661
2
ICE_E
E_RST
6 Ω
2
62 Ω
22p
F
22p
F
22p
F
E_RXT
E_RXTX
X
E_TCL
E_TCLK
K
Figure 17: External Components for the Emulator Interface
3.12 Flash Programming
Operational or test code can be programmed into the Flash memory using either an in-circuit emulator or
the Flash Programmer Module (TFP2) available from Maxim. The Flash programming procedure uses
the E_RST, E_RXTX, and E_TCLK pins.
3.13 MPU Firmware Library
Any applications-specific MPU functions mentioned above are available from Maxim as a standard ANSI
C library and as ANSI “C” source code. Sample application code using the measurement library is preprogrammed in Evaluation Kits for the 78M6618 IC and can be pre-programmed into engineering IC
samples for system evaluation. Application code allows for quick and efficient evaluation of the IC
without having to write firmware or having to purchase an in-circuit emulator (ICE). A Software Licensing
Agreement (SLA) can be signed to receive either the source Flash HEX file for use in a production
environment or source code and SDK documentation for modification.
3.14 Crystal Oscillator
The oscillator drives a standard 32.768 kHz watch crystal. The oscillator has been designed specifically
to handle these crystals and is compatible with their high impedance and limited power handling
capability. Good layouts will have XIN and XOUT shielded from each other.
Since the oscillator is self-biasing, an external resistor must not be connected across the crystal.
26
Rev 2
DS_6612_001
78M6612 Data Sheet
3.15 Measurement Calibration
Once the 78M6612 energy measurement device has been installed in a measurement system, it is
typically calibrated. A complete calibration includes the following:
•
Calibration of the metrology section, i.e. calibration for tolerances of the current sensors, voltage
dividers and signal conditioning components as well as of the internal reference voltage (VREF).
•
Establishment of the reference temperature (Section 3.3) for temperature measurement and
temperature compensation (Section 3.4).
The metrology section can be calibrated using the gain and phase adjustment factors accessible to the
CE. The gain adjustment is used to compensate for tolerances of components used for signal
conditioning, especially the resistive components. Phase adjustment is provided to compensate for
phase shifts introduced by certain types of current sensors or by the effects of reactive power supplies.
Due to the flexibility of the MPU firmware, any calibration method, such as calibration based on energy, or
current and voltage can be implemented. It is also possible to implement segment-wise calibration
(depending on current range).
Rev 2
27
78M6612 Data Sheet
DS_6612_001
4 Electrical Specifications
4.1
Absolute Maximum Ratings
Table 5 shows the absolute maximum ranges for the device. Stresses beyond Absolute Maximum
Ratings may cause permanent damage to the device. These are stress ratings only and functional
operation at these or any other conditions beyond those indicated under recommended operating
conditions (Section 4.3) is not implied. Exposure to absolute-maximum-rated conditions for extended
periods may affect device reliability. All voltages are with respect to GNDA.
Table 5: Absolute Maximum Ratings
Supplies and Ground Pins
V3P3SYS, V3P3A
-0.5 V to 4.6 V
VBAT
-0.5 V to 4.6 V
GNDD
-0.5 V to +0.5 V
Analog Output Pins
V3P3D
-10 mA to 10 mA,
-0.5 V to 4.6 V
VREF
-10 mA to +10 mA,
-0.5 V to V3P3A+0.5 V
V2P5
-10 mA to +10 mA,
-0.5 V to 3.0 V
Analog Input Pins
IA, VA, IB, VB, V1
-10 mA to +10 mA
-0.5 V to V3P3A+0.5 V
XIN, XOUT
-10 mA to +10 mA
-0.5 V to 3.0 V
All Other Pins
Configured as SEG or COM drivers
-1 mA to +1 mA,
-0.5 to V3P3D+0.5
Configured as Digital Inputs
-10 mA to +10 mA,
-0.5 to 6 V
Configured as Digital Outputs
-15 mA to +15 mA,
-0.5 V to V3P3D+0.5 V
All other pins
-0.5 V to V3P3D+0.5 V
Temperature and ESD Stress
Operating junction temperature (peak, 100 ms)
140 °C
Operating junction temperature (continuous)
125 °C
Storage temperature
-45 °C to +165 °C
Solder temperature – 10 second duration
250 °C
ESD stress on all pins
4 kV
Stresses beyond Absolute Maximum Ratings may cause permanent damage to the device. These are
stress ratings only and functional operation at these or any other conditions beyond those indicated under
“recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for
extended periods may affect device reliability. All voltages are with respect to GNDA.
