10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
20
40
60
80
100
120
140
I
O
U
T
(
m
A
)
R
ISET
(k )
C012
I
LED
=
2000
î
V
BG
R
ISET
LED Current Sinks
8
LED Current Sinks
8.1
Output Configuration
The TPS61194 or TPS61194-Q1 detects LED output configuration during start-up. Any output connected
to ground is disabled and excluded from adaptive boost control and fault detections. Non-used LED
outputs must be grounded with jumpers J11 through J14.
8.2
Current Setting
Maximum current for the LED outputs is controlled with an external resistor (R4) connected to the ISET
pin. Maximum current can be calculated as follows:
where
•
V
BG
= 1.2 V
•
R
ISET
: current setting resistor (R4), k
Ω
•
I
LED
: output current per output, mA
(3)
Figure 7. Output Current vs R
ISET
8.3
Brightness Control
The TPS61194 or TPS61194-Q1 controls the brightness of the display with conventional PWM. Output
PWM will directly follow the input PWM. Input PWM frequency can be in the range of 100 Hz to 20 kHz.
An external digital PWM signal can be connected to connector J18. For test purposes the PWM input of
the TPS61194 or TPS61194-Q1 can be connected to ground to turn off LEDs or connected to VDDIO/EN
to set up 100% brightness using jumper J2.
9
Fault Detection
9.1
Fault Indicator
The TPS61194 or TPS61194-Q1 has fault detection for LED open and short, V
IN
input overvoltage, VIN
undervoltage lockout, boost overcurrent, and thermal shutdown. Open-drain FAULT pin indicates faults.
Fault pin can be connected to LED D2 for indication (jumper J10).
11
SNVU492 – January 2016
TPS61194xEVM Evaluation Module
Copyright © 2016, Texas Instruments Incorporated