Datasheet
LM25066I, LM25066IA
SNVS824C –JUNE 2012–REVISED MARCH 2013
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MFR_SPECIFIC_11: SAMPLES_FOR_AVG (DBh)
The SAMPLES_FOR_AVERAGE is a manufacturer specific command for setting the number of samples used in
computing the average values for IIN, VIN, VOUT, PIN. The decimal equivalent of the AVGN nibble is the power
of 2 samples (e.g. AVGN=12 equates to 4096 samples used in computing the average). The LM25066I/A
supports average numbers of 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096. The SAMPLES_FOR_AVG
number applies to average values of IIN, VIN, VOUT, PIN simultaneously. The LM25066I/A uses simple
averaging. This is accomplished by summing consecutive results up to the number programmed, then dividing by
the number of samples. Averaging is calculated according to the following sequence:
Y = (X
(N)
+ X
(N-1)
+ ... + X
(0)
) / 2
AVGN
(37)
When the averaging has reached the end of a sequence (for example, 4096 samples are averaged), then a
whole new sequence begins that will require the same number of samples (in this example, 4096) to be taken
before the new average is ready.
Table 35. SAMPLES_FOR_AVG Register
AVGN N=2
AVGN
averages Averaging/Register Update Period (ms)
0000 1 1
0001 2 2
0010 4 4
0011 8 8
0100 16 16
0101 32 32
0110 64 64
0111 128 128
1000 256 256
1001 512 512
1010 1024 1024
1011 2048 2048
1100 4096 4096
Note that a change in the SAMPLES_FOR_AVG register will not be reflected in the average telemetry
measurements until the present averaging interval has completed. The default setting for AVGN is 0000 and
therefore the average telemetry will mirror the instantaneous telemetry until a value higher than zero is
programmed.
The SAMPLES_FOR_AVG register is accessed via the PMBus™ read / write byte protocol.
Table 36. SAMPLES_FOR_AVG Register
Value Meaning Default
0h – 0Ch Exponent (AVGN) for number of samples to average over 00h
MFR_SPECIFIC_12: READ_AVG_VIN (DCh)
The READ_AVG_VIN command will report the 12-bit ADC measured input average voltage. If the data is not
ready, the returned value will be the previous averaged data. However, if there is no previously averaged data,
the default value (0000h) will be returned. This data is read with the PMBus™ Read Word protocol. This register
should use the coefficients shown in Table 44.
Table 37. READ_AVG_VIN Register
Value Meaning Default
0h – 0FFFh Average of measured values for input voltage 0000h
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