Minimum

headroom

level

reached

Open LED

fault

Shorted

LED fault

LOW_COMP

MID_COMP

HIGH_COMP

No actions

No actions

DCDC

increases

voltage

Open LED fault when

Shorted LED fault (at

least one output should

be between

LOW_COMP and

MID_COMP)

All outputs are

above headroom

window

DCDC

decreases

voltage

HEADROOM

WINDOW

HIGH_COMP

MID_COMP

LOW_COMP

OUT#

CURRENT/PWM

CONTROL

LOWEST VOLTAGE

SHORT STRING

DETECTION LEVEL

VOLTAGE THRESHOLD

TPS61193-Q1

www.ti.com

SNVSAC7 – OCTOBER 2015

Figure 9. Comparators for Adaptive Voltage Control and LED Fault Detection

Figure 10 illustrates different cases which cause DC-DC voltage increase, decrease, or generate faults. In

normal operation, voltage at all the OUT# pins is between LOW_COMP and MID_COMP levels and boost

When voltage at all the OUT# pins increases above MID_COMP level, DC-DC voltage adapts downwards.

When voltage at any of the OUT# pins falls below LOW_COMP threshold, DC-DC voltage adapts upwards. In

the condition where DC-DC voltage reaches the maximum and there are one or more outputs still below

LOW_COMP level, an open LED fault is detected.

HIGH_COMP level, 6 V typical, is the threshold for shorted LED detection. When the voltage of one or more of

the OUT# pins increases above HIGH_COMP level and at least one of the other outputs is within the normal

headroom window, shorted LED fault is detected.

Figure 10. Protection and DC-DC Voltage Adaptation Algorithms

Copyright © 2015, Texas Instruments Incorporated

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