LTC2972 datasheet(10/112 Pages) LINER

10 / 112 page

LTC2972

2972fa

For more information www.linear.com/LTC2972

ELECTRICAL CHARACTERISTICS

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: All currents into device pins are positive. All currents out of device

pins are negative. All voltages are referenced to GND unless otherwise

specified. If power is supplied to the chip via the VDD33 pin only, connect

VPWR and VDD33 pins together.

Note 3: The ADC total unadjusted error includes all error sources.

First, a two-point analog trim is performed to achieve a flat reference

voltage (VREF) over temperature. This results in minimal temperature

coefficient, but the absolute voltage can still vary. To compensate for this,

a high resolution, drift-free, and noiseless digital trim is applied at the

output of the ADC, resulting in a very high accuracy measurement.

Note 4: Hysteresis in the output voltage is created by package stress

that differs depending on whether IC was previously at a higher or lower

temperature. Output voltage is always measured at 25°C, but the IC is

cycled to 105°C or –40°C before successive measurements. Hysteresis is

roughly proportional to the square of the temperature change.

Note 5: The current sense resolution is determined by the L11 format,

the value of IOUT_CAL_GAIN, and the magnitude of the current being

measured. See Table 3 on page 77 for details.

Note 6: The nominal time between successive ADC conversions (latency of

the ADC) for any given channel is tUPDATE_ADC.

Note 7: VSENSE and ISENSE input currents are characterized by input

current and input differential current. Input current is defined as current

into a single device pin (see Note 2). Input differential current is defined

as (I+ – I–) where I+ is the current into the positive device pin and I– is the

current into the negative device pin.

Note 8: Nonlinearity is defined from the first code that is greater than or

equal to the maximum offset specification to full-scale code, 1023.

Note 9: While READ_VIN operates with 0V ≤ VIN_SNS ≤ 15V, the valid READ_

IIN, READ_PIN, and MFR_EIN operating range is 4.5V ≤ VIN_SNS ≤ 15V.

Note 10: EEPROM endurance and retention are guaranteed by design,

characterization and correlation with statistical process controls. The

minimum retention specification applies for devices whose EEPROM has

been cycled less than the minimum endurance specification.

Note 11: EEPROM endurance and retention will be degraded when

TJ > 105°C.

Note 12: The LTC2972 will not acknowledge any PMBus commands,

except for MFR_COMMON, when a STORE_USER_ALL command is being

executed. See also OPERATION section.

Note 13: Maximum capacitive load, CB, for SCL and SDA is 400pF. Data

and clock rise time (tr) and fall time (tf) are: (20 + 0.1• CB) (ns) < tr < 300ns

and (20 + 0.1 • CB) (ns) < tf < 300ns. CB = capacitance of one bus line in pF.

SCL and SDA external pull-up voltage, VDDIO, is 1.35V < VDDIO < 3.6V.

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TJ = 25°C. VPWR = VIN_SNS = 12V, VDD33 = VDDIO, VDD33, VDD25, REFP and REFM

pins floating, unless otherwise indicated. CVDD33 = 100nF, CVDD25 = 100nF, CVIN_SNS_CAP = 10nF and CREF = 100nF. (Note 2)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

tSP

Pulse Width of Spike Suppressed

(Note 13)

tTIMEOUT_BUS Time Allowed to Complete any

PMBus Command After Which Time

SDA Will Be Released and Command

Terminated

Mfr_config_all_longer_pmbus_timeout = 0

Mfr_config_all_longer_pmbus_timeout = 1

200

280

Additional Digital Timing Characteristics

tOFF_MIN

Minimum Off-Time for Any Channel

100

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