28
Rev 2
DS_6612_001
4.2
78M6612 Data Sheet
Recommended External Components
Table 6: Recommended External Components
Name
From
To
C1
V3P3A
AGND
C2
V3P3D
CSYS
Value
Unit
Bypass capacitor for 3.3V supply.
≥0.1±20%
µF
DGND
Bypass capacitor for 3.3V output.
0.1±20%
µF
V3P3SYS
DGND
Bypass capacitor for V3P3SYS.
≥1.0±30%
µF
C2P5
V2P5
DGND
Bypass capacitor for V2P5.
0.1±20%
µF
XTAL
XIN
XOUT
32.768 kHz crystal – electrically similar to
ECS .327-12.5-17X or Vishay XT26T, load
capacitance 12.5 pF.
32.768
kHz
CXS †
XIN
AGND
27±10%
pF
XOUT
AGND
Load capacitor for crystal (exact value
depends on crystal specifications and
parasitic capacitance of board).
27±10%
pF
CXL
†
Function
†
Depending on trace capacitance, higher or lower values for CXS and CXL must be used. Capacitance
from XIN to GNDD and XOUT to GNDD (combining pin, trace and crystal capacitance) should be 35 pF
to 37 pF.
4.3
Recommended Operating Conditions
Table 7: Recommended Operation Conditions
Parameter
Condition
Min
Typ
Max
Unit
V3P3SYS, V3P3A: 3.3V Supply Voltage
V3P3A and V3P3SYS must be at the
same voltage
Normal Operation
3.0
3.3
3.6
V
3.6
V
VBAT
No Battery
Externally Connect to V3P3SYS
Battery Backup
BRN and LCD modes
SLEEP mode
3.0
2.0
3.8
3.8
V
V
-40
+85
ºC
Operating Temperature
Rev 2
Battery Backup
0
29
78M6612 Data Sheet
4.4
4.4.1
DS_6612_001
Performance Specifications
Input Logic Levels
Table 8: Input Logic Levels
Parameter
Condition
Min
†
Digital high-level input voltage , VIH
Typ
Max
2
V
†
Digital low-level input voltage , VIL
Input pull-up current, IIL
E_RXTX,
E_RST, CKTEST
Other digital inputs
VIN=0V, ICE_E=1
Input pull down current, IIH
ICE_E
Other digital inputs
VIN=V3P3D
Unit
0.8
V
µA
µA
µA
µA
µA
10
10
-1
0
100
100
1
10
-1
0
100
1
†
In battery powered modes, digital inputs should be below 0.3 V or above 2.5 V to minimize battery
current.
4.4.2
Output Logic Levels
Table 9: Output Logic Levels
Parameter
Condition
Digital high-level output voltage VOH
Min
Typ
Max
Unit
ILOAD = 1 mA
V3P3D-0.4
V
ILOAD = 15 mA
V3P3D-0.6
V
ILOAD = 1 mA
0
0.4
V
ILOAD = 15 mA
0.8
V
TX1 VOH (V3P3D-TX1)
ISOURCE=1 mA
0.4
V
TX1 VOL
ISINK=20 mA
0.7
V
Max
Unit
-20
+15
mV
0.8
1.2
µA
10
µs
-10
mV
Digital low-level output voltage VOL
4.4.3
Power-Fault Comparator
Table 10: Power-Fault Comparator Performance Specifications
Parameter
Condition
Offset Voltage: V1-VBIAS
Hysteresis Current: V1
Vin = VBIAS – 100 mV
Response Time: V1
+100 mV overdrive
WDT Disable Threshold (V1-V3P3A)
30
Min
2
-400
Typ
5
Rev 2
DS_6612_001
4.4.4
78M6612 Data Sheet
Battery Monitor
Table 11: Power-Fault Comparator Performance Specifications (BME=1)
Parameter
Condition
Load Resistor
LSB Value - does not include the 9-bit
left shift at CE input.
