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參數(shù)資料
| 型號： | TPS61045DRB |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | DIGITALLY ADJUSTABLE LCD BOOST CONVERTER |
| 中文描述： | 數(shù)字可調(diào)液晶Boost變換器 |
| 文件頁數(shù)： | 13/20頁 |
| 文件大?。?/td> | 499K |
| 代理商： | TPS61045DRB |
www.ti.com
VO(step)
19.6 mV
R1
R3
VO
1.233 V
1
R1
R2
CFF
1
2
fs
20
R1
TPS61045
SLVS440A–JANUARY 2003–REVISED SEPTEMBER 2003
APPLICATION INFORMATION (continued)
The output voltage can be digitally programmed by pulling the CTRL pin low for a certain period of time as
described in the
Digital Interface
section. Pulling the signal applied to the CTRL pin low increases or decreases
the DAC output DO (pin 3) one-step where one step is typically 19.6 mV. A voltage step on DO of 19.6mV (typ)
changes the output voltage by one step and is calculated as:
The possible output voltage range is determined by selecting R1, R2 and R3. A possible larger output voltage
range gives a larger output voltage step size. The smaller the possible output voltage range, the smaller the
output voltage step size.
To reduce the overall operating quiescent current in battery powered applications a high impedance voltage
divider must be used with a typical value for R2 of
≤
200 k
and a maximum value for R1 of 2.2 M
.
Some applications may not need the digital interface to program the output voltage. In this case the output DO
can be left open as shown in Figure 18 and the output voltage is calculated as for any standard boost converter:
In such a configuration a high impedance voltage divider must also be used to minimize ground current and a
typical value for R2 of
≤
200 k
and a maximum value for R1 of 2.2 M
are recommended.
A feed-forward capacitor (C
(FF)
), across the upper feedback resistor (R1), is required to provide sufficient
overdrive for the error comparator. Without a feed-forward capacitor or a too small feed-forward capacitor value,
the device shows double pulses or a pulse burst instead of single pulses at the switch node (SW). This can
cause higher output voltage ripple. If a higher output voltage ripple is acceptable, the feedforward capacitor can
be left out too.
The lower the switching frequency of the converter, the larger the feed-forward capacitor value needs to be. A
good starting point is the use of a 10 pF feed-forward capacitor. As a first estimation, the required value for the
feed-forward capacitor can be calculated at the operation point:
with:
R1 = upper resistor of voltage divider
f
S
= switching frequency of the converter at the nominal load current. (For the calculation of the switching
frequency see previous section)
For C
(FF)
choose a value which comes closest to the calculation result.
The larger the feed-forward capacitor, the worse the line regulation of the device. Therefore, the feed-forward
capacitor must be selected as small as possible if good line regulation is of concern.
OUTPUT CAPACITOR SELECTION
For better output voltage filtering a low ESR output capacitor is recommended. Ceramic capacitors have low
ESR values but depending on the application, tantalum capacitors can also be used. Refer to Table 2 and
typical
applications
for the selection of the output capacitor.
Assuming the converter does not show double pulses or pulse bursts on the switch node (SW) the output voltage
ripple is calculated as:
13
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| TPS61045DRBR | 功能描述:LED顯示驅(qū)動器 28-V 85% Eff Boost Converter RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TPS61045DRBRG4 | 功能描述:LED顯示驅(qū)動器 28-V 85% Eff Boost Converter RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TPS61045DRBT | 功能描述:LED顯示驅(qū)動器 28-V 85% Eff Boost Converter RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TPS61045DRBTG4 | 功能描述:LED照明驅(qū)動器 28-V 85% Eff Boost Converter RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| TPS61045EVM-231 | 功能描述:電源管理IC開發(fā)工具 TPS61045-231 Eval Mod 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 |
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