lx1689 Microsemi Corporation, lx1689 Datasheet - Page 13

• Manufacturer Part Number: lx1689
• Description: Third Generation Ccfl Controller
• Manufacturer: Microsemi Corporation

Copyright © 2000
Rev. 1.1, 2006-02-27
due to varying input signal amplitude. Input impedance is very
high so BRITE_IN can also be driven from a 100K potentiometer
with no offset error.
BRITE_R and BRITE_OUT Resistor values.
processor. It is a linear current source that varies from 0 to the
current value established at pin BRITE_R multiplied by the DC
voltage at pin BRITE_C. The optimum value for BRITE_R is
usually 10K ohms. The BRITE_OUT voltage range can be scaled
from 300mV to 2.0V.
scaling of BRITE_OUT (including Analog mode BRITE_IN
range) be within 400mV to 1.2V. Maximum voltage correlates to
full brightness settings.
multiplied by the voltage at BRITE_C:
BRITE_OUT and BRITE_R to ground to develop 1.0V to
represent maximum lamp brightness.
BRITE_OUT voltage potential is proportional to BRITE_IN. The
minimum brightness setting at BRITE_IN corresponds to the
minimum voltage at BRITE_OUT. In digital mode, BRITE_IN
has no effect on BRITE_OUT.
E1
SEATING PLANE
In some applications, a precision 10K resistor is connected from
The BRITE_OUT pin is the output from the BRITE_IN signal
PW
TM
V
e
BRITE_OUT
20-Pin Thin Small Shrink Outline (TSSOP)
D
= V
3
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
b
2
However, it is recommended that the
BRITE_C
It is the ratio of the two resistors
1
A1
A2
E
A
(R
BRITE_OUT
L
In Analog mode the
D E S C R I P T I O N ( C O N T I N U E D )
/ R
M E C H A N I C A L D R A W I N G
BRITE_R_
Integrated Products
®
Microsemi
)
c
1
can place other components, such as a thermistor or photo resistor,
at this pin to generate complex functions for controlling brightness.
For example; use a PWM input at the BRITE_IN pin to control
dimming, and boost analog lamp current amplitude at cold lamp
temperature with a thermistor at the BRITE_OUT pin. This will
help warm the lamp faster at start up so final brightness is reached
sooner.
current setting resistor(s) are R7, and R19 and R20 respectively.
The value these resistor(s) are in the range of 200 to 400ohms. The
following formula can be used to determine the current setting
resistor value. Use 1180 for Digital mode and 1260 for analog dim.
In the 1W burst dimming application example shown in figure 2 the
output current is set for nominally 3.5mA. RSNS is calculated
using the formula above as follows:
A standard value of 255 ohms was chosen. It is recommended to
keep the value of the sense resistor in the range of 200 to 400 ohms
as stated above. If calculated value exceeds 400 ohms its best to
increase the value of the R
Because the BRITE_OUT output is a linear current source, you
SETTING THE OUTPUT CURRENT.
Referring to the application examples figures 2 and 3.
R
R
Note:
SNS
SNS
Third Generation CCFL Controller
1. Dimensions do not include mold flash or protrusions;
= 1180 or 1260 x R
= 1180 x 4990 / 3.5 x 6550 = 256.8 ohms
* Lead Coplanarity
these shall not exceed 0.155mm(.006”) on any side.
Lead dimension shall not include solder coverage.
*LC
Dim
Θ1
A1
A2
E1
A
D
E
b
c
e
L
P
RODUCTION
MIN
0.05
0.80
0.19
0.09
6.40
6.25
4.30
0.45
M
0°
-
-
0.65 BSC
ILLIMETERS
BRITE_R
BRITE_OUT
MAX
1.10
0.15
1.05
0.30
0.20
6.60
6.55
4.50
0.75
0.10
D
8°
resistor.
ATA
/ I
OUT
S
HEET
(mA
0.002
0.031
0.007
0.004
0.252
0.246
0.169
0.018
MIN
0°
-
0.026 BSC
-
RMS
I
NCHES
) x R
BRITE_R
0.043
0.006
0.041
0.012
0.008
0.258
0.177
0.030
0.004
0.260
MAX
8°
LX1689
The
Page 13