FIR_LEN=0
FIR_LEN=1
Offset Error
4.4.5
Min
Typ
Max
Unit
27
45
63
kΩ
-6.0
-2.6
-5.4
-2.3
-72
-4.9
-2.0
µV
µV
+100
mV
Typ
Max
Unit
6.1
7.7
mA
+300
nA
-200
Supply Current
Table 12: Supply Current Performance Specifications
Parameter
Condition
V3P3A + V3P3SYS current
VBAT current
Normal Operation,
V3P3A=V3P3SYS=3.3V
MPU_DIV[1:0]=3 (614 kHz)
CKOUT_E[1:0]=00, CE_EN=1,
RTM_E=0, ECK_DIS=1,
ADC_E=1, ICE_E=0
Min
-300
V3P3A + V3P3SYS current
vs. MPU clock frequency
Same conditions as above
0.5
V3P3A + V3P3SYS current,
Write Flash
Normal Operation as above,
except write Flash at maximum
rate, CE_E=0, ADC_E=0
9.1
10
mA
48
65
120
150
µA
µA
5.7
8.5
15
5.0
10
µA
µA
µA
µA
VBAT=3.6V
BROWNOUT mode, <25°C
BROWNOUT mode, <>5°C
VBAT current †
LCD Mode, 25 °C
LCD mode, over temperature
SLEEP Mode, 25 °C
Sleep mode, over temperature
2.9
mA/
MHz
†
Current into V3P3A and V3P3SYS pins is not zero if voltage is applied at these pins in brownout, LCD or
sleep modes.
4.4.6
V3P3D Switch
Table 13: V3P3D Switch Performance Specifications
Parameter
Condition
Min
Typ
Max
Unit
On resistance – V3P3SYS to V3P3D
| IV3P3D | ≤ 1 mA
10
Ω
On resistance – VBAT to V3P3D
| IV3P3D | ≤ 1 mA
40
Ω
Rev 2
31
78M6612 Data Sheet
4.4.7
DS_6612_001
2.5V Voltage Regulator
Unless otherwise specified, load = 5 mA.
Table 14: 2.5 V Voltage Regulator Performance Specifications
Parameter
Condition
Voltage overhead V3P3-V2P5
Reduce V3P3 until
V2P5 drops 200 mV
PSSR ∆V2P5/∆V3P3
RESET=0, iload=0
4.4.8
Min
Typ
Max
Unit
440
mV
+3
mV/V
-3
Low Power Voltage Regulator
Unless otherwise specified, V3P3SYS=V3P3A=0.
Table 15: Low-Power Voltage Regulator Performance Specifications
Parameter
Condition
Min
Typ
Max
Unit
2.0
2.5
2.7
V
V2P5
ILOAD=0
V2P5 load regulation
ILOAD=0 mA to 1 mA
30
mV
VBAT voltage requirement
ILOAD=1 mA,
Reduce VBAT until
REG_LP_OK=0
3.0
V
PSRR ΔV2P5/ΔVBAT
ILOAD=0
50
mV/V
Max
Unit
1
µW
XIN to XOUT Capacitance
3
pF
Capacitance to DGND
XIN
XOUT
5
5
pF
pF
4.4.9
-50
Crystal Oscillator
Table 16: Crystal Oscillator Performance Specifications
Parameter
Maximum Output Power to Crystal
32
Condition
Crystal connected
Min
Typ
Rev 2
DS_6612_001
78M6612 Data Sheet
4.4.10 VREF, VBIAS
Unless otherwise specified, VREF_DIS=0.
Table 17: VREF, VBIAS Performance Specifications
Parameter
Condition
VREF output voltage, VNOM(25)
Ta = 22ºC
Min
Typ
Max
Unit
1.193
1.195
1.197
V
50
mV
2.5
kΩ
VREF chop step
VREF output impedance
VREF_CAL =1,
ILOAD = 10 µA, -10 µA
VNOM definition1
VNOM (T ) = VREF (22) + (T − 22)TC1 + (T − 22) 2 TC 2
VREF temperature coefficients
TC1
TC2
VREF aging
1
VREF(T) deviation from VNOM(T)
VREF (T ) − VNOM (T ) 10 6
62
VNOM
Ta = -40ºC to +85ºC
-40
VBIAS voltage
Ta = 25 ºC
Ta = -40 ºC to 85 ºC
(-1%)
(-4%)
V
+7.0
-0.341
µV/ºC
µV/°C2
±25
ppm/
year
+40
ppm/º
C
(+1%)
(+4%)
V
V
Max
Unit
-0.1
0+.1
V
1.6
1.6
This relationship describes the nominal behavior of VREF at different temperatures.
