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参数资料
| 型号： | L6740L |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 模拟信号调理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, PQFP48 |
| 封装： | 7 X 7 MM, 1 MM HEIGHT, HTQFP-48 |
| 文件页数： | 28/44页 |
| 文件大小： | 755K |
| 代理商： | L6740L |
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Output voltage monitoring and protections
L6740L
Typical design considers the intervention of the Average OC before the per-phase OC, leav-
ing this last one as an extreme-protection in case of hardware failures in the external com-
ponents. Typical design flow is the following:
–
Define the maximum total output current (IOC_AVGmax) according to system
requirements
–Set IOC_TH to 35 μA. This implies ROC_TH = 33 kΩ (OC_PHASE pin is fixed to
1.24 V and IOC_TH is the current programmed through ROC_TH).
–Design RG resistor in order to have IINFOx = IOC_TH when IOUT is about 10% higher
than the IOC_AVGmax current. It results:
where N is the number of phases and DCR the DC resistance of the inductors. RG
should be designed in worst-case conditions.
–Design ROC_AVG in order to have the OC_AVG/LI pin voltage to VOC_AVGTH at the
desired maximum current IOC_AVGmax. It results:
where VOC_AVGTH is typically 2.5 V and IOC_AVGmax is the AVG_OC threshold
desired.
–
Adjust the defined values according to bench-test of the application.
–
An additional capacitor in parallel to ROC_AVG can be considered to add a delay in
the protection intervention.
Note:
What previously listed is the typical design flow. In any case, custom design may require
different settings and ratios between the per-phase OC threshold and the AVG OC
threshold. Applications with huge ripple across inductors may required to set IOC_TH to
values higher than 35
μA: in this case the threshold may be increased still keeping I
OC_TH <
50
μA.
7.4.2
NB section
Since the NB section reads the current across low-side MOSFET, it limits the bottom of the
NB inductor current entering in constant current until UV. In particular, since the device limits
the valley of the inductor current, the ripple entity, when not negligible, impacts on the real
OC threshold value and must be considered.
The device detects an over-current condition when the current information IISEN overcomes
the fixed threshold of IOCTH_NB (35μA typ). When this happens, the device keeps the low-
side MOSFET on, also skipping clock cycles, until the threshold is crossed back and IISEN
results being lower than the IOCTH_NB threshold. After exiting the OC condition, the low-side
MOSFET is turned off and the high-side is turned on with a duty cycle driven by the PWM
comparator.
The section enters the quasi-constant-current operation: the low-side MOSFET stays ON
until the current read becomes lower than IOCP_NB skipping clock cycles. The high-side
MOSFET can be then turned ON with a TON imposed by the control loop after the Low-Side
MOSFET turn-off and the section works in the usual way until another OC event is detected.
This means that the average current delivered can slightly increase in quasi-constant-cur-
R
G
1.1 I
OC_AVGmax
() DCR
NI
OCTH
------------------------------------------------------------------
=
R
OC_AVG
V
OC_AVGTH
R
G
I
OC_AVGmax
DCR
------------------------------------------------
=
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相关代理商/技术参数 |
参数描述 |
|---|---|
| L6740LTR | 功能描述:DC/DC 开关控制器 Hybrid controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| L6741 | 功能描述:功率驱动器IC SnglPphase Dual MOSFET Driver RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| L6741TR | 功能描述:功率驱动器IC SnglPphase Dual MOSFET Driver RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| L6743 | 功能描述:功率驱动器IC SnglPphase Dual MOSFET Driver RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| L6743_08 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:High current MOSFET driver |
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