maxq3180-ran Maxim Integrated Products, Inc., maxq3180-ran Datasheet - Page 42

• Manufacturer Part Number: maxq3180-ran
• Description: Low-power, Multifunction, Polyphase Afe
• Manufacturer: Maxim Integrated Products, Inc.

Low-Power, Multifunction, Polyphase AFE
When reading virtual registers, the MAXQ3180 uses the
configurable coefficients TIME_FS, VOLT_FS, AMP_FS,
and PWR_FS to return meaningful data. However, the
user must first configure these coefficients. Table 13
describes how to set the coefficients.
The MAXQ3180 only measures the die temperature
when commanded by the master. To activate tempera-
ture measurement, the master must write one of the
TMPC[1:0] bits in the OPMODE register. When TMPC0
is set to 1, the MAXQ3180 performs a single tempera-
ture conversion by forcing bias currents 1µA and 16µA
through a pair of diode stacks, placing the result in the
RAW_TEMP register and automatically clearing the
TMPC0 bit to 0. When TMPC1 is written to 1, the
MAXQ3180 performs two consecutive temperature con-
versions. The first conversion is the same as previously
stated with 1µA and 16µA bias currents, and the sec-
ond conversion uses reversed 16µA and 1µA bias cur-
rents. The average of the two measurements is placed
in the RAW_TEMP register, and then both TMPC bits
are cleared. Double measurement cancels possible off-
set incidental to single measurement and thus
improves accuracy. The RAW_TEMP register returns
raw ADC sample proportional to absolute temperature.
Conversion to meaningful scale (°F, °C, or °K) should
be done by the master as needed. When finished, the
MAXQ3180 sets the temperature ready flag, TMRD, in
the STATUS1 register. This flag signals an interrupt
request to the master if enabled. The master can then
read the TEMP register and clear the TMRD status flag.
Table 13. Virtual Register Coefficients
42
0x 801–827
0x 831–834
0x 831–834
REGISTER
______________________________________________________________________________________
VIRTUAL
Voltage,
Current,
Power,
Vrms_res = VFS/2
Irms_res = IFS/2
RESOLUTION IN
METER UNITS
E_res = IFS x
(1 LSB)
VFS/2
INPUT
Temperature Measurement
18
30
30
LSB), DEFINED BY
RESOLUTION (1
OUTPUT
USER
P_res
V_res
I_res
VOLT_FS = 2
PWR_FS = 2
AMP_FS = 2
V_res/Vrms_res
The MAXQ3180 should be calibrated at the user’s fac-
tory and the calibration constants stored in nonvolatile
memory by the host microcontroller. Upon any reset or
loss of power, the host microcontroller must reload the
MAXQ3180 with the calibration constants.
The calibration procedure consists of three passes, one
per each phase A, B, and C. Each pass applies the
same calibration procedure to a single phase, consist-
ing of the following items:
• Current Gain Calibration
• Voltage Gain Calibration
• Power Gain Calibration
• Power Linearity Calibration
• Phase Angle Calibration
Each item requires one or more signals be applied to
the meter’s inputs, then the output to be measured. The
calibration coefficients are then calculated, verified,
and loaded into the MAXQ3180’s RAM registers. The
power linearity calibration and the phase angle calibra-
tion can be performed in any order.
To perform the current gain calibration, all three phase
voltages 220V should be applied. Only one current sig-
nal of max amplitude (I
input being calibrated. From the view of the MAXQ3180
pins, the other current inputs should be grounded or
COEFFICIENT
I_res/Irms_res
E_res/P_res
Typical Calibration Procedure
16
16
16
x
x
x
DEFAULT OUTPUT
RESOLUTION
(1 LSB)
Current Gain Calibration
1µA
1µV
MAX
1W
) is applied to the phase
for MAXQ3180
VOLT_FS = 0x81F0
PWR_FS = 0x3539
AMP_FS = 0x17D8
COEFFICIENT
DEFAULT