4.4.11 LCD Drivers
The information in Table 18 applies to all COM and SEG pins.
Table 18: LCD Drivers Performance Specifications
Parameter
Condition
Min
Typ
VLC2 Max Voltage
With respect to VLCD
VLC1 Voltage,
⅓ bias
½ bias
With respect to 2*VLC2/3
With respect to VLC2/2
-4
-3
0
+2
%
%
VLC0 Voltage,
⅓ bias
½ bias
With respect to VLC2/3
With respect to VLC2/2
-3
-3
+2
+2
%
%
VLCD is V3P3SYS in MISSION mode and VBAT in BROWNOUT and LCD modes.
Rev 2
33
78M6612 Data Sheet
DS_6612_001
4.4.12 ADC Converter, V3P3A Referenced
FIR_LEN=0, VREF_DIS=0, LSB values do not include the 9-bit left shift at CE input.
Table 19: ADC Converter Performance Specifications
Parameter
Condition
Recommended Input Range
(Vin-V3P3A)
Voltage to Current Crosstalk:
10 6 *Vcrosstalk
cos(∠Vin − ∠Vcrosstalk )
Vin
Vin = 200 mV peak,
65 Hz, on VA
Vcrosstalk = largest
measurement on IA or IB
Min
Typ
Max
Unit
-250
250
mV
peak
-10
10
μV/V
-75
-90
dB
dB
90
kΩ
THD (First 10 harmonics)
250 mV-pk
20 mV-pk
Vin=65 Hz,
64 kpts FFT, BlackmanHarris window
Input Impedance
Vin=65 Hz
Temperature coefficient of Input
Impedance
Vin=65 Hz
1.7
Ω/°C
LSB size
FIR_LEN=0
FIR_LEN=1
357
151
nV/LSB
Digital Full Scale
FIR_LEN=0
FIR_LEN=1
+884736
±2097152
LSB
ADC Gain Error vs
%Power Supply Variation
10 6 ∆Nout PK 357nV / VIN
100 ∆V 3P3 A / 3.3
Vin=200 mV pk, 65 Hz
V3P3A=3.0V, 3.6V
Input Offset (Vin-V3P3A)
40
-10
50
ppm/%
10
mV
Max
0.4
0.7
Unit
V
V
Max
Unit
4.4.13 UART1 Interface
Table 20: UART1 Interface Performance Specifications
Parameter
TX1 VOH (V3P3D-TX1)
TX1 VOL
Condition
ISOURCE=1 mA
ISINK=20 mA
Min
Typ
4.4.14 Temperature Sensor
Table 21: Temperature Sensor Performance Specifications
Parameter
Nominal Sensitivity (Sn)
†
Nominal (Nn) † †
Temperature Error†
 ( N (T ) − N n )

ERR = T − 
+ Tn 
Sn


†
Condition
TA=25ºC, TA=75ºC,
FIR_LEN = 1
Nominal relationship:
N(T)= Sn*(T-Tn)+Nn
TA = -40ºC to +85ºC
Tn = 25°C
Min
-10
Typ
-2180
LSB/ºC
1.0
10
LSB
6
+10
ºC
LSB values do not include the 9-bit left shift at CE input.
Nn is measured at Tn during calibration and is stored in MPU or CE for use in temperature calculations.
