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参数资料
| 型号： | TPS60251RTWR |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHED CAPACITOR CONVERTER, 750 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封装： | 4 X 4 MM, GREEN, PLASTIC, QFN-24 |
| 文件页数： | 3/26页 |
| 文件大小： | 783K |
| 代理商： | TPS60251RTWR |
www.ti.com
OPEN LAMP DETECTION
ENABLING THE DEVICE
ENABLING THE LED BANKS
CAPACITOR SELECTION
I/O INPUT
SETTING THE LED CURRENT
SLVS767C – APRIL 2007 – REVISED NOVEMBER 2007
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 which is 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 TPS60251 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 TPS60251 uses 7 internal comparators to detect when an open LED condition occurs and
shut down the open current sink. The open lamp detection is enabled/disabled using the I2C interface.
The TPS60251 contains a hardware enable input for situations where the IC cannot be disabled using the I2C
interface. Connect the EN input high to enable the device for normal operation. Connect EN low to disable the
device and place it in a low power shutdown. The hardware enable overrides the I2C enable. When EN is pulled
low, the TPS60251 is completely disabled (shutdown mode) and all internal registers are set to 0x00h while the
software shutdown using I2C keeps all internal registers.
The I2C interface is used to enable/disable the LED banks. The MAIN, SUB, and AUX LEDs are individually
controlled. Additionally, the two SUB LEDs (DS_) can be enabled independently.
The TPS60251 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
F. Use of 1-F ceramic capacitors for both chargepump 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 of the 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.
The input logic low and high threshold voltage for I2C interface is changed by supplying voltage to VIO. The
voltage range of VIO is 1.8V to VI. This allows the user to optimize the input logic low and high I
2C threshold
voltages for the TPS60251 to cover different voltage levels for I2C interface for the various phone models.
The maximum LED current is user programmable using the IS input. Connect a resistor from IS to GND to set
the maximum LED current. The resistor value is calculated using the following equation between 2mA and
25.5mA:
Copyright 2007, Texas Instruments Incorporated
11
Product Folder Link(s): TPS60251
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相关代理商/技术参数 |
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| TPS60251RTWRG4 | 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 |
| TPS60251RTWT | 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 |
| TPS60251RTWT | 制造商:Texas Instruments 功能描述:DC/DC Charge Pump Converter IC |
| TPS60251RTWTG4 | 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 |
| TPS60252RTE | 制造商:TI 制造商全称:Texas Instruments 功能描述:HIGH EFFICIENCY CHARGE PUMP FOR 7 WLEDs WITH I2C INTERFACE |
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