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參數(shù)資料
| 型號： | TPS60250RTE |
| 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WLED |
| 文件頁數(shù)： | 11/24頁 |
| 文件大?。?/td> | 419K |
| 代理商： | TPS60250RTE |
www.ti.com
LED CURRENT SINKS (DM_, DS_)
The TPS60250 has constant current sinks which drive seven individual LED current paths. Each current sink
regulates the LED current to a constant value determined by the I
2
C interface. The internal register addressing
allows the LED main channels DM1~DM5 to be controlled independently from the LED sub channels DS1~DS2.
All the LED channels sink up to 25mA of current except DM5 which has an 80-mA maximum current when
configured as an auxiliary output. Using the I
2
C 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 same as 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%).
OPEN LAMP DETECTION
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 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 a
maximum voltage in an attempt to regulate the current for the missing LED path. This severely reduces the
system efficiency. The TPS60250 uses 7 internal comparators to detect when one or more open LED condition
occurs and shut down prevent it from forcing the device to gear up the open current sink. The open lamp
detection is enabled/disabled using the I
2
C interface.
CAPACITOR SELECTION
The TPS60250 is 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
μ
F. Use of 1-
μ
F ceramic capacitors for both chargepump flying capacitors is
recommended.
For good input voltage filtering, low ESR ceramic capacitors are recommended. A 1-
μ
F ceramic input capacitor
is sufficient for most of the applications. For better input voltage filtering this value can be increased.
SETTING THE LED CURRENT
TPS60250
SLVS769–APRIL 2007
APPLICATION INFORMATION (continued)
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.
The output capacitor controls the amount of ripple on the output. Since small ripple is undetectable by the
human eye, a 4.7-
μ
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
11
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| TPS60250RTER | 功能描述:LED照明驅(qū)動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| TPS60250RTERG4 | 功能描述:LED照明驅(qū)動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| TPS60250RTET | 功能描述:LED照明驅(qū)動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| TPS60250RTET | 制造商:Texas Instruments 功能描述:DC/DC Charge Pump Converter IC |
| TPS60250RTETG4 | 功能描述:LED照明驅(qū)動器 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: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
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