††
34
Rev 2
DS_6612_001
4.5
4.5.1
78M6612 Data Sheet
Timing Specifications
RAM and Flash Memory
Table 22: RAM and Flash Memory Specifications
Parameter
CE DRAM wait states
Flash Read Pulse Width
Flash write cycles
Flash data retention
Flash data retention
Flash byte writes between page or
mass erase operations
Condition
Min
CKMPU = 4.9152 MHz
CKMPU = 1.25 MHz
CKMPU = 614 kHz
V3P3A=V3P3SYS=0
BROWNOUT MODE
-40 °C to +85 °C
25 °C
85 °C
5
2
1
Typ
Max
Unit
Cycles
Cycles
Cycles
30
100
20,000
100
10
ns
Cycles
Years
Years
2
Cycles
Max
Unit
Write Time per Byte
42
µs
Page Erase (512 bytes)
20
ms
Mass Erase
200
ms
Max
Unit
4.5.2
Flash Memory Timing
Table 23: Flash Memory Timing Specifications
Parameter
4.5.3
Condition
Min
Typ
EEPROM Interface
Table 24: EEPROM Interface Timing
Parameter
Condition
2
Write Clock frequency (I C)
Write Clock frequency (3-wire)
4.5.4
Min
Typ
CKMPU=4.9152 MHz,
Using interrupts
78
kHz
CKMPU=4.9152 MHz,
“bit-banging” DIO4/5
150
kHz
CKMPU=4.9152 MHz
500
kHz
RESET and V1
Table 25: RESET and V1 Timing
Parameter
Condition
Min
Typ
Reset pulse fall time
Reset pulse width
V1 Response Time
4.5.5
Max
Unit
1
µs
5
+100 mv overdrive
µs
10
37
100
µs
Min
Typ
Max
Unit
2255
year
RTC
Table 26: RTC Range
Parameter
Range for date
Rev 2
Condition
2000
35
78M6612 Data Sheet
DS_6612_001
5 Packaging
5.1
Pinout
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
E_TCLK/SEG33
E_RST/SEG32
GNDD
XOUT
TEST
XIN
GNDD
RX1/DIO1
V1
VREF
IA
IB
VB
VA
V3P3A
GNDA
5.1.1
64-Pin LQFP Package
TERIDIAN
78M6612-IGT
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
RESET
V2P5
VBAT
RX0
SEG40/DIO20
SEG31/DIO11
SEG30/DIO10
SEG29/DIO9
SEG28/DIO8
SEG27/DIO7
SEG26/DIO6
SEG25/DIO5
SEG24/DIO4
ICE_E
SEG18
SEG17
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
SEG0
SEG1
SEG2
SEG34/DIO14
SEG35/DIO15
SEG36/DIO16
SEG39/DIO19
SEG6
SEG7
SEG8
SEG9
SEG10
SEG11
SEG12
SEG13
SEG16
GNDD
E_RXTX/SEG38
TX1/DIO2
TMUXOUT
TX0
SEG3
V3P3D
SEG19/CKTEST
V3P3SYS
SEG4
SEG5
SEG37/DIO17
COM0
COM1
COM2
COM3
Figure 18: 64-Pin LQFP Pinout
36
Rev 2
DS_6612_001
5.1.2
78M6612 Data Sheet
Package Outline (LQFP 64)
11.7
12.3
11.7
+
12.3
PIN No. 1 Indicator
9.8
10.2
0.60 Typ.
0.50 Typ.
0.00
0.20
0.14
0.28
1.40
1.60
NOTE: Controlling dimensions are in mm.
Rev 2
37
78M6612 Data Sheet
5.1.3
DS_6612_001
Recommended PCB Land Pattern for the LQFP-64 Package
x
y
e
A
G
x
y
e
A
G
Recommended PCB Land Pattern Dimensions
Symbol
Description
Typical
Dimension
e
Lead pitch
0.5 mm
x
Pad width
0.25 mm
y
Pad length. See Note.
2.0 mm
A
7.75 mm
G
9.0 mm
Note: The y dimension has been elongated to allow for hand soldering and reworking. Production
assembly may allow this dimension to be reduced as long as the G dimension is maintained.
