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參數(shù)資料
| 型號(hào)： | MAX1839 |
| 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)： | 16/26頁 |
| 文件大小： | 444K |
| 代理商： | MAX1839 |
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M
Wide Brightness Range
CCFL Backlight Controllers
16
______________________________________________________________________________________
optimized using R14 and R15 as shown in Figure 7.
The resistor-divider can be used to force commutation
as close to the zero-crossing point as possible.
POR and UVLO
The MAX1739/MAX1839 include power-on reset (POR)
and undervoltage lockout (UVLO) features. The POR
resets all internal registers, such as DAC output, fault
conditions, and all SMBus registers. POR occurs when
VL is below 1.5V. The SMBus input logic thresholds are
designed to meet electrical characteristic limits for VL
as low as 3.5V, but the interface will continue to func-
tion down to the POR threshold.
The UVLO threshold occurs when VL is below 4.2V
(typ) and disables the buck-switch driver.
Low-Power Shutdown
When the MAX1739/MAX1839 are placed in shutdown,
all IC functions are turned off except the 5V linear regu-
lator that powers all internal registers and the SMBus
interface (MAX1739). The SMBus interface is accessi-
ble in shutdown. In shutdown, the linear regulator out-
put voltage drops to about 4.5V and the supply current
is 6μA (typ), which is the required power to maintain all
internal register states. While in shutdown, lamp-out
detection and buck-switch short-circuit detection latch-
es are reset. The device can be placed into shutdown
by either writing to the MODE register (MAX1739
SMBus mode only) or with
SH
/SUS.
Lamp-Out Detection
For safety, during a lamp-out condition, the MAX1739/
MAX1839 limit the maximum average primary-side
transformer voltage (see
Sense Resistors
) and shut
down the lamp after 2s.
The lamp-out detection circuitry monitors V
CSAV
and
shuts down the lamp if V
CSAV
does not exceed 75mV
(typ) within 2 seconds. This circuitry ignores most puls-
es under 200ns. However, in some cases, a small
capacitor is needed at CSAV to prevent noise from trip-
ping the circuitry. This is especially true in noisy envi-
ronments and in designs with marginal layout.
Ideally, the voltage at CSAV is a half-wave rectified sine
wave. In this case, the CSAV lamp-out threshold is as
follows:
I
MIN
= I
MAX
/ 6
where I
MIN
is the CSAV lamp out threshold, and I
MAX
is
the maximum lamp current (see
Sense Resistors
).
Note:
The formulas assume a worst-case CSAV lamp-out
threshold of 100mV and a maximum CSAV average
voltage of 200mV.
Use MINDAC or limit the brightness code to prevent
setting the lamp current below the CSAV lamp-out
threshold.
STATUS1 bit sets when the lamp-out detection circuit
shuts down the device.
Buck-Switch Short Fault Detection
and Protection
When the buck switch (N1) fails short, there is no volt-
age limiting on the transformer and the input forces
excessive voltage on the transformer secondary. This
Figure 6. DPWM Synchronization
MODE
GND
DPWM
SYNCHRONIZATION
SIGNAL
10k
500pF
ADC-
ADC+
SMBus
VL
REF
MAX1739
MAX1839
Figure 7. Adjusting the ZVC Detection
SYNC
R14
R15
R4
R5
REF
CTFB
LX
L1
T1
GND
MAX1739
MAX1839
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PDF描述 |
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| MAX1839EEP | Wide Brightness Range CCFL Backlight Controllers |
| MAX1740 | Digital Signal Processors 144-LQFP |
| MAX1741 | SIM/Smart Card Level Translators in レMAX |
| MAX1740EUB | SIM/Smart Card Level Translators in レMAX |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1839EEP | 功能描述:顯示驅(qū)動(dòng)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 |
| MAX1839EEP+ | 功能描述:顯示驅(qū)動(dòng)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 |
| MAX1839EEP+T | 功能描述:顯示驅(qū)動(dòng)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 |
| MAX1839EEP-T | 功能描述:顯示驅(qū)動(dòng)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 |
| MAX183ACNG | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
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