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參數資料
| 型號： | TPS61045DRBR |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩壓器 |
| 英文描述： | 0.45 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 3 X 3 MM, GREEN, PLASTIC, SON-8 |
| 文件頁數： | 20/21頁 |
| 文件大小： | 582K |
| 代理商： | TPS61045DRBR |
IN
P(typ)
(LIM)
V
I
= I
+
x 100 ns
L
IN
P(typ)
V
I
= 375 m A +
x 100 ns
L
SLVS440B – JANUARY 2003 – REVISED MARCH 2009
www.ti.com
DETAILED DESCRIPTION
OPERATION
The TPS61045 operates with an input voltage range of 1.8 V to 6 V and generates output voltages up to 28 V.
The device operates in a pulse frequency modulation (PFM) scheme with constant peak current control. This
control scheme maintains high efficiency over the entire load current range and, with a switching frequency of up
to 1 MHz, the device enables the use of small external components.
The converter monitors the output voltage and when the feedback voltage falls below the reference voltage of
1.233 V (typ) the main switch turns on and the current ramps up. The main switch turns off when the inductor
current reaches the internally set peak current of 375 mA (typ). See the peak current control section for more
information. The second criteria that turns off the main switch is the maximum on-time of 6 ms (typ). This limits
the maximum on-time of the converter in extreme conditions. As the switch is turned off, the external Schottky
diode is forward biased delivering the current to the output. The main switch remains off until the minimum off
time of 400 ns (typ) has passed and the feedback voltage is below the reference voltage again. Using this PFM
peak current control scheme, the converter operates in discontinuous conduction mode (DCM) where the
switching frequency depends on the input voltage, output voltage and output current. This gives a high efficiency
over the entire load current range. This regulation scheme is inherently stable which allows a wider range for the
selection of the inductor and output capacitor.
PEAK CURRENT CONTROL
The internal switch is turned on until the inductor current reaches the typical dc current limit (ILIM) of 375 mA. Due
to the internal current limit delay of 100 ns (typ) the actual current exceeds the dc current limit threshold by a
small amount. The typical peak current limit can be calculated:
The higher the input voltage and the lower the inductor value, the greater the current limit overshoot.
SOFTSTART
All inductive step-up converters exhibit high inrush current during start up if no special precautions are taken.
This can cause voltage drops at the input rail during start-up, which may result in an unwanted or premature
system shut down.
When the device is enabled, the internal input switch (Q1) is slowly turned on to reduce the in-rush current
charging the capacitor (C2) connected to pin L. Furthermore, the TPS61045 limits this in-rush current during
start-up by increasing the current limit in two steps starting from ILIM/4 for 256 switch cycles to ILIM/2 for the next
256 switch cycles.
ENABLE (CTRL PIN)
The CTRL pin serves two functions. One is the enable and disable of the device. The other is the output voltage
programming of the device. If the digital interface is not required, the CTRL pin is used as a standard enable pin
for the device.
Pulling the CTRL pin high enables the device beginning with the softstart cycle.
Pulling the CTRL pin to ground for a period of
≥ 560 ms shuts down the device, reducing the shutdown current to
0.1 mA (typ). During shutdown the internal input switch (Q1) remains open and disconnects the load from the
input supply of the device.
This pin must be terminated. For more details on how to use the interface function, see the DIGITAL
INTERFACE (CTRL) section.
8
Copyright 2003–2009, Texas Instruments Incorporated
Product Folder Link(s): TPS61045
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| TPS61045DRBRG4 | 功能描述:LED顯示驅動器 28-V 85% Eff Boost Converter RoHS:否 制造商:Micrel 數位數量:5 片段數量: 安裝風格: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顯示驅動器 28-V 85% Eff Boost Converter RoHS:否 制造商:Micrel 數位數量:5 片段數量: 安裝風格: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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
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| TPS61046EVM-682 | 功能描述:TPS61046 - DC/DC, Step Up 2, Non-Isolated Outputs Evaluation Board 制造商:texas instruments 系列:- 零件狀態:有效 主要用途:DC/DC，步升 輸出和類型:2，非隔離 功率 - 輸出:- 電壓 - 輸出:12V，5 V ~ 28 V 電流 - 輸出:100mA，20mA 電壓 - 輸入:1.8 V ~ 5.5 V 穩壓器拓撲:升壓 頻率 - 開關:1MHz 板類型:完全填充 所含物品:板 使用的 IC/零件:TPS61046 標準包裝:1 |
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