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| 型号： | TPS60250RTE |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 0.65 A SWITCHED CAPACITOR CONVERTER, 750 kHz SWITCHING FREQ-MAX, PQCC16 |
| 封装： | 3 X 3 MM, PLASTIC, QFN-16 |
| 文件页数： | 3/25页 |
| 文件大小： | 762K |
| 代理商： | TPS60250RTE |
LED CURRENT SINKS (DM_, DS_)
OPEN LAMP DETECTION
CAPACITOR SELECTION
SETTING THE LED CURRENT
www.ti.com............................................................................................................................................................ SLVS769C – APRIL 2007 – REVISED APRIL 2008
The TPS60250/2 have constant current sinks which drive seven individual LED current paths. Each current sink
regulates the LED current to a constant value determined by the I2C interface. The internal register addressing
allows the LED main channels DM1~DM5 to be controlled independently from the LED sub channels DS1~DS2.
All LED channels sink up to 25 mA of current except DM5 which has an 80 mA maximum current when
configured as an auxiliary output. Using the I2C interface, the user may assign DM5 to the main display bank with
up to 25 mA current or as an auxiliary output for torch or keypad light or low/weak camera flash with 80 mA
current. DM5 has 64 dimming steps; the same as the main and sub display banks when assigned to the main
display. However, it has its own current programming register and enable control. When assigned as an auxiliary,
DM5 has 4 dimming steps (full scale, 70%, 40%, 20%).
These optimized current sinks minimize the voltage headroom required to drive each LED and maximize power
efficiency by increasing the amount of time the controller stays in 1
× mode before transitioning to 1.5× mode.
In system production it is often necessary to leave LED current paths open depending on the phone model. For
example, one phone may use 2 LEDs to backlight the main display while another uses 4 LEDs. Rather than use
two different ICs for these different phone applications, the TPS60250/2 may be used in both applications with no
additional efficiency loss in the 2 LED applications. In traditional LED driver applications when an LED current
path is open, the current sink voltage falls to ground and the current regulation circuitry drives the output to
maximum voltage in an attempt to regulate the current for the missing LED path. This severely reduces system
efficiency. The TPS60250/2 use 7 internal comparators to detect open lamp condition, when one or more open
LED conditions occur, TPS60250/2 prevent activation of 1.5X mode transition due to missing LEDs. Open lamp
detection is enabled/disabled using the I2C interface.
The TPS60250/2 are optimized to work with ceramic capacitors with a dielectric of X5R or better. The two flying
capacitors must be the same value for proper operation. The 750 kHz switching frequency requires that the flying
capacitor be less than 4.7
F. Use of 1 F ceramic capacitors for both charge pump flying capacitors is
recommended.
For good input voltage filtering, low ESR ceramic capacitors are recommended. A 1
F ceramic input capacitor is
sufficient for most applications. For better input voltage filtering this value can be increased to 4.7
F .
The output capacitor controls the amount of ripple on the output. Since small ripple is undetectable by the human
eye, a 4.7
F output capacitor works well. If better output filtering and lower ripple is desired, a larger output
capacitor may be used.
Figure 14. Dimming Steps for Sub, Main, and Keypad Backlight
Figure 14 shows the dimming steps for sub, main, and auxiliary display banks in a 25 mA maximum current
Copyright 2007–2008, Texas Instruments Incorporated
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS60250RTER | 功能描述:LED照明驱动器 High Eff Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| TPS60250RTERG4 | 功能描述:LED照明驱动器 High Eff Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| TPS60250RTET | 功能描述:LED照明驱动器 High Eff Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| TPS60250RTET | 制造商:Texas Instruments 功能描述:DC/DC Charge Pump Converter IC |
| TPS60250RTETG4 | 功能描述:LED照明驱动器 High Eff Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
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