38
Rev 2
DS_6612_001
GNDA
V3P3A
VA
IB
VB
IA
VREF
V1
RX1/DIO1
XIN
GNDD
XOUT
TEST
GNDD
E_RST/SEG32
E_TCLK/SEG33
Pinout
SEG41/DIO21
GNDD
68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52
51
1
E_RXTX/SEG38
2
50
V2P5
RESET
TX1/DIO2
3
49
VBAT
TMUXOUT
4
48
RX0
DIO3
5
47
SEG40/DIO20
TX0
6
46
SEG31/DIO11
45
SEG30/DIO10
44
SEG29/DIO9
43
SEG28/DIO8
42
SEG27/DIO7
SEG3
7
V3P3D
8
CKTEST/SEG19
9
V3P3SYS
10
TERIDIAN
78M6612-IM
COM3
35
17
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
SEG16
SEG15
SEG17
SEG14
SEG18
36
SEG13
37
16
SEG12
15
COM2
SEG11
COM1
SEG9
ICE_E
SEG10
SEG24/DIO4
38
SEG8
39
14
SEG7
13
COM0
SEG6
SEG37/DIO17
SEG39/DIO19
SEG25/DIO5
SEG36/DIO16
SEG26/DIO6
40
SEG35/DIO15
41
12
SEG34/DIO14
11
SEG0
SEG4
SEG5
SEG2
5.2.1
68-Pin QFN Package
SEG1
5.2
78M6612 Data Sheet
Figure 19: 68-Pin QFN Pinout
Rev 2
39
78M6612 Data Sheet
5.2.2
DS_6612_001
Package Outline
0.850
Dimensions (in mm):
*) Pin length is nominally 0.4 mm (min. 0.3 mm, max 0.4 mm).
**) Exposed pad is internally connected to GNDD.
40
Rev 2
DS_6612_001
5.2.3
78M6612 Data Sheet
Recommended PCB Land Pattern for the QFN-68 Package
Recommended PCB Land Pattern Dimensions
Symbol
Description
Typical
Dimension
e
Lead pitch
0.4 mm
x
Pad width
0.23 mm
y
Pad length. See Note 3.
0.8 mm
d
See Note 1.
6.3 mm
A
6.63 mm
G
7.2 mm
Note 1: Do not place unmasked vias in region denoted by dimension d.
Note 2: Soldering of bottom internal pad is not required for proper operation.
Note 3: The y dimension has been elongated to allow for hand soldering and reworking. Production
assembly may allow this dimension to be reduced as long as the G dimension is maintained.
Rev 2
41
78M6612 Data Sheet
DS_6612_001
6 Pin Descriptions
6.1
Power/Ground Pins
Table 27: Power/Ground Pins
Name
Type
Circuit
GNDA
P
–
Analog ground: This pin should be connected directly to the ground
plane.
GNDD
P
–
Digital ground: This pin should be connected directly to the ground
plane.
V3P3A
P
–
Analog power supply: A 3.3V power supply should be connected to
this pin, must be the same voltage as V3P3SYS.
V3P3SYS
P
–
System 3.3 V supply. This pin should be connected to a 3.3 V power
supply.
V3P3D
O
13
Auxiliary voltage output of the chip, controlled by the internal 3.3 V
selection switch. In mission mode, this pin is internally connected to
V3P3SYS. In BROWNOUT mode, it is internally connected to VBAT.
This pin is floating in LCD and sleep mode.
VBAT
P
12
Battery backup power supply. A battery or super-capacitor is to be
connected between VBAT and GNDD. If no battery is used, connect
VBAT to V3P3SYS.
V2P5
O
10
Output of the internal 2.5 V regulator. A 0.1 µF capacitor to GNDA
should be connected to this pin.
6.2
Description
Analog Pins
Table 28: Analog Pins
Name
Type
Circuit
Description
IA, IB
I
6
Line Current Sense Inputs: These pins are voltage inputs to the
internal A/D converter. Typically, they are connected to the outputs of
current sensors. Unused pins must be connected to V3P3A.
VA, VB
I
6
Line Voltage Sense Inputs: These pins are voltage inputs to the
internal A/D converter. Typically, they are connected to the outputs
of resistor dividers. Unused pins must be connected to V3P3A or
tied to the voltage sense input that is in use.
V1
I
7
Comparator Input: This pin is a voltage input to the internal power-fail
comparator. The input voltage is compared to the internal BIAS
voltage (1.6 V). If the input voltage is above VBIAS, the comparator
output will be high (1). If the comparator output is lower, a voltage
fault will occur and the chip will be forced to battery mode.
VREF
O
9
Voltage Reference for the ADC. This pin is normally disabled by
setting the VREF_CAL bit in the I/O RAM and can then be left
unconnected. If enabled, a 0.1 µF capacitor to GNDA should be
connected.
XIN
XOUT
I
8
Crystal Inputs: A 32 kHz crystal should be connected across these
pins. Typically, a 27 pF capacitor is also connected from each pin to
GNDA. It is important to minimize the capacitance between these
pins. See the crystal manufacturer datasheet for details.
