Bit 5: SMM (Single Measure Mode)
When this bit is set, the device performs only one measure and accumulation cycle for the four input channels (normal
scan mode) or four samples of one channel in channel park mode in response to an UPDATE command. The data can
be read by issuing another UPDATE command that moves the previous UPDATE data into the SMBus read registers and
starts another measurement cycle. Data should be read between UPDATE commands. UPDATE commands should be
no less than 500µs apart for reliable measurements. The power accumulators remain at 48-bits even though the single
calculated power is a 28-bit value. After the SMM bit is changed, the UPDATE command should be sent to reset the
accumulators and perform the selected scan operation.
0 = Single-measure mode is disabled.
1 = Single-measure mode is enabled.
Bit 4: PARK_EN
This bit enables the channel park feature. If this bit is set, only one channel is enabled, and the device samples the
selected channel four times faster than the normal round robin rate. The channel to monitor is selected with the PARK0
and PARK1 bits. After the PARK_EN bit is changed, the UPDATE command should be sent to clear out the accumulators
and start a new accumulation period. When the channel park feature is enabled, the minimum time before the power
accumulators can overflow reduces by a factor of four since the selected channel is being updated four times faster. Also,
the power accumulators for the disabled channels do not contain any meaningful data.
0 = Round-robin sampling of all four channels.
1 = One channel is selected (with the PARK0/1 bits).
Bits 3 to 2: PARK1 to PARK0
If the PARK_EN (Park Enable) bit is set, then these bits select which channel is to be monitored at the exclusion of the
other channels.
PARK1 PARK0 SELECTED CHANNEL
0 0 Channel 1
0 1 Channel 2
1 0 Channel 3
1 1 Channel 4
Bit 1: SLOW
This bit is logically OR’ed with the SLOW input pin. If either this bit is set or the SLOW pin is high, then the power accu-
mulation calculation rate is slowed in order to lower the power consumption of the device.
Bit 0: OVF
This status bit is set to a one if any of the power accumulators or the accumulator counter overflows. When the accumula-
tors or counter overflow, they do not roll over. This status bit can be cleared by writing a 0. If any of the power accumula-
tors or the accumulator counter are still full, then this bit immediately sets again. Accumulators and the counter that have
overflowed can be cleared by sending the UPDATE command.
MAX34407 SMBus 4-Channel Wide Dynamic Range
Power Accumulator
www.maximintegrated.com
Maxim Integrated
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