Hi all.

We are integrating ADE7953 into a product of ours. We would like to use it to display the current power consumption (that would be the instantaneous power) and as a second step the energy consumption kW/h. We are communicating with the chip over SPI interface. The two current channels A and B are employed to measure two different loads (single phase, two circuits).

Here is the schematics:

Our procedure is the following:

1. Write to config register: 0x4 (HPFEN bit enabled)

2. Apply optimal settings from datasheet, "REQUIRED REGISTER SETTING", page 18: write 0xAD to reg 0xFE and then write 0x30 to reg 0x120

3. Read regularly (once a sec for example) the meter registers for each channel:

AVA reg -> Papp

AWATT -> Pa

AVAR -> Pr

PFA -> Power factor

ANGLE_A -> Angle

(We map directly the 32/16 bit registers to int32_t/int16_t type)

4. Use apparent power to display the current (instantaneous) consumption by multiplying by some coefficient (we tried to calculate it but we get different results for different loads).

5. We used an external power meter to measure the load and compare the values.

In case of 0 W no load we get:

Papp = 876, Pa = 17 Power factor = 0 Angle = -8

Papp = 876, Pa = -9 Power factor = 0 Angle = -8

Papp = 877, Pa = -8 Power factor = 0 Angle = -8

Papp = 876, Pa = 30 Power factor = 0 Angle = -8

Papp = 876, Pa = 19 Power factor = 0 Angle = -8

Papp = 876, Pa = 6 Power factor = 0 Angle = -8

Papp = 876, Pa = -3 Power factor = 0 Angle = -8

Papp = 876, Pa = 3 Power factor = 0 Angle = -8

Papp = 877, Pa = -5 Power factor = 0 Angle = -8

Papp = 876, Pa = 45 Power factor = 0 Angle = -8

Papp = 876, Pa = -2 Power factor = 0 Angle = -8

Papp = 876, Pa = -9 Power factor = 0 Angle = -8

Papp = 876, Pa = 1 Power factor = 0 Angle = -8

Papp = 875, Pa = 6 Power factor = 0 Angle = -8

Papp = 875, Pa = 22 Power factor = 0 Angle = -8

Papp = 876, Pa = 26 Power factor = 0 Angle = -8

Papp = 876, Pa = 16 Power factor = 0 Angle = -8

Papp = 875, Pa = 29 Power factor = 0 Angle = -8

Papp = 875, Pa = 7 Power factor = 0 Angle = -8

Papp = 876, Pa = 0 Power factor = 0 Angle = -8

Papp = 876, Pa = 21 Power factor = 0 Angle = -8

Papp = 876, Pa = 21 Power factor = 0 Angle = -8

Papp = 876, Pa = -21 Power factor = 0 Angle = -8

Papp = 876, Pa = -8 Power factor = 0 Angle = -8

Papp = 875, Pa = 5 Power factor = 0 Angle = -8

In case of 63.9 W active load (light bulb) we get:

Papp = 3511, Pa = 3486, Power factor = 32535, Angle = -85

Papp = 3522, Pa = 3495, Power factor = 32520, Angle = -101

Papp = 3504, Pa = 3479, Power factor = 32534, Angle = -37

Papp = 3512, Pa = 3460, Power factor = 32288, Angle = -90

Papp = 3536, Pa = 3519, Power factor = 32614, Angle = -68

Papp = 3517, Pa = 3478, Power factor = 32400, Angle = -59

Papp = 3559, Pa = 3524, Power factor = 32452, Angle = -68

Papp = 3500, Pa = 3474, Power factor = 32520, Angle = -73

Papp = 3511, Pa = 3466, Power factor = 32346, Angle = -60

Papp = 3533, Pa = 3502, Power factor = 32479, Angle = -103

Papp = 3518, Pa = 3491, Power factor = 32517, Angle = -80

Papp = 3510, Pa = 3486, Power factor = 32545, Angle = -24

Papp = 3508, Pa = 3480, Power factor = 32502, Angle = -81

Papp = 3524, Pa = 3491, Power factor = 32453, Angle = -104

Papp = 3520, Pa = 3486, Power factor = 32454, Angle = -100

Papp = 3550, Pa = 3506, Power factor = 32361, Angle = -84

Papp = 3542, Pa = 3525, Power factor = 32608, Angle = -47

Papp = 3526, Pa = 3484, Power factor = 32379, Angle = -70

Papp = 3528, Pa = 3508, Power factor = 32584, Angle = -70

Papp = 3533, Pa = 3506, Power factor = 32521, Angle = -102

Papp = 3557, Pa = 3511, Power factor = 32346, Angle = -98

Papp = 3520, Pa = 3489, Power factor = 32480, Angle = -63

Papp = 3514, Pa = 3487, Power factor = 32510, Angle = -120

Papp = 3516, Pa = 3482, Power factor = 32445, Angle = -74

Papp = 3525, Pa = 3500, Power factor = 32539, Angle = -71

Papp = 3502, Pa = 3464, Power factor = 32407, Angle = -73

Papp = 3551, Pa = 3511, Power factor = 32395, Angle = -62

Papp = 3541, Pa = 3511, Power factor = 32483, Angle = -91

Papp = 3528, Pa = 3491, Power factor = 32430, Angle = -57

In case of 1.9 W LED load over switching adapter we get:

Papp = 880, Pa = 38 Power factor = 0 Angle = -323 <-- At this point only the adapter is plugged in

Papp = 880, Pa = 85 Power factor = 0 Angle = -323

Papp = 880, Pa = 78 Power factor = 0 Angle = -323

Papp = 880, Pa = 81 Power factor = 0 Angle = -323

Papp = 879, Pa = 77 Power factor = 0 Angle = -323

Papp = 879, Pa = 91 Power factor = 0 Angle = -323

Papp = 880, Pa = 120 Power factor = 0 Angle = -323 <-- Turn on LED load at this point

Papp = 879, Pa = 139 Power factor = 0 Angle = -323

Papp = 880, Pa = 139 Power factor = 0 Angle = -323

Papp = 880, Pa = 158 Power factor = 0 Angle = -323

Papp = 880, Pa = 145 Power factor = 0 Angle = -323

Papp = 880, Pa = 141 Power factor = 0 Angle = -323

Papp = 880, Pa = 152 Power factor = 0 Angle = -323

Papp = 881, Pa = 157 Power factor = 0 Angle = -323

Papp = 880, Pa = 132 Power factor = 0 Angle = -323

Papp = 880, Pa = 132 Power factor = 0 Angle = -323 <-- Turn off LED at this point

Papp = 880, Pa = 72 Power factor = 0 Angle = -323

Papp = 880, Pa = 63 Power factor = 0 Angle = -323

Papp = 880, Pa = 44 Power factor = 0 Angle = -323

Papp = 880, Pa = 59 Power factor = 0 Angle = -323

Papp = 881, Pa = 53 Power factor = 0 Angle = -323

Papp = 881, Pa = 73 Power factor = 0 Angle = -323

In case of load 13.3 W over transformer we get:

Papp = 1473, Pa = 779 Power factor = 17351 Angle = 728

Papp = 1473, Pa = 752 Power factor = 16729 Angle = 728

Papp = 1473, Pa = 774 Power factor = 17219 Angle = 728

Papp = 1473, Pa = 766 Power factor = 17045 Angle = 728

Papp = 1474, Pa = 746 Power factor = 16593 Angle = 728

Papp = 1474, Pa = 762 Power factor = 16941 Angle = 728

Papp = 1474, Pa = 760 Power factor = 16896 Angle = 728

Papp = 1473, Pa = 777 Power factor = 17289 Angle = 728

Papp = 1473, Pa = 806 Power factor = 17932 Angle = 728

Papp = 1472, Pa = 764 Power factor = 17000 Angle = 728

Papp = 1472, Pa = 769 Power factor = 17133 Angle = 728

Papp = 1471, Pa = 770 Power factor = 17153 Angle = 728

Papp = 1472, Pa = 777 Power factor = 17299 Angle = 728

Papp = 1473, Pa = 762 Power factor = 16955 Angle = 728

Papp = 1472, Pa = 791 Power factor = 17609 Angle = 728

Papp = 1472, Pa = 762 Power factor = 16959 Angle = 728

Papp = 1472, Pa = 769 Power factor = 17124 Angle = 728

Papp = 1472, Pa = 779 Power factor = 17341 Angle = 728

Papp = 1472, Pa = 742 Power factor = 16524 Angle = 728

Papp = 1472, Pa = 784 Power factor = 17462 Angle = 728

Papp = 1473, Pa = 763 Power factor = 16967 Angle = 728

Papp = 1473, Pa = 769 Power factor = 17101 Angle = 728

Papp = 1473, Pa = 776 Power factor = 17275 Angle = 728

We have the following questions:

1. Why do we get Papp ~ 876 when there is no load and what determines this value

2. Are the ripples (the fluctuations of the power) the same described on Page 24 (Figure 44) ?

Because LFP2 does not have an ideal “brick wall” frequency response, the active power signal has some ripple associated with it. This ripple is sinusoidal and has a frequency equal to twice the line frequency. Because the ripple is sinusoidal in nature, it is removed when the active power signal is integrated to compute the active energy (see the Active Energy Calculation section).

If yes how can we get the average value (the dashed line) without these ripples ?

Does this apply for all parameters: active, reactive, apparent ?

3. We are a bit confused with the values of Power factor and Angle

4. We don't understand why in case 3 the Papp does not change when there is adapter and LED attached but the active power changes.

Could you write if we are doing this wrong and what is the best way to do it ?

Regards.

Hi Tsvetan,

First off, in terms of the schematic a couple points:

For reading the power registers, AVA, AWATT, and AVAR, if you need better accuracy then I would recommend reading it a few times over the second and averaging the value.

For the instantaneous current I would recommend reading the IRMS register at least 50 times over a second and averaging the value rather than working back from the AVA value.

One question from me, what gain are you using for the PGA on IA? It can be set from gain of 1 to 22.

Now for your questions:

Best Regards,

David