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參數資料
| 型號： | TPS60251RTWT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩壓器 |
| 英文描述： | SWITCHED CAPACITOR CONVERTER, 750 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封裝： | 4 X 4 MM, GREEN, PLASTIC, QFN-24 |
| 文件頁數： | 2/26頁 |
| 文件大小： | 783K |
| 代理商： | TPS60251RTWT |
www.ti.com
x1 Operating
Area
x1.5 Operating
Area
V
I
V
I
V
O
VA
VF
VDX
CP WLEDDriver
VB
VC
VHYS
LED CURRENT SINKS (DM_, DS_)
SLVS767C – APRIL 2007 – REVISED NOVEMBER 2007
Figure 13. Input Voltage Hysteresis Between
×1 and ×1.5 Mode
As shown in Figure 13, there is input voltage hysteresis voltage between 1
× and 1.5× mode to ensure stable
operation during mode transition. For the 1 cell Li-Ion battery input voltage range, the TPS60251 operates in 1
×
mode when a fully charged battery is installed. Once the battery voltage drops below the VB level, which is the
mode transition voltage from 1
× to 1.5×, the WLED driver operates in 1.5× mode. Once in 1.5× mode, the battery
voltage must rise to the VC level in order to transition from 1.5× to 1×. This hysteresis ensures stable operation
when there is some input voltage fluctuation at the 1
×/1.5× mode transition. The WLED driver provides a typical
280mV hysteresis voltage (VHYS) that changes based on LED current, to prevent oscillating between modes.
The transition voltage, VB, depends on VDX (the mode transition threshold voltage), VF (WLED forward voltage
drop) and VA (the drop out voltage of the charge pump stage) and is calculated as follows:
VB = VA + VF + VDX
VA = ROUT1X × ILEDTOTAL
Where ROUT1X is the 1× mode output impedance of the IC. See the Electrical Characteristics table for output
impedance specifications.
The TPS60251 switches to 1.5
× mode when the input voltage is below V
B and remains in 1.5× mode as long as
the input is lower than VC. 1.5× Mode is exited when the input voltage rises above VC. VC is calculated as:
VC = VF + 550 mV
The input voltage mode transition hysteresis voltage (VHYS) between 1× and 1.5× is calculated using the following
equation.
VHYS = VC – VB = 550 mV – VDX – VA, where VDX = 100 mV
Note that VA is the key factor in determining VHYS and is dependant on the 1× mode charge pump output
impedance and WLED current.
The TPS60251 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 I2C interface. The internal register addressing
allows the LED main channels DM1~DM5 to be controlled independently from the LED sub channels DS1~DS2.
The maximum current is programmable by the user (see the Setting the LED Current section). All the LED
channels sink up to 25mA of current except DM5 which has an 80-mA maximum current when configured as an
10
Copyright 2007, Texas Instruments Incorporated
Product Folder Link(s): TPS60251
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相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 |
| TPS60252RTE | 制造商:TI 制造商全稱:Texas Instruments 功能描述:HIGH EFFICIENCY CHARGE PUMP FOR 7 WLEDs WITH I2C INTERFACE |
| TPS60252RTER | 功能描述:LED照明驅動器 High Eff Charge Pump for 7 WLEDs 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 |
| TPS60252RTERG4 | 功能描述:LED照明驅動器 Hi Eff Charge Pump for 7 WLEDs 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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