JMODE/SYNC — Use this jumper to select the mode of operation in a
MODE/SYNC trim part. Connecting a
jumper between pin 1 and 2 sets the IC operation to PFM (pulse frequency
modulation) mode for a higher efficiency at light load. A jumper between pin 2
and pin 3 causes the IC to operate in FPWM (forced pulse width modulation) mode.
By default, the jumper is connected between pin 1 and 2. Pin 1 is indicated by
the dot on the PCB. When evaluating RT trim parts this jumper can be used
to set the switching frequency as long as RMOD is populated and RT is not
populated. With RMOD populated, connecting a jumper between pin 1 and 2 sets the
switching frequency to 2.2 MHz while connecting the jumper between pin 2 and 3
sets the switching frequency to 1 MHz. If the RT resistor is used to set the
switching frequency then RMOD should be depopulated, effectively removing the
JMODE/SYNC jumper.
JEN — This jumper allows
the ENABLE input to be connected to VIN or GND. Connecting a jumper between pin
1 and 2 shorts the ENABLE input to VIN, enabling the part. Connecting a jumper
between pin 2 and 3 shorts the ENABLE input to GND, disabling the part. By
default, this jumper is left open because there is a pullup resistor RENT to VIN
to enable the IC.
JPGOOD — Use this jumper
to select how the PGOOD pin is connected. A jumper between pin 1 and 2 uses Vcc
as the pullup voltage for PGOOD. In this configuration, the PGOOD pin is pulled
up to Vcc through RPG when the output voltage is within regulation. Connecting a
jumper between pin 2 and 3 uses VOUT as the pullup voltage for PGOOD. By
default, this jumper is not populated.