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參數(shù)資料
| 型號(hào)： | TPS61140DRCT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.26 A SWITCHING REGULATOR, 1500 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | 3 X 3 MM, GREEN, PLASTIC, QFN-10 |
| 文件頁數(shù)： | 4/25頁 |
| 文件大小： | 776K |
| 代理商： | TPS61140DRCT |
www.ti.com
BOTH ON MODE
START UP
OVERVOLTAGE PROTECTION
UNDERVOLTAGE LOCKOUT
THERMAL SHUTDOWN
SLVS624B – JANUARY 2006 – REVISED MARCH 2007
DETAILED DESCRIPTION (continued)
When both the voltage and current outputs are enabled (i.e., SELV high and SELI high), the boost converter
operates in the PWM mode and regulates to the one requiring higher IOUT pin voltage by choosing the smaller of
V(IOUT)–VOUT and V(IFB) as the feedback signal. For example, if voltage regulation requires higher boost output,
V(IOUT)–VOUT is automatically selected as feedback signal for the boost converter. During this time, the IFB pin
voltage is higher than its regulation voltage (VIFB). However, if the IFB pin voltage drops below its regulation
voltage by the IFB low threshold (VIFB_L), the PWM loop switches its feedback path to the IFB pin to ensure the
proper operation of current sink circuit. The same operation occurs if the current output requires higher boost
output. When both V(IOUT)–VOUT and V(IFB) are below their respective low thresholds, the V(IOUT)–VOUT takes
priority as the boost converter's feedback signal.
The overall efficiency in this mode depends on the voltage difference between the current and voltage loads. A
large difference reduces the efficiency due to additional power losses across the linear circuits (i.e., either the
LDO or current sink circuit).
During start up, two feedback loops for the boost converter and linear regulators, are trying to establish steady
state simultaneously. Figure 14 and Figure 15 demonstrate the start up waveform for WLED only and OLED
only outputs.
When only the voltage output is enabled, the Vout ramp time is set by the LDO. The LDO uses an internal RC
circuit to slow down the startup ramp and limit in-rush current. The boost converter output V(IOUT) ramps up with
the LDO output VO maintaining a fixed voltage across the LDO. The boost converter charges both C2 and C3
shown in the block diagram, and the peak inductor current is clamped by the overcurrent limit circuitry.
When only the current output is enabled, Q3 control circuitry ramps up the sink current in 16 steps with each
step taking 64 clock cycles. This soft start mode makes the current sink loop slower than the boost converter’s
loop. Therefore, the boost output can only slowly comes up as the current sink circuitry increases its needed
voltage. This ensures smooth start up and avoids any in rush current.
Soft start is also important for transitioning from voltage only to both on mode. During transition, soft start slowly
adds the load, thereby giving the boost converter enough time to ramp the inductor current and preventing LDO
drop out or VO voltage dip.
To prevent the boost output run away as the result of WLED disconnection, there is an overvoltage protection
(OVP) circuit which stops the boost converter from switching as soon as its output exceeds the OVP threshold.
When the voltage falls below the OVP threshold, the converter resumes switching.
The two OVP options offer the choices to prevent a 25-V rated output capacitor or the internal 30-V FET from
breaking down.
An undervoltage lockout prevents mis-operation of the device for input voltages below 1.65 V (typical). When the
input voltage is below the undervoltage threshold, the device remains off and both the boost converter and linear
circuit are turned off, providing isolation between input and output.
An internal thermal shutdown turns off the IC when the typical junction temperature of 160
°C is exceeded. The
thermal shutdown has a hysteresis of typically 15
°C.
12
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS61140DRCT | 制造商:Texas Instruments 功能描述:IC LED DRVR WT/OLED BCKLT 10-SON 制造商:Texas Instruments 功能描述:IC, LED DRVR WT/OLED BCKLT 10-SON |
| TPS61140DRCTG4 | 功能描述:LED照明驅(qū)動(dòng)器 Dual 700mA Switch 1.2MHz Boost Cnvrtr 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 |
| TPS61140EVM-157 | 功能描述:電源管理IC開發(fā)工具 TPS61140-157 Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| TPS61141 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:DUAL OUTPUT BOOST REGULATOR USING SINGLE INDUCTOR |
| TPS61141DRCR | 功能描述:LED照明驅(qū)動(dòng)器 Dual 700mA Switch 1.2MHz Boost Cnvrtr 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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