RT5735
I2C Interface Function
Force PWM Mode : In the COMMAND register
PWMSEL0 and PWMSEL1 can decide converter is
always at PWM mode or enters power saving mode at
light load condition. During output voltage is changed
from high to low at light load, setting DVSMODE bit to 1
will make transition operate at PWM mode and output
voltage will decrease quickly. If setting to 0, the output
voltage will decrease depending on the loading.
RT5735 can be used by I2C interface to select VOUT
voltage level, over current limit level, thermal warning
temperature level, PWM control mode, and so on. The
register of each function can be found from the following
register map and it also explains how to use these
function.
VOUT Selection : RT5735 has external VSEL pin to
select PROGVSEL1(0X10) or PROGVSEL0(0X11)
which can control VOUT from 0.6V to 1393.75mV with
7bits resolution. Pull VSEL to high is for PROGVSEL1
and pull VSEL to low is for PROGVSEL0. If VSELGT bit
in the COMMAND register is set to 0, VOUT will only be
controlled by PROGVSEL1.
Over Current Level : RT5735 has four levels of over
current limit to be selected. Using IOC bits in the
LIMCONF register can change different inductor valley
current limit level.
Thermal Shutdown Protection : The default REARM
bit in the LIMCONF register is 1. RT5735 will shut down
switching operation when the junction temperature
exceeds 150°C. Once the junction temperature cools
down by approximately 30°C the IC will resume normal
operation with a complete soft-start. When REARM bit
is set to 0, once the device triggers the OTP, the system
will be latched and the output voltage will no longer be
regulated during OTP latched state. Re-start input
voltage or EN pin can unlatch the protection state.
Using I2C to shutdown the system and then re-enable it
will also unlatch UVP function.
Discharge Function : In the PGOOD register DISCHG
bit is set to 1 can let VOUT discharge by internal resistor
when converter shuts down. If setting to 0 VOUT will
decrease depending on the loading.
Power Good Function : In the PGOOD register
PGDCDC bit can control if external PG pin is active.
After PG function is active if PGDVS pin is 0, PG will not
change state during VOUT changing. Once PGDVS pin
is 1 PG will be low when VOUT is much lower than VREF
during VOUT changing.
Slew Rate Setting : RT5735 can control slew rate as
VOUT changing between two voltage levels for both up
and down. In the time register DVS_UP bits can control
up-speed when in the LIMCONF register DVS_DOWN
can control down-speed. DVS_DOWN is valid only
when converter is at PWM mode or DVSMODE bit is 1.
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation
www.richtek.com
12
DS5735-00 August 2014
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