Pin types: P = Power, O = Output, I = Input, I/O = Input/Output
The circuit number denotes the equivalent circuit, as specified in Section 7 I/O Equivalent Circuits.
42
Rev 2
DS_6612_001
6.3
78M6612 Data Sheet
Digital Pins
Name
COM3,
COM2,
COM1,
COM0
SEG0…SEG18
Type
O
Circuit
5
O
5
SEG24/DIO4…
SEG31/DIO11
I/O
3, 4, 5
SEG34/DIO14
…
SEG37/DIO17,
SEG39/DIO19,
SEG40/DIO20
SEG41/DIO21
I/O
3, 4, 5
I/O
3, 4, 5
E_RXTX/SEG38
E_RST/SEG32
E_TCLK/SEG33
ICE_E
I/O
1, 4, 5
O
I
4, 5
2
CKTEST/SEG19
O
4, 5
TMUXOUT
RX1/DIO1
O
I/O
4
3, 4, 7
TX1/DIO2
I/O
3, 4
DIO3
RESET
I/O
I
3, 4
3
RX0
TX0
TEST
I
O
I
3
4
7
Description
LCD common outputs: These four pins provide the select signals for the
LCD display.
Dedicated LCD segment output pins. SEG 14 and SEG15 are only
available on the 68-pin package.
Multi-use pins, configurable as either LCD SEG driver or DIO. (DIO4 =
SCK, DIO5 = SDA when configured as EEPROM interface, WPULSE =
DIO6, VARPULSE = DIO7 when configured as pulse outputs). If unused,
these pins must be configured as DIOs and set to outputs by the
firmware.
Multi-use pins, configurable as either LCD SEG driver or DIO. If unused,
these pins must be configured as DIOs and set to outputs by the
firmware.
Multi-use pins, configurable as LCD driver or DIO (QFN 68 package only).
If unused, this pin must be configured as a DIO and set to an output
by the firmware.
Multi-use pins, configurable as either emulator port pins (when ICE_E
pulled high) or LCD SEG drivers (when ICE_E tied to GND).
ICE enable. When zero, E_RST, E_TCLK, and E_RXTX become SEG32,
SEG33, and SEG38 respectively. For production units, this pin should be
pulled to GND to disable the emulator port. This pin should be brought out
to the programming interface in order to create a way for reprogramming
parts that have the SECURE bit set.
Multi-use pin, configurable as either Clock PLL output or LCD segment
driver. Can be enabled and disabled by CKOUT_E[1:0].
Digital output test multiplexer. Controlled by TMUX[4:0].
Multi-use pin, configurable as UART1 Input or general DIO. When configured as RX1, this pin can optionally receive a signal from an external
photo-detector used in an IR serial interface. If unused, this pin must be
terminated to V3P3D or GNDD, or configured as a DIO and set to an
output by the firmware.
Multi-use pin, configurable as a transmit output from UART1 (or optionally
an Optical LED Transmit Output), WPULSE, RPULSE, or general DIO.
When configured as TX1, this pin is capable of directly driving an LED for
transmitting data in an IR serial interface. If unused, this pin must be left
open, or configured as a DIO and set to an output by the firmware.
DIO pin (QFN 68 package only)
This input pin resets the chip into a known state. For normal operation,
this pin is connected to GNDD. To reset the chip, this pin should be pulled
high. No external reset circuitry is necessary. Direct connect to ground in
normal operation.
UART input. If unused, this pin must be terminated to V3P3D or GNDD.
UART output.
Enables Production Test. Must be grounded in normal operation.
Pin types: P = Power, O = Output, I = Input, I/O = Input/Output
The circuit number denotes the equivalent circuit, as specified on the following page.
