Datasheet

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LEDONwithReducedCurrent
PWMDimmingSteps = 0.8%, 1.6%, 2.3%, 3.1%, 3.9%, 4.7%, 6.3%, 8.6%
I
TORCH
FREEFREE FREE
I
2
CBus
TC[2:0]=I
DIM=1
TORCH
FREEFREE FREE
LEDOFF
I
TORCH
TC[2:0]=000
DIM=0
TC[2:0]=I
DIM=1
TORCH
TC[2:0]=000
DIM=0
3-BIT ADC
C
IN
VBAT
C
OUT
P
P
L
I
REF
Low-SideCurrentRegulator
P
P
LED
VOUT
+
-
ADC
S/H
3-Bit ADC
ADC[2:0]
START FLASH
10ms
Delay
LEDFAILURE
VOUT-LED<1.5V
WRITEREGISTER2[5:3]=111
ADCDigitalOutputCoding, ADC[2:0]
000:(VOUT-LED)<3.20V
001:3.20V (VOUT-LED)<3.35V≤
010:3.35V (VOUT-LED)<3.50V
011:3.50V (VOUT-LED)<3.65V
100:3.65V (VOUT-LED)<3.80V
101:3.80V (VOUT-LED)<3.95V
110:3.95V (VOUT-LED)<4.10V
111:(VOUT-LED) 4.10V
≤
≤
≤
≤
≤
≥
TPS61050
TPS61052
SLUS525 – MARCH 2007
White LED blinking can be achieved by turning on/off periodically the LED dimmer via the (DIM) bit, see
Figure 40 .
Figure 40. White LED Blinking Control
The TPS6105x device integrates a 3 bit A/D converter to measure the differential voltage across the output and
the low-side current regulator. In order to get a proper settling of the LED forward voltage, the data acquisition is
done approximately 10 ms after the start of the flash sequence.
When running in the linear down-mode (V
F(LED)
< V
IN
), the low-side current regulator drops the voltage difference
between the input voltage and the LED forward voltage. This may result in thermal limitations (especially for
CSP-12 packaging) when running high LED current under high battery conditions (V
IN
≥ 4.5 V) with low forward
voltage LEDs and/or high ambient temperature.
The LED forward voltage measurement can be started either by a START FLASH event (FLASH_SYNC or SFT
bit) or by setting ADC[2:0] bits (whilst MODE_CTRL[1:0]=01 or 10).
Figure 41. LED VF Measurement Principle
22
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