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| 型号： | LT3688EFE#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PDSO24 |
| 封装： | LEAD FREE, PLASTIC, TSSOP-24 |
| 文件页数： | 10/28页 |
| 文件大小： | 415K |
| 代理商： | LT3688EFE#TRPBF |
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LT3688
18
3688f
Low Ripple Burst Mode Operation
To enhance efciency at light loads, the LT3688 operates
in low ripple Burst Mode operation that keeps the output
capacitor charged to the proper voltage while minimizing
the input quiescent current. During Burst Mode opera-
tion, the LT3688 delivers single cycle bursts of current
to the output capacitor followed by sleep periods where
the output power is delivered to the load by the output
capacitor. Because the LT3688 delivers power to the
output with single, low current pulses, the output ripple
is kept below 25mV for a typical application. In addition,
VIN and BIAS quiescent currents are reduced to typically
65μA and 155μA, respectively, during the sleep time. As
the load current decreases towards a no-load condition,
the percentage of time that the LT3688 operates in sleep
mode increases and the average input current is greatly
reduced, resulting in high efciency even at very low loads
(see Figure 5). At higher output loads the LT3688 will be
running at the frequency programmed by the RT resistor,
and will be operating in standard PWM mode. The transi-
tion between PWM and low ripple Burst Mode operation
is seamless, and will not disturb the output voltage. The
front page application circuit will switch at full frequency
at output loads higher than about 60mA.
IL
0.2A/DIV
VSW
5V/DIV
VOUT
10mV/DIV
5μs/DIV
3688 F05
Figure 5. Burst Mode Operation
BST and BIAS Pin Considerations
Capacitor C3 and the internal boost Schottky diodes (see
the Block Diagram) are used to generate boost voltages
that are higher than the input voltage. In most cases, a
0.22μF capacitor will work well. For the best performance
in dropout, use a 1μF or larger capacitor. Figure 6 shows
VIN
BST
SW
BIAS
VIN
VOUT
4.7μF
C3
GND
LT3688
(6a) For VOUT > 2.8V
Figure 6. Three Circuits for Generating the Boost Voltage
VIN
BST
SW
BIAS
VIN
VOUT
4.7μF
C3
D2
GND
LT3688
(6b) For 2.5V < VOUT < 2.8V
VIN
BST
SW
BIAS
VIN
VOUT
4.7μF
C3
GND
LT3688
3688 F06
(6c) For VOUT < 2.5V; VIN(MAX) = 30V
APPLICATIONS INFORMATION
three ways to arrange the boost circuit. The BST pin must
be more than 2.3V above the SW pin for best efciency.
For outputs of 3V and above, the standard circuit (Figure
6a) is best. For outputs between 2.8V and 3V, use a 1μF
boost capacitor. A 2.5V output presents a special case
because it is marginally adequate to support the boosted
drive stage while using the internal boost diode. For reliable
BST pin operation with 2.5V outputs, use a good external
Schottky diode (such as the ON semi MBR0540), and a
1μF boost capacitor (see Figure 6b). For lower output
voltages, the boost diode can be tied to the input (Figure
6c), or to another supply greater than 2.8V. The circuit in
Figure 6a is more efcient because the BST pin current
and BIAS pin quiescent current comes from a lower volt-
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相关代理商/技术参数 |
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| LT3688EUF#PBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3688EUF#TRPBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3688EUFPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 800mA Step-Down Switching Regulator with Power-On Reset |
| LT3688HFE#PBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:MIC23xxx HyperLight Load™ Regulators 标准包装:5,000 系列:HyperLight Load® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.8V 输入电压:2.7 V ~ 5.5 V PWM 型:混合物 频率 - 开关:4MHz 电流 - 输出:2A 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘，8-MLF? 包装:带卷 (TR) 供应商设备封装:8-MLF?（2x2） 产品目录页面:1094 (CN2011-ZH PDF) 其它名称:576-3303-2 |
| LT3688HFE#TRPBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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