- 您现在的位置：买卖IC网 > PDF目录5131 > MAX8744ETJ+ (Maxim Integrated Products)IC CNTRLR PWR SUP QUAD 32TQFN PDF资料下载
参数资料
| 型号： | MAX8744ETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 28/36页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP QUAD 32TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 6 V ~ 26 V |
| 输出数： | 4 |
| 输出电压： | 3.3V，5V，1 V ~ 26 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 管件 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页当前第28页第29页第30页第31页第32页第33页第34页第35页第36页
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
current to slew faster, replenishing charge removed
from the output filter capacitors by a sudden load step.
The total output voltage sag is the sum of the voltage
sag while the inductor is ramping up, and the voltage
tighter accuracy, but also dissipate more power. Most
applications employ a current-limit threshold (V LIMIT ) of
50mV to 100mV, so the sense resistor may be deter-
mined by:
( )
L Δ I LOAD ( MAX )
(
R CS = =
sag before the next pulse can occur:
2
V SAG =
2 C OUT V IN x D MAX ? V OUT
Δ I LOAD ( MAX ) ( T ? Δ T )
)
+
V LIMIT V ILIM
I LIMIT 10 x I LIMIT
For the best current-sense accuracy and overcurrent
protection, use a 1% tolerance current-sense resistor
between the inductor and output as shown in Figure
C OUT
where D MAX is maximum duty factor (see the Electrical
Characteristics), T is the switching period (1/f OSC ), and
Δ T equals V OUT /V IN x T when in PWM mode, or L x 0.2 x
I MAX /(V IN - V OUT ) when in skip mode. The amount of
overshoot during a full-load to no-load transient due to
stored inductor energy can be calculated as:
7A. This configuration constantly monitors the inductor
current, allowing accurate current-limit protection.
However, the parasitic inductance of the current-sense
resistor can cause current-limit inaccuracies, especially
when using low-value inductors and current-sense
resistors. This parasitic inductance (L SENSE ) can be
canceled by adding an RC circuit across the sense
resistor with an equivalent time constant:
C EQ R 1 = SENSE
V SOAR
≈
( Δ I LOAD ( MAX ) ) 2 L
2 C OUT V OUT
L
R SENSE
Setting the Current Limit
The minimum current-limit threshold must be great
enough to support the maximum load current when the
current limit is at the minimum tolerance value. The
peak inductor current occurs at I LOAD(MAX) plus half
Alternatively, high-power applications that do not
require highly accurate current-limit protection may
reduce the overall power dissipation by connecting a
series RC circuit across the inductor (Figure 7B) with
an equivalent time constant:
I LIMIT > I LOAD ( MAX ) + ? Δ I INDUCTOR ?
R CS = ?
the ripple current; therefore:
? 2 ?
?
?
R 2 ?
R 1 + R 2 ? ?
R DCR
and:
? R 1 + R 2 ?
where I LIMIT_ equals the minimum current-limit thresh-
old voltage divided by the current-sense resistance
(R SENSE_ ). For the default setting, the minimum current-
limit threshold is 45mV.
R DCR =
L ? 1 1 ?
C EQ ? ?
Connect ILIM to LDO5 for a default 50mV current-limit
threshold. In adjustable mode, the current-limit thresh-
old is precisely 1/10 the voltage seen at ILIM. For an
adjustable threshold, connect a resistive divider from
REF to analog ground (GND) with ILIM connected to
the center tap. The external 0.5V to 2V adjustment
range corresponds to a 50mV to 200mV current-limit
threshold. When adjusting the current limit, use 1% tol-
erance resistors and a divider current of approximately
10mA to prevent significant inaccuracy in the current-
limit tolerance.
The current-sense method (Figure 7) and magnitude
determines the achievable current-limit accuracy and
power loss. Typically, higher current-sense limits provide
where R CS is the required current-sense resistance,
and R DCR is the inductor’s series DC resistance. Use
the worst-case inductance and R DCR values provided
by the inductor manufacturer, adding some margin for
the inductance drop over temperature and load.
Output Capacitor Selection
The output filter capacitor must have low enough equiv-
alent series resistance (ESR) to meet output ripple and
load-transient requirements, yet have high enough ESR
to satisfy stability requirements. The output capaci-
tance must be high enough to absorb the inductor
energy while transitioning from full-load to no-load con-
ditions without tripping the overvoltage fault protection.
When using high capacitance, low-ESR capacitors
28
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| GCC15DRAS-S734 | CONN EDGECARD 30POS .100 R/A SLD |
| GBC20DRAI-S734 | CONN EDGECARD 40POS .100 R/A SLD |
| EEC40DRYN-S734 | CONN EDGECARD 80POS DIP .100 SLD |
| RMC22DRYH-S13 | CONN EDGECARD 44POS .100 EXTEND |
| SIP21106DVP-33-E3 | IC REG LDO 3.3V .15A SC75-6 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8744ETJ+ | 功能描述:电流型 PWM 控制器 Quad-Out Main Power Supply Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8744ETJ+T | 功能描述:电流和电力监控器、调节器 Quad-Out Main Power Supply Controller RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8744EVKIT | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY QUAD OUTPUT MAIN - Rail/Tube |
| MAX8744EVKIT+ | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY QUAD OUTPUT MAIN - Rail/Tube |
| MAX8745ETJ+ | 功能描述:电流和电力监控器、调节器 Quad-Out Main Power Supply Controller RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
发布紧急采购，3分钟左右您将得到回复。