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| 型号： | MAX8744AETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/36页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP QUAD 32TQFN |
| 标准包装： | 2,500 |
| 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： | 带卷 (TR) |
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High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
Table 2. Component Suppliers
The MAX8744A/MAX8745A switch-mode power supplies
SUPPLIER
AVX
Central Semiconductor
Fairchild
International Rectifier
KEMET
NEC/Tokin
Panasonic
Philips
Pulse
Renesas
SANYO
Sumida
Taiyo Yuden
TDK
TOKO
Vishay (Dale, Siliconix)
WEBSITE
www.avx.com
www.centralsemi.com
www.fairchildsemi.com
www.irf.com
www.kemet.com
www.nec-tokin.com
www.panasonic.com/industrial
www.philips.com
www.pulseeng.com
www.renesas.com
www.edc.sanyo.com
www.sumida.com
www.t-yuden.com
www.component.tdk.com
www.tokoam.com
www.vishay.com
(SMPS) require a 5V bias supply in addition to the high-
power input supply (battery or AC adapter). This 5V bias
supply is generated by the controller’s internal 5V linear
regulator (LDO5). This bootstrapped LDO allows the
controller to power up independently. The gate-driver
input supply is connected to the fixed 5V linear-regulator
output (LDO5). Therefore, the 5V LDO supply must pro-
vide LDO5 (PWM controller) and the gate-drive power,
so the maximum supply current required is:
I BIAS = I CC + f SW (Q G(LOW) + Q G(HIGH) )
= 5mA to 50mA (typ)
where I CC is 0.7mA (typ), f SW is the switching frequency,
and Q G(LOW) and Q G(HIGH) are the MOSFET data
sheet’s total gate-charge specification limits at V GS = 5V.
SMPS to LDO Bootstrap Switchover
When the 5V main output voltage is above the LDO5
bootstrap-switchover threshold and has completed
soft-start, an internal 1 Ω (typ) p-channel MOSFET
shorts CSL5 to LDO5, while simultaneously shutting
down the LDO5 linear regulator. This bootstraps the
device, powering the internal circuitry and external
Detailed Description
The MAX8744A/MAX8745A standard application circuit
(Figure 1) generates the 5V/5A and 3.3V/5A typical of the
main supplies in a notebook computer. The input supply
range is 7V to 24V. See Table 1 for component selec-
tions, while Table 2 lists the component manufacturers.
The MAX8744A/MAX8745A contain two interleaved,
fixed-frequency, step-down controllers designed for low-
voltage power supplies. The optimal interleaved architec-
ture guarantees out-of-phase operation, reducing the
input capacitor ripple. One internal LDO generates the
keep-alive 5V power. The MAX8744A/MAX8745A have
an auxiliary LDO with an adjustable output for generat-
ing either the 3.3V keep-alive supply or regulating the
low-power 12V system supply.
Fixed 5V Linear Regulator (LDO5)
An internal linear regulator produces a preset 5V low-
current output. LDO5 powers the gate drivers for the
external MOSFETs, and provides the bias supply
required for the SMPS analog controller, reference, and
logic blocks. LDO5 supplies at least 100mA for exter-
nal and internal loads, including the MOSFET gate
drive, which typically varies from 5mA to 50mA,
depending on the switching frequency and external
MOSFETs selected. Bypass LDO5 with a 4.7μF or
greater ceramic capacitor (1μF per 25mA of load) to
guarantee stability under the full-load conditions.
loads from the 5V SMPS output (CSL5), rather than
through the linear regulator from the battery. Boot-
strapping reduces power dissipation due to gate
charge and quiescent losses by providing power from
a 90%-efficient switch-mode source, rather than from a
much-less-efficient linear regulator. The current capa-
bility increases from 100mA to 200mA when the LDO5
output is switched over to CSL5. When ON5