參數(shù)資料
型號(hào)： TPS60251RTW
廠商： Texas Instruments, Inc.
英文描述： HIGH EFFICIENCY CHARGE PUMP FOR 7 WLEDs WITH I2C INTERFACE
中文描述： 高效電荷泵7，帶有I2C接口個(gè)WLED
文件頁(yè)數(shù)： 10/28頁(yè)
文件大?。?/td> 515K
代理商： TPS60251RTW
www.ti.com
APPLICATION INFORMATION
APPLICATION OVERVIEW
Most of the current handsets fall into one of three categories. First is the clamshell design, with a main display
on the inside, a secondary display on the outside and a keypad backlight. Second is the bar design, with a main
display and a keypad backlight. Third is the slide type (slide-up and slide-down) design, with a main display and
two keypad banks (inside and outside). The TPS60251 is well suited for use in these three major phone designs
because it has 7 individually regulated white LED current paths for driving up to five white LEDs in main display
and up to two white LEDs in sub display with regulated constant current for uniform intensity. The main and sub
display LED channels drive up to 25mA and an auxiliary LED output (DM5) drives up to 80mA that can be
assigned for keypad backlight, torch light or low cost/weak camera flash application using the I
2
C interface.
OPERATING PRINCIPLE
Charge pumps are becoming increasingly attractive in battery-operated applications where board space and
maximum height of the converter are critical constraints. The major advantage of a charge pump is the use of
only capacitors as storage elements. The TPS60251 chargepump provides regulated LED current from a 3-V to
6-V input source. It operates in two modes. The 1
×
mode, where the input is connected to the output through a
pass element, and a high efficiency 1.5
×
charge pump mode. The IC maximizes power efficiency by operating in
1
×
and 1.5
×
modes as input voltage and LED current conditions require. The mode of operation is automatically
selected by comparing the forward voltage of the WLED plus the voltage of current sink for each LED with the
input voltage. The IC starts up in 1
×
mode, and automatically transitions to 1.5
×
if the voltage at any current sink
input (DM_or DS_) falls below the 100-mV transition voltage. The IC returns to 1
×
mode as the input rises.
Figure 13
provides a visual explanation of the 1
×
to 1.5
×
transition.
In 1.5
×
mode, the internal oscillator determines the charge/discharge cycles for the flying capacitors. During a
charge cycle, the flying capacitors are connected in series and charged up to the input voltage. After the on-time
of the internal oscillator expires, the flying capacitors are reconfigured to be in parallel and then connected in
series to the input voltage. This provides an output of 1.5
×
the input voltage. After the off-time of the internal
oscillator expires, another charge cycle initiates and the process repeats.
TPS60251
SLVS767–APRIL 2007
The TPS60251 circuit uses only 5 external components: the input/output capacitors, 2 chargepump flying
capacitors, and one resistor that sets the maximum WLED current. The few external components combined with
the small 4mm
×
4mm QFN package provide for a small total solution size. By combining independent control of
three separate banks of backlight LEDs with low cost and weak flash capability, the TPS60251 helps designers
minimize power consumption especially in light load conditions while reducing component count and package
size.
10
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TPS60251RTWR 功能描述:LED照明驅(qū)動(dòng)器 High Eff Charge Pump 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
TPS60251RTWRG4 功能描述:LED照明驅(qū)動(dòng)器 High Eff Charge Pump 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
TPS60251RTWT 功能描述:LED照明驅(qū)動(dòng)器 High Eff Charge Pump 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
TPS60251RTWT 制造商:Texas Instruments 功能描述:DC/DC Charge Pump Converter IC
TPS60251RTWTG4 功能描述:LED照明驅(qū)動(dòng)器 High Eff Charge Pump 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
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