Datasheet

71M6511/71M6511H

Single-Phase Energy Meter IC

DATA SHEET

NOVEMBER 2010

A Maxim Integrated Products Brand

GAIN_ADJ is a scaling factor for power measurements based on temperature (when in internal temperature compensation

mode). In general, for higher temperatures it is lower than 16384 and higher than 16384 for lower temperatures. GAIN_ADJ is

mainly dependent on the PPMC, PPMC2 and TEMP_X register values. This parameter is automatically computed by the CE

and is used by the CE for temperature compensation.

Address

Name Description

0x40 TEMP_X Deviation from Calibration temperature. LSB = 0.1

0x54 TEMP_RAW_X

Filtered, unscaled reading from temperature sensor. This

value should be written to TEMP_NOM during meter

calibration.

0x2E GAIN_ADJ

Scales all voltage and current inputs. 16384 provides

unity gain. Default is 16384. If EXT_TMP = 0, GAIN_ADJ

is updated by the CE.

Pulse Generation

Input variables: The combination of the PULSE_SLOW and PULSE_FAST parameters control the speed of the pulse rate. The

default values of 1 and 1 will maintain the original pulse rate given by the Kh equation.

WRATE controls the number of pulses that are generated per measured Wh and VARh quantities. The lower WRATE it is the

slower is the pulse rate for measured power quantity. The metering constant Kh is derived from WRATE as the amount of

energy measured for each pulse. That is, if Kh = 1Wh/pulse, a power applied to the meter of 120V and 30A results in one

pulse per second. If the load is 240V at 150A, ten pulses per second will be generated.

Control is transferred to the MPU for pulse generation if EXT_PULSE > 0. In this case, the pulse rate is determined by

APULSEW and APULSER. The MPU has to load the source for pulse generation in APULSEW and APULSER to generate pulses.

Irrespective of the EXT_PULSE, status the output pulse rate controlled by APULSEW and APULSER is implemented by the CE

only. By setting EXT_PULSE > 0, the MPU is providing the source for pulse generation. If EXT_PULSE is negative, W0SUM_X

and VAR0SUM_X are the default pulse generation sources. In this case, creep cannot be controlled since it is an MPU function.

The maximum pulse rate is F

/2= 1260.3Hz (MUX_DIV = 1).

PULSE_WIDTH allows adjustment of the pulse width for compatibility with calibration and other external equipment. When

MUX_DIV = 1, the minimum pulse width possible is 397µs.

The maximum time jitter is 397µs (for MUX_DIV = 1) and is independent of the number of pulses measured. Thus, if the pulse

generator is monitored for 1 second, the peak jitter is 397PPM. After 10 seconds, the peak jitter is 39.7PPM. The average jitter

is always zero. If it is attempted to drive either pulse generator faster than its maximum rate, it will simply output at its

maximum rate without exhibiting any roll-over characteristics. The actual pulse rate, using WSUM as an example, is:

FWSUMWRATEX

RATE

⋅⋅⋅

Where F

= 2520.6Hz (sampling frequency for MUX_DIV = 1) or 3276.8Hz (sampling frequency for MUX_DIV = 2) and X is the

pulse gain factor derived from CE variables PULSE_SLOW and PULSE_FAST (see table below).