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LTC2972

2972fa

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MFR_IIN_CAL_GAIN

The MFR_IIN_CAL_GAIN command is used to set the ratio of the voltage at the input current sense pins to the sensed

current. For devices using a fixed current sense resistor, it is the same value as the resistance of the sense resistor

(units are expressed in mΩ). MFR_IIN_CAL_GAIN is internally limited to values between 0.01mΩ to 1,000mΩ. The

Calculations using IIN_CAL_GAIN are:

READ _IIN =

VIIN_SNSPn − VIIN_SNSMn

(MFR _IIN _ CAL _ GAIN) • TCORRECTION

where:

TCORRECTION = [1 + MFR_IIN_CAL_GAIN_TC • 1E-6 • (READ_TEMPERATURE_2 – 25.0)]

Note:

TCORRECTION is limited by hardware to a value between 0.25 and 4.0.

READ_TEMPERATURE_2 is the internal die temperature.

Mfr_ein_config_iin_range[1:0] may be used to minimize noise in systems with low sense resistor values.

MFR_IIN_CAL_GAIN_TC

The MFR_IIN_CAL_GAIN_TC sets the temperature coefficient of the MFR_IIN_CAL_GAIN register value in ppm/°C.

This command uses the internal die temperature.

Refer to MFR_IIN_CAL_GAIN for details on proper usage.

MFR_IIN_CAL_GAIN_TC Data Contents

BIT(S) SYMBOL

OPERATION

b[15:0] Mfr_iin_cal_gain_tc

16-bit twos complement integer representing the temperature coefficient.

Value = Y where Y = b[15:0] is a twos complement number.

Example:

Mfr_iin_cal_gain_tc = 3900ppm

For b[15:0] = 0x0F3C, Value = 3900

MFR_CLEAR_ENERGY

This send byte command clears the accumulated energy and time value in MFR_EIN and can be written even when

the LTC2972 is write-protected with level 2 protection. The LTC2972 may internally delay the application of this

command by up to tUPDATE_ADC, in order to avoid corrupting an ongoing energy calculation.

PMBus COMMAND DESCRIPTION

LTC2972 Datasheet(PDF) 51 Page - Linear Technology