Datasheet

LTC3880/LTC3880-1
68
3880fc
For more information www.linear.com/LTC3880
PWM CONFIG
COMMAND NAME CMD CODE DESCRIPTION TYPE PAGED
DATA
FORMAT UNITS NVM
DEFAULT
VALUE
MFR_PWM_MODE_
LTC3880
0xD4 Configuration for the PWM engine of each channel R/W Byte Y Reg Y 0xC2
MFR_PWM_CONFIG_
LTC3880
0xF5 Set numerous parameters for the DC/DC controller
including phasing.
R/W Byte N Reg Y 0x10
FREQUENCY_SWITCH 0x33 Switching frequency of the controller R/W Word N L11 kHz Y 350
0xFABC
MFR_PWM_MODE_LTC3880
The MFR_PWM_MODE_LTC3880 command allows the user to program the PWM controller to use Burst Mode operation,
discontinuous (pulse-skipping mode), or forced continuous conduction mode.
BIT MEANING
7 Use High Range of I
LIMIT
0 – Low Current Range
1 – High Current Range
6 Enable Servo Mode
5 Reserved
4 Reserved
3 Reserved
2 Reserved
Bit[1:0] Mode
00b Discontinuous
01b Burst Mode Operation
10b Forced Continuous
Whenever the channel is ramping on, the PWM mode will be discontinuous, regardless of the value of this
command.
Bit [7] of this command determines if the part is in high range or low
range of the IOUT_OC_FAULT_LIMIT command.
Changing this bit value changes the PWM loop gain and compensation. Changing this bit value whenever an output is
active may have detrimental system results.
Bit [6] The LTC3880 will not servo while the part is OFF, ramping on or ramping off. When set to a one, the output servo
is enabled. The output set point DAC will be slowly adjusted to minimize the difference between the READ_VOUT_ADC
and the VOUT_COMMAND (or the appropriate margined value).
This command has one data byte.
MFR_PWM_CONFIG_LTC3880
The MFR_PWM_CONFIG_LTC3880 command sets the switching frequency phase offset with respect to the falling edge
of the SYNC signal. The part must be in the OFF state to process this command. Either the RUN pins must be low or
the part must be commanded off. If the part is in the RUN state and this command is written, the command will be
ignored and a BUSY fault will be asserted. Bits 5 and 6 of this command affect the loop gain of the respective channels
which may require modifications to the external compensation network.
PMBus COMMAND DETAILS