Linear Technology Analog Devices LTC3882-1, Datasheet

Page: 31 / 108

LTC3882-1
31
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
are loaded into volatile RAM when the chip is initialized. 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
internal RAM, and that will permanently overwrite the factory
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
exceeding them will cause the ALERT pin to be asserted even
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 V
Input Voltage UV Warning Limit 6.3 V
Input Voltage ON Threshold 6.5 V
Input Voltage OV Fault Limit 15.5 V
Input Voltage OV Fault Response Latch off. –
Soft-Start Time 8 (with no delay). ms
Maximum Start-Up Time (TMAX) 10 ms
TMAX Fault Response Retry every 350ms. –
Output Voltage UV Fault/Warning Limits 0.900/0.925 V
Output Voltage UV Fault Response Retry every 350ms. –
Output Voltage 1.000 V
Active Voltage Positioning Disabled. –
Output Voltage OV Warning/Fault Limits 1.075/1.100 V
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 A
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: V
OUT
UV or OV, V
IN
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