Datasheet
TPS65070, TPS65072, TPS65073
TPS650731, TPS650732, TPS650701, TPS650702, TPS650721
www.ti.com
SLVS950G –JULY 2009–REVISED MAY 2013
OUTPUT VOLTAGE CHANGE FOR LDO1 and LDO2
The output voltage of LDO1 and LDO2 is defined in registers LDO_CTRL1 for LDO1 and in register DEFLDO2
for LDO2. The output voltage can be changed in these registers after power-up.
UNUSED LDOs
In case both LDOS are unused, connect VINLDO1/2 to the SYS node. If VINLDO1/2 is tied to GND, the SYS
voltage will not be turned off during a power-down with only a battery connected and a transit to ON-state is not
posible afterwards.
White-LED BOOST CONVERTER
LED-Current Setting/Dimming
The white LED boost converter generates an output voltage, high enough to drive current through up to 10 white
LEDs connected in series. TPS6507x support one or two strings of white LEDs. If two strings of white LEDs are
used, the number of LEDs in each string is limited to 6LEDs due to the switch current limit as defined in the
electrical characteristics. The boost converter block contains two current sinks to control the current through the
white LEDs. The anodes of the “upper” white-LEDs are directly connected to the output voltage at the output
capacitor. The cathode of the “lowest” LED is connected to the input of the current sink at pin ISINK1 or ISINK2.
The internal current sink controls the output voltage of the boost converter such that there is a minimum voltage
at the current sink to regulate the defined current. The maximum current is set with a resistor connected from pin
ISET1 to GND. Dimming is done with an internal PWM modulator by changing the duty cycle in the current sinks
from 1% to 100%. In order to set a LED current of less than 1% of the current defined at ISET1, a second current
range is set with a resistor at pin ISET2 to GND. By changing between the two current ranges and varying the
duty cycle, it is possible to achieve a dimming ratio of > 1:100. The main functions of the converter like enable /
disable of the converter, PWM duty cycle and dimming frequency are programmed in registers WLED_CTRL1
and WLED_CTRL2 – see the register description for details.
If only one string of white LEDs are used, ISINK1 and ISINK2 need to be connected in parallel.
Setup
In applications not requiring the wLED boost converter, the pins should be tied to a GND as stated below:
Pins L4, FB_wLED, ISINK1 and ISINK2 should be directly connected to GND. Each ISET1 and ISET2 should be
connected to GND with a 100k resistor. Optionally ISET1 and ISET2 can be used as analog inputs to the ADC.
In this case, these pins can be tied to a voltage source in the range from 0V to 2.25V.
Setting the LED Current
There are two resistors which set the default current for the current sinks at ISINK1 and ISINK2.
The resistor connected to ISET1 is used if Bit CURRENT LEVEL is set 1 in register 19h.
The resistor connected to ISET2 is used if Bit CURRENT LEVEL is set 0 in register 19h (default).
This allows switching between two different maximum values for the LED current with one Bit to extend the
resolution for dimming.
Dimming is done by an internal PWM signal that turns on and off the current sinks ISINK1 and ISINK2 at 200Hz
(default). The duty cycle range is 1% to 100% with a 1% resolution and a default duty cycle of 30%. In order to
get the full scale LED current, the PWM dimming needs to be set to 100% in register 19h. This is done by writing
63h to register 19h.
K
ISET
is defined to be 1000 in the electrical spec, the reference voltage at ISET1 and ISET2 is 1.24V.
The current for each string is set by the resistor to:
ISINK1=ISINK2= K
ISET
× 1.24V/R
ISETx
(8) (8)
R
ISET1
, R
ISET2
= K
ISET
× 1.24V/10mA=124 kΩ (9) (9)
A resistor value of 124 kΩ sets the current on each string to 10mA.
For one string of wLEDs, both strings need to be connected in parallel, so the current in the wLEDs is twice the
current programmed by the resistor at ISET1 or ISET2.
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