Datasheet

71M6511/71M6511H

Single-Phase Energy Meter IC

DATA SHEET

NOVEMBER 2010

A Maxim Integrated Products Brand

Real-Time Monitor

The CE contains a Real Time Monitor (RTM), which can be programmed to monitor four selectable CE RAM locations at full

sample rate. The four monitored locations are serially output to the TMUXOUT pin via the digital output multiplexer at the

beginning of each CE code pass (see the Test Ports Section for details)

CE Functional Overview

The ADC processes one sample per channel per multiplexer cycle. Figure 4 shows the timing of the samples taken during one

multiplexer cycle.

The number of samples processed during one accumulation cycle is controlled by the I/O RAM registers PRE_SAMPS

(0x2001[7:6]) and SUM_CYCLES (0x2001[5:0]). The integration time for each energy output is

PRE_SAMPS * SUM_CYCLES / 2520.6, where 2520.6 is the sample rate [Hz] (for MUX_DIV = 1)

For example, PRE_SAMPS = 42 and SUM_CYCLES = 50 will establish 2100 samples per accumulation cycle. PRE_SAMPS = 100

and SUM_CYCLES = 21 will result in the exact same accumulation cycle of 2100 samples or 833ms. After an accumulation

cycle is completed, the XFER_BUSY interrupt signals to the MPU that accumulated data are available.

1/32768Hz =

30.518µs

13/32768Hz = 397µs

per mux cycle

1/32768Hz =

30.518µs

13/32768Hz = 397µs

per mux cycle

Figure 4: Samples in Multiplexer Cycle

The end of each multiplexer cycle is signaled to the MPU by the CE_BUSY interrupt. At the end of each multiplexer cycle,

status information, such as sag data and the digitized input signal, is available to the MPU.

XFER_BUSY

Interrupt to MPU

20ms

833ms

XFER_BUSY

Interrupt to MPU

20ms

833ms

Figure 5: Accumulation Interval

Figure 5 shows the accumulation interval resulting from MUX_DIV = 1, PRE_SAMPS = 42 and SUM_CYCLES = 50, consisting of

2100 samples of 397µs each, followed by the XFER_BUSY interrupt. The sampling in this example is applied to a 50Hz signal.