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參數(shù)資料
| 型號(hào)： | UCC2974 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | DUAL COLD CATHODE FLUORESCENT LAMP CONTROLLER |
| 中文描述： | 雙冷陰極熒光燈控制器 |
| 文件頁(yè)數(shù)： | 10/12頁(yè) |
| 文件大小： | 210K |
| 代理商： | UCC2974 |
SLUS485A
–
JULY 2001
–
REVISED NOVEMBER 2001
10
www.ti.com
APPLICATION INFORMATION
LFD
–
PWM
LAMP ON
LAMP OFF
DIM
CT
UDG
–
01024
Figure 4. LFD Waveforms
Note from the Figure 4 that the LFD-PWM output is turned on at the start of the discharge cycle and is turned
off when C
T
crosses the DIM signal or at the start of the charge cycle if DIM is less than the valley voltage of
0.5 V.
The LFD oscillator runs free at some frequency determined by the external timing components. The LFD
oscillator can be synchronized to a system clock signal. by applying this clock signal to the LFDSYNC pin. The
signal must not be applied during power up since the MODE pin
’
s crossing of the LFD_ENABLE threshold
determines the function DIM takes on. If the synchronization signal is applied during power up, unpredictable
results may occur. The synchronization frequency should be fairly close to (but higher than) the free run
frequency of the oscillator. The operating range for the DIM signal is reduced when synchronizing the LFD
oscillator just as with any other PWM. A synchronization pulse causes termination of the current charge cycle
and starts a discharge. The ratio of free run to synchronization frequencies is the reduction factor for DIM
’
s
operating range.
For instance if the free-run frequency is 90% of the synchronization frequency, DIM is active over the 0.5-V to
2.75-V range instead of the 0.5-V to 3-V range. As a general recommendation, the free-run frequency should
be kept within the 100-Hz to 1-kHz range, and synchronization should be limited to 120% of the free-run
frequency to preserve control range on DIM.
output driver
The OUT1 and OUT2 pins are designed to directly drive small power MOSFETs. Output drive capability is limited
by the 50-
maximum resistance of the driver. For large FETs where this drive level is insufficient, a separate
driver is required. Note also that the output drive level is limited to approximately 12 V if the input voltage
exceeds that level. For input voltages below 12 V, the driver drives to slightly below the input voltage.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| UCC2974PW | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Texas Instruments 功能描述: |
| UCC2975PW | 功能描述:LCD 驅(qū)動(dòng)器 Multi-Topology Piezoelectric RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時(shí)鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| UCC2975PWG4 | 功能描述:LCD 驅(qū)動(dòng)器 Multi-Topology Piezoelectric RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時(shí)鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| UCC2976PW | 功能描述:LCD 驅(qū)動(dòng)器 Multi-Topology Piezoelectric RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時(shí)鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
| UCC2976PWG4 | 功能描述:LCD 驅(qū)動(dòng)器 Multi-Topology Piezoelectric RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時(shí)鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
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