Rev 2
43
78M6612 Data Sheet
DS_6612_001
7 I/O Equivalent Circuits
V3P3D
V3P3D
V3P3A
110K
Digital
Input
Pin
CMOS
Input
LCD SEG
Output
Pin
LCD
Driver
GNDD
from
internal
reference
VREF
Pin
GNDA
GNDD
Digital Input Equivalent Circuit
Type 1:
Standard Digital Input or
pin configured as DIO Input
with Internal Pull-Up
V3P3D
VREF Equivalent Circuit
Type 9:
VREF
LCD Output Equivalent Circuit
Type 5:
LCD SEG or
pin configured as LCD SEG
V3P3A
V3P3D
Digital
Input
Pin
CMOS
Input
110K
GNDD
GNDD
Analog
Input
Pin
from
internal
reference
To
MUX
V2P5
Pin
GNDA
GNDD
Analog Input Equivalent Circuit
Type 6:
ADC Input
Digital Input
Type 2:
Pin configured as DIO Input
with Internal Pull-Down
V2P5 Equivalent Circuit
Type 10:
V2P5
V3P3D
V3P3A
Digital
Input
Pin
CMOS
Input
GNDD
Comparator
Input
Pin
To
Comparator
Power
Down
Circuits
VBAT
Pin
GNDA
Digital Input Type 3:
Standard Digital Input or
pin configured as DIO Input
GNDD
Comparator Input Equivalent
Circuit Type 7:
Comparator Input
VBAT Equivalent Circuit
Type 12:
VBAT Power
V3P3D
V3P3D
Digital
Output
Pin
CMOS
Output
GNDD
GNDD
Digital Output Equivalent Circuit
Type 4:
Standard Digital Output or
pin configured as DIO Output
44
from
V3P3SYS
Oscillator
Pin
V3P3D
Pin
To
Oscillator
GNDD
Oscillator Equivalent Circuit
Type 8:
Oscillator I/O
10
from
VBAT
40
V3P3D Equivalent Circuit
Type 13:
V3P3D
Rev 2
DS_6612_001
78M6612 Data Sheet
8 Ordering Information
Part Description
(Package,
accuracy)
Flash
Memory
Size
Packaging
Ordering Number
Package
Marking
78M6612
64-pin LQFP, 0.5%
(Lead(Pb)-free)
32KB
Bulk
78M6612-IGT/F
78M6612-IGT
78M6612
64-pin LQFP, 0.5%
(Lead(Pb)-free)
32KB
Tape & Reel
78M6612-IGTR/F
78M6612-IGT
78M6612
64-pin LQFP, 0.5%
(Lead(Pb)-free)
32KB
*Programmed,
Bulk
78M6612-IGT/F/P
78M6612-IGT
78M6612
64-pin LQFP, 0.5%
(Lead(Pb)-free)
32KB
*Programmed,
Tape & Reel
78M6612-IGTR/F/P
78M6612-IGT
78M6612
68-pin QFN, 0.5%
(Lead(Pb)-free)
32KB
Bulk
78M6612-IM/F
78M6612-IM
78M6612
68-pin QFN, 0.5%
(Lead(Pb)-free)
32KB
Tape & Reel
78M6612-IMR/F
78M6612-IM
78M6612
68-pin QFN, 0.5%
(Lead(Pb)-free)
32KB
*Programmed,
Bulk
78M6612-IM/F/P
78M6612-IM
78M6612
68-pin QFN, 0.5%
(Lead(Pb)-free)
32KB
*Programmed,
Tape & Reel
78M6612-IMR/F/P
78M6612-IM
Part
*Contact the factory for more information on programmed part options.
9
Contact Information
For more information about Maxim products or to check the availability of the 78M6613, contact technical
support at www.maxim-ic.com/support.
Rev 2
45
78M6612 Data Sheet
DS_6612_001
Revision History
REVISION
DATE
DESCRIPTION
1.0
4/1/2009
First publication.
1.3
5/7/2010
Moved firmware specific information to respective developers manuals.
Added Caution to Section 1.4.6: “Caution. If UART1 is being used for full
duplex operation, TX interrupts may be inadvertently cleared and thus a
TX safety timer is recommended.”
Added Caution to Section 1.4.6 about UART0 interrupts.
In Section 3.10, changed “I/O RAM register TX1DIS” to “I/O RAM register
TX1E”.
In Figure 18, corrected the name of pin 45 from “RX” to “RX0”.
2
1/12
Added Maxim logo.
46
Rev 2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit
patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
M a x i m I n t e g r a t e d P r o d u c t s , 1 2 0 S a n G a b r i e l D r iv e , S u n n y v a le , C A 9 4 0 8 6 4 0 8- 7 3 7 - 7 6 0 0
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