LTC7883 datasheet(18/26 Pages) AD

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LTC7883

Rev. 0

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OPERATION

The phase relationships and frequency are independent

of each other, providing numerous application options.

Multiple LTC7883 units/ICs can be synchronized to real-

ize a PolyPhase array. In this case the phases should be

separated by 360/n degrees, where n is the number of

phases driving the output voltage rail.

Serial Bus Addressing

The LTC7883 supports four types of serial bus addressing

schemes to access the individual PWM channels sepa-

rately or jointly.

• Global Bus Addressing

• Power Rail Addressing

• Individual Unit (Device) Addressing

• Page+ Channel Addressing

Each internal unit of the LTC7883 must be given a unique

serial bus address for configuration and control. These

units addresses can be derived from a combination of

external configuration resistors attached to the ASEL

pins and PMBus command values stored in on-board

EEPROM. This method of using ASEL pins to specify

some or all of each unit’s physical address is necessary

when using default factory EEPROM programing, where

both units are assigned to 0x4F. Applying external resistor

configuration for unit addresses is recommended, as it

allows for easier device recovery under a wide range of

programming errors. Refer to the values in Table 7 for full

details on setting each unit address.

Advanced Power Stages

Some LTC7883 factory EEPROM defaults have been

modified from LTC3882-1 values to better accommodate

newer, advanced power stages that provide an output

proportional to load current. Table 3 details these val-

ues. Refer to Figure 1 for an example of interfacing the

LTC7883 to power stages or blocks of this type. If tradi-

tional DCR or discrete resistor sense of output current is

used as shown on the front page, refer to factory EEPROM

defaults given for Table 3 commands in the LTC3882-1

data sheet.

Table 3. Unique LTC7883 Default Factory EEPROM Values

COMMAND NAME

CMD CODE

DESCRIPTION

TYPE

PAGED DATA FORMAT UNITS

DEFAULT VALUE

IOUT_CAL_GAIN

0x38

Ratio of ISENSE ± Voltage

to Sensed Current

R/W Word

L11

mΩ

0.25mΩ

0xAA00

IOUT_OC_FAULT_LIMIT

0x46

Output Overcurrent Fault Limit

R/W Word

L11

70.0A

0xEA30

IOUT_OC_WARN_LIMIT

0x4A

Output Overcurrent Warning Limit

R/W Word

L11

50.0A

0xE320

MFR_IOUT_CAL_GAIN_TC

0xF6

Output Current Sense Element

Temperature Coefficient

R/W Word

ppm/°C

0ppm/°C

0x0000

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