LDS8160-002-T2 IXYS, LDS8160-002-T2 Datasheet - Page 25

• Manufacturer Part Number: LDS8160-002-T2
• Description: IC LED DVR WHT/RGB BCKLGT 16WQFN
• Manufacturer: IXYS
• Series: LED-Sense™, Power-Lite™r
• Type: Backlight, White LED, RGB (I²C Interface)r

Specifications of LDS8160-002-T2

• Topology: Linear (LDO), PWM
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: RGB, White LED
• Frequency: 1.2MHz
• Voltage - Supply: 2.3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 16-WQFN, 16-miniQFN
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 25mA
• Internal Switch(s): Yes
• Efficiency: 80%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Details
• Other names: LDS8160-002-T2-2

LDS8160
rating curve. The user operating point must comply
within the specification in Figure 2.
The maximum current of ~ 18mA for the Red LED is
limited by power dissipation at 50
at higher temperatures in respect to the de-rating
specification of Figure A1.2.
The LED Current vs. Temperature curves are then
mapped to LDS8160 Δ PWM duty cycle codes that
are loaded into each of the three LUTs as 32 4-bit
words. Each word can represent from +7 to -7
Δ PWM steps for every 5
The Δ PWM codes are loaded into registers 50h –
7Fh as 4-bit two’s complement values (see Table 7
of main LDS8160 datasheet for code allocation).
To maintain correlation to typical LED vendor data,
the tables establish 25
point. Therefore, “0” is the required  PWM code
value for 25ºC. For temperatures above 25
Δ PWM codes is the delta step change from the 5ºC
temperature point lower than the current step, while
for temperatures below 25
delta step change from the 5ºC temperature higher
then the current step (i.e. closer to 25ºC). The
© 2009 IXYS Corp.
Characteristics subject to change without notice
Figure A1.4: User Chosen Power and De-rating Curve
Figure A1.5: LED Current Correction Curves with
de-rating start at 55
starting at 55
0
C and shutdown at 85
0
C and shutdown at 85
0
0
C as the zero-reference
C temperature
0
C the  PWM code is the
0
C and decreases
increment.
0
C
0
0
C, the
C
25
compensation temperature range is from -35 to 120
Example:
If Δ PWM codes for the Red LED at 35
step) and at 40
be loaded with code 0010 0001 (bin) = 21h.
The LDS8160 has three integrated PWM generators
that allow programming of 256 logarithmic steps with
12-bit resolution in the LOG mode. Each PWM step is
~ 0.17 dB from 300uA to 25mA in the 1-x scale mode
and therefore ~ 0.34 dB in the 2-x scale mode.
1-x scale is typically used in the temperature
correction/compensation part of curve (as shown in
Figure 5) A 2-x scale mode is also available to support
the higher de-rating slope requirements
The LOG mode is required for RGB correction.
Linear mode operation and linear mode LUT correction
codes are an option in WLED applications. If Linear
WLED mode is chosen, all PWM related data for
Dynamic Dimming and Temperature Compensation
are entered as linear step codes, where each Δ PWM
step is 1/256 of full brightness (100% Duty Cycle)
In WLED applications where Linear PWM option mode
is chosen, only one PWM generator is active (i.e. the A
or Blue channel). In Linear mode the PWM is 8-bit
linear resolution where each bit represents is 1/256 of
100% duty cycle.
Example: RGB LUT Table Generation
Assume that the desired nominal forward current at 25
is 15 mA at all three LEDs and the forward voltages for
the R, G,
respectively (per NSSM038AT-E datasheet).
If selected de-rating starts at 50
this
Compensation Curve at Figure 3):
~ 1.2x the nominal value at 25
Red LED;
~ 1.04X the nominal value at 25
mA for Green LED;
~ 1x the nominal value for Blue LED to maintain constant
luminosity over temperature.
Users must also determine the typical forward voltage vs.
Temperature coefficients, or “k” factors, of the LEDs used
@ 1mA of forward current.
For the Nichia NSSM038AT-E these have been
determined as;
- 2.0 mV/
- 1.5 mV/
- 1.3 mV/
Therefore, at 50
V
F
= 2.1V + [-2.0 mV/
temperature
0
0
0
C for RED LED,
C for Green LED, and
C for Blue LED.
B
LEDs are ~
0
0
C 0010 (2 steps), register 77h should
C, forward voltages are
would
0
C x (50
be
0
2.1
0
C - 25
C, i.e. 15 x 1.2 = 18 mA for
Doc. No. 8160_DS, Rev. N1.0
0
0
C, i.e. 15 x 1.04 = 15.6
C, LED current values at
V,
(per
0
C)] =
3.2
the
0
V, and
2.05V for Red
C are 0001 (1
Luminosity
3.2
0
C.
0
V,
C