LTC4449 datasheet(31/108 Pages) LINER

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LTC3882-1

Rev A

For more information www.analog.com

OPERATION

Factory Default Operation

The LTC3882-1 ships from the factory with a default con-

figuration stored in its non-volatile memory, unless custom

programming has been requested. These command values

areloadedintovolatileRAMwhenthechipisinitialized.Prior

to receiving any PMBus commands, a stock LTC3882-1 will

operate in the factory default mode. If a STORE_USER_

ALL command is executed, the contents of the non-volatile

memory are replaced with active command values from

internalRAM,andthatwillpermanentlyoverwritethefactory

defaults. Table 5 summarizes the default factory operation

settings of the LTC3882-1 if all resistor configuration pins

are left open. These defaults allow parameters listed in bold

text in the table to be overridden with configuration resistor

programming. Warning limits are given in Table 5 because

exceedingthemwillcausetheALERTpintobeassertedeven

if the PMBus interface is not being utilized.

Table 5. Factory Default Operation Summary

PARAMETER*

DEFAULT SETTING

UNITS

PMBus Address

All writes enabled to Channel 0 at address 0x4F (no PEC).

–

Operation

OPERATION enabled with RUN pin control and soft-off.

–

Input Voltage OFF Threshold

6.0

Input Voltage UV Warning Limit

6.3

Input Voltage ON Threshold

6.5

Input Voltage OV Fault Limit

15.5

Input Voltage OV Fault Response

Latch off.

–

Soft-Start Time

8 (with no delay).

Maximum Start-Up Time (TMAX)

TMAX Fault Response

Retry every 350ms.

–

Output Voltage UV Fault/Warning Limits

0.900/0.925

Output Voltage UV Fault Response

Retry every 350ms.

–

Output Voltage

1.000

Active Voltage Positioning

Disabled.

–

Output Voltage OV Warning/Fault Limits

1.075/1.100

Output Voltage OV Fault Response

Retry every 350ms.

–

Shut Down

8ms soft-off.

–

Output Current Sense Element

0.63mΩ with 3930ppm/°C TC.

–

Output Current OC Warning/Fault Limits

20/29.75

Output Current OC Fault Response

Ignore

–

PWM Switching Mode

Continuous inductor current only.

–

PWM Control Protocol

Three-State PWM.

–

PWM Switching Frequency

500

kHz

Channel 0/1 Phase

0/180

Degrees

Internal Overtemperature Warning/Fault Limits

130/160

°C

Internal Overtemperature Responses

Warning: EEPROM disabled; Fault: PWM disabled.

–

External Undertemperature Fault Limit

–40

°C

External Undertemperature Fault Response

Retry every 350ms.

–

External Overtemperature Warning/Fault Limits

85/100

°C

External Overtemperature Fault Response

Retry every 350ms.

–

FAULT

Asserts low for the following faults: VOUT UV or OV, VIN OV, external or internal OT,

external UT, TON_MAX, or output short cycle.

–

ALERT Masking

ALERTs are masked for loss of PLL lock and external FAULT inputs.

–

*bold entries can be changed with external configuration resistors

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