6.5 Limp Home Mode Window
enters the limp-home mode of operation after detecting three consecutive watchdog timeout
events or when the LHSW bit is set high in the SYSCFG1 register. The limp-home mode is programmed by a
variety of registers that sets the operational setpoint. By selecting the
Limp Home
button in the
Devices
Window it will open up the
Limp Home Mode
window. The main
Limp Home Mode
window should now appear
. This window include three sub-windows (
Channel 1
,
Channel 2
, and
Device
). The
channel windows have three slide bars that control
Analog Current
,
On Time
(switching frequency), and
PWM
(internal PWM duty cycle). This is setup similarly to the
Run Mode
windows and adjusts the LHxIADJ registers,
the LHxTON registers, and the LHxPWM registers set-points. Similar to the Channel windows in the Run Mode it
also has selection boxes for
Enable
,
PWM Source
,
PWM 100%
,
Low iLimit Resp
,
High iLimit Resp
, and
Therm Response
.
Device: The window shows a fault timer that is selectable in ms. A check box sets whether the limp home mode
reference point is generated from the LHxIADJ registers for each channel or if the input voltage at the LHI pin
sets the reference voltage for both channels. See the
Detailed Description
section of the
for more detailed information. The
Limp Mode On
button sets the LHSW bit in the SYSCFG1 register.
This allows to turn on the setting put into the Limp Home registers without having
Figure 6-26. GUI, Limp Home Mode Window
An example limp home mode is as follows. The Channels are enabled using the enable box. The PWM source
box is enabled and it sets the PWM duty cycle references to the slide bar for
PWM
, which is the internal PWM
duty cycle control. The PWM duty cycle is set to 512 out of 1024 scale and is therefore a 50% duty cycle. The
On Time
slide bar is set to 7, which is the approximately 440-kHz switching frequency.
Analog Current
is set to
TPS92520EVM-133 Power UP and Operation
SLUUCC4 – OCTOBER 2020
TPS92520EVM-133 Dual 1.6-A Synchronous Buck LED Driver Evaluation
Module
49
Copyright © 2020 Texas Instruments Incorporated
