ADM1276-3ACPZ-RL(Rev0) View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

ADM1276-3ACPZ-RL
(Rev.:Rev0)

Hot Swap Controller and Digital Power and Energy Monitoring with PMBus Interface

Analog Devices 

ADM1276

divided by the sense resistor value in ohms to obtain the real-

world power in watts.

There are also two input voltage ranges, thus, there are two sets

of coefficients for converting to and from the power value.

Note the following:

• The same calculations that are used to convert power

values also apply to the energy accumulator value returned

by the READ_EIN command because the energy

accumulator is a summation of multiple power values.

• The READ_PIN_EXT and READ_EIN_EXT commands

return 24-bit extended precision versions of the 16-bit

values returned by READ_PIN and READ_EIN. The direct

format values must be divided by 256 prior to being

converted with the coefficients shown in Table 7.

Example 3. The PIN_OP_WARN_LIMIT command requires a

power limit value expressed in direct format.

If the required power limit is 350 W and the sense resistor is

1 mΩ, the first step is to determine the resistor scaled power

value.

PRESSCALED = P × R

PRESSCALED = 350 × 0.001

PRESSCALED = 0.35

where:

P is the real-world power expressed in watts.

R is the sense resistor value expressed in ohms.

PRESSCALED is the resistor scaled version of power.

Using Equation 1, and working with the 0 V to 20 V range,

Y = ((6043 × 0.35 + 0) × 101

Y = 21,150.5 = 21,151 (rounded up to integer form)

Writing a value of 21,151 with the PIN_OP_WARN_LIMIT

command sets an overpower warning at 350 W.

Table 7. PMBus Conversion to Real-World Coefficients

Coefficient

Current Sense

Voltage

Voltage

0 V to 6 V Range

0 V to 20 V Range

m

807

6720

19,199

b

20,475

0

0

R

−1

−1

−2

Power (Resistor Scaled)

0 V to 6 V Range

0 V to 20 V Range

2115

6043

0

0

+2

+1

Rev. 0 | Page 31 of 48

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