參數(shù)資料
型號: MAX1739
廠商: Maxim Integrated Products, Inc.
英文描述: Wide Brightness Range CCFL Backlight Controllers
中文描述: 寬亮度范圍CCFL背光控制器
文件頁數(shù): 14/26頁
文件大?。?/td> 444K
代理商: MAX1739
M
Wide Brightness Range
CCFL Backlight Controllers
14
______________________________________________________________________________________
brightness code of ob00000 corresponds to a 9.375%
DPWM duty cycle, and a brightness code of ob11111
corresponds to a 100% DPWM duty cycle. The duty
cycle changes by 3.125% per step, except codes
ob00000 to ob00011 all produce 9.375% (Figure 3).
To disable DPWM and always use 100% duty cycle, set
V
MINDAC
to VL. Note that with DPWM disabled, the
equations above should assume V
MINDAC
= 0 instead
of V
MINDAC
= VL. Table 2 lists MINDAC
s functionality,
and Table 3 shows some typical settings for the bright-
ness adjustment.
In normal operation, V
MINDAC
is set between 0 and
V
REF
, and the MAX1739/MAX1839 use both lamp cur-
rent control and DPWM control to vary the lamp bright-
ness (Figure 4). In this mode, lamp current control
regulates the average lamp current during a DPWM on-
cycle and not the overall average lamp current.
Analog Interface and Brightness Code
The MAX1739/MAX1839 analog interface uses an inter-
nal ADC with 1-bit hysteresis to generate the brightness
code used to dim the lamp (see
Dimming Range
).
CTL/SDA is the ADC
s input, and CRF/SCL is its refer-
ence voltage. The ADC can operate in either positive-
scale ADC mode or negative-scale ADC mode. In
positive-scale ADC mode, the brightness code increas-
es from 0 to 31 as V
CTL
increases from 0 to V
CRF
. In
negative-scale mode, the brightness scale decreases
from 31 to 0 as V
CTL
increases from 0 to V
CRF
(Figure 5).
The analog interface
s internal ADC uses 1-bit hystere-
sis to keep the lamp from flickering between two codes.
V
CTL
s positive threshold (V
CTL(TH)
) is the voltage
required to transition the brightness code as V
CTL
increases and can be calculated as follows:
V
CTL(TH)
= (n + 2) / 33 V
CRF
(positive-scale ADC mode, MODE = GND)
V
CTL(TH)
= (33 - n) / 33 V
CRF
(negative-scale ADC mode, MODE = REF)
where n is the current selected brightness code. V
CTL
s
negative threshold is the voltage required to transition
the brightness code as V
CTL
decreases and can be
calculated as follows:
V
CTL(TH)
= n / 33 V
CRF
(positive-scale ADC mode, MODE = GND)
V
CTL(TH)
= (31 - n) / 33 V
CRF
(negative-scale ADC mode, MODE = REF)
Figure 5 shows a graphic representation of the thresh-
olds. CRF/SDA
s and CTL/SCL
s input voltage range is
2.7V to 5.5V.
MINDAC = VL
DPWM disabled (always on 100% duty cycle). Operates in lamp current control only.
(Use V
MINDAC
= 0 in the equations.)
MINDAC = REF
DPWM control enabled, duty cycle ranges from 9% to 100%. Lamp current control is disabled
(always maximum current).
0
V
MINDAC
< VREF
The device uses both lamp current control and DPWM.
Table 2. MINDAC Functionality
0
10
20
30
60
70
40
50
80
90
100
0
12
4
8
20
16
24
28
32
BRIGHTNESS CODE
D
DPWM SETTINGS
Figure 3. DPWM Settings
0
10
20
30
60
70
40
50
80
90
100
0
12
4
8
20
16
24
28
32
BRIGHTNESS CODE
C
COMBINED POWER LEVEL
(BOTH DPWM AND
LAMP CONTROL CURRENT)
Figure 4. Combined Power Level
相關(guān)PDF資料
PDF描述
MAX1739-MAX1839 Wide Brightness Range CCFL Backlight Controllers
MAX1739EEP Wide Brightness Range CCFL Backlight Controllers
MAX1839 Wide Brightness Range CCFL Backlight Controllers
MAX1839EEP Wide Brightness Range CCFL Backlight Controllers
MAX1740 Digital Signal Processors 144-LQFP
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1739EEP 功能描述:顯示驅(qū)動器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX1739EEP+ 功能描述:顯示驅(qū)動器和控制器 CCFL Backlight Controller RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX1739EEP+T 功能描述:顯示驅(qū)動器和控制器 CCFL Backlight Controller RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX1739EEP-T 功能描述:顯示驅(qū)動器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX1739EVKIT 功能描述:電源管理IC開發(fā)工具 MAX1739 Eval Kit RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V