ADE75 datasheet(66/148 Pages) AD

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ADE75xx/ADE71xx

Preliminary Technical Data

Rev. PrE | Page 66 of 148

the pulsed outputs. When WDIV =0 or 1, the DFC generates a

pulse each time 1 LSB in the energy register is accumulated. An

output pulse is generated when CFxDEN/CFxNUM number of

pulses are generated at the DFC output. Under steady load

conditions, the output frequency is proportional to the active,

reactive, Apparent power or Irms depending on the CFxSEL bit

in the MODE2 register (0x0C).

Both pulse outputs can be enabled or disabled by clearing or

setting respectively bits DISCF1 and DISCF2 in the MODE1

Both pulse outputs set a separate flag in the Interrupt Status

CF2 enable bits in the Interrupt Enable Register 2 SFR

(MIRQENM, 0xDA) are set, the 8052 core has a pending ADE

interrupt. The ADE interrupt stays active until the CF1 or CF2

status bits are cleared—see Energy measurement interrupts

section.

Pulse output configuration

The two pulse outputs circuitry have separate configuration bits

in the MODE2 register (0x0C). Setting CFxSEL bits to 0b00,

0b01 or 0b1x configure the DFC to create a pulse output

proportional to Active power, reactive power, or Apparent/Irms

respectively.

The selection between Irms and Apparent power is done by the

VARMSCFCON bit in the MODE2 register (0x0C). With this

selection, CF2 cannot be proportional to apparent power if CF1

is proportional to Irms and vice-versa.

Pulse output characteristic

The pulse output for both DFC stays low for 90ms if the pulse

period is larger than 180ms (5.56Hz). If the pulse period is

smaller than 180ms, the duty cycle of the pulse output is 50%.

The pulse output is active low and should be preferably

connected to an LED as shown on Figure 53.

VDD

Figure 53. CF Pulse output

The maximum output frequency, with ac input signals at full

scale and CFxNUM = 0x00 and CFxDEN = 0x00, is

approximately 21.1 kHz.

The ADE75XX/ADE71XX incorporates two registers,

CFxNUM[15:0] and CFxDEN[15:0] per DFC, to set the CFx

frequency. These are unsigned 16-bit registers, which can be

used to adjust the CFx frequency to a wide range of values.

These frequency-scaling registers are 16-bit registers, which can

scale the output frequency by 1/216 to 1 with a step of 1/216.

If the value 0 is written to any of these registers, the value 1

would be applied to the register. The ratio CFxNUM / CFxDEN

should be smaller than 1 to ensure proper operation. If the ratio

of the registers CFxNUM / CFxDEN is greater than 1, the register

values would be adjusted to a ratio of 1. For example, if the

output frequency is 1.562 kHz while the contents of CFxDEN

are 0 (0x000), then the output frequency can be set to 6.1 Hz by

writing 0xFF to the CFxDEN register.

ENERGY REGISTER SCALING

The ADE75XX/ADE71XX provides measurements of active,

reactive, and apparent energies that use separate paths and

filtering for calculation. The difference in data paths can result

in small differences in LSB weight between active, reactive and

apparent energy registers. These measurements are internally

compensated so the scaling is nearly one to one. The

relationship between the registers is show in Table 43. In Table

44, the relationship between WATTGAIN, VARGAIN and

VAGAIN is given. These relationships can be used for

calibration and simplify the adjustment of VAR and VA gains.

As VAR and VA gains can be deducted from WGAIN, there is

no need to do reactive or apparent gai adjustment.

Table 43. Energy Registers scaling

Line Frequency = 50Hz

Line Frequency = 60Hz

Integrator OFF

VAR = 0.9952 × WATT

VAR = 0.9949 × WATT

VA = 0.9978 × WATT

VA = 1.0015 × WATT

Integrator ON16

VAR = 0.9997 × WATT

VAR = 0.9999 × WATT

VA = 0.9977 × WATT

VA = 1.0015 × WATT

Table 44. Gain compensation adjustments

Line Frequency = 50Hz

Line Frequency = 60Hz

Integrator OFF

VARGAIN = 19.76 +

WGAIN/0.9952

VARGAIN = 21 +

WGAIN/0.9949

VAGAIN = 9.03 +

WGAIN/0.9978

VAGAIN = -60.53 +

WGAIN/1.0015

Integrator ON1

VARGAIN = 1.23 +

VARGAIN = 0.41 +

16 This function is not available in ADE7166 and ADE7566 products

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