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参数资料
| 型号： | LP3906SQXVPFP |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 2 A DUAL SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, QCC24 |
| 封装： | 5 X 4 MM, 0.80 MM HEIGHT, LLP-24 |
| 文件页数： | 29/40页 |
| 文件大小： | 4197K |
| 代理商： | LP3906SQXVPFP |
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MODE BOUNCE
PFM-PWM transition at low load current.
To improve efficiency at lower load currents LP3906 buck
converters employ an automatically invoked PFM mode for
the low load operation. The PFM mode operates with a much
lower value quiescent current (I
Q) than the PWM mode of op-
eration that is used in the higher load currents.
As shown in the datasheet section about SW operation, there
is a DC voltage difference between the two modes of opera-
tion, with Vout PFM being typically 1.2% higher than Vout
PWM. So there is a DC voltage level transition and some as-
sociated dynamic perturbation at the mode transition point.
The transition between the two modes of operation has an
associated hysterisis in the transition current value, That is,
the transition point for increasing current (PFM to PWM) is at
a higher value that the decreasing current (PWM to PFM).
This hysterisis is to ensure that in the event that the load cur-
rent values equals the PFM PWM transition value, the device
will not make multiple transitions between modes; this re-
duces the noise at this load by eliminating multiple transitions
between modes (also known as mode bounce).
Under some conditions of high Vin and Low Vout the hystersis
value is reduced and some amount of mode bounce can oc-
cur. Under these conditions, the regulator still maintains DC
regulation, however the output ripple is more pronounced.
Refer to the attached Vout vs Vin chart below that shows the
operational area that may exhibit this increased output ripple.
If the application is expected to be operated in the area of
concern AND have a static load current of the transition cur-
rent value, the user can avoid the possible noise increase by
invoking the components’ “Force PWM mode”.
LP3906 Buck Converter
V
OUT vs VIN Operating Range
during PFM-PWM-PPM Transition
20197865
35
www.national.com
LP3906
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|---|---|
| LP3906SQXPPXP | 2 A DUAL SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, QCC24 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LP3906SQX-VPFP/NOPB | 功能描述:其他电源管理 RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| LP3907 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Dual High-Current Step-Down DC/DC and Dual Linear Regulator with I2C Compatible Interface |
| LP3907QSQ-JJXP/NOPB | 功能描述:上下转换器 Dual Hi-Current SD DC/DC RoHS:否 制造商:Texas Instruments 产品:Down Converters 射频:52 MHz to 78 MHz 中频:300 MHz LO频率: 功率增益: P1dB: 工作电源电压:1.8 V, 3.3 V 工作电源电流:120 mA 最大功率耗散:1 W 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PQFP-128 |
| LP3907QSQ-JXI7/NOPB | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| LP3907QSQ-JXIP/NOPB | 功能描述:上下转换器 Dual Hi-Current SD DC/DC RoHS:否 制造商:Texas Instruments 产品:Down Converters 射频:52 MHz to 78 MHz 中频:300 MHz LO频率: 功率增益: P1dB: 工作电源电压:1.8 V, 3.3 V 工作电源电流:120 mA 最大功率耗散:1 W 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PQFP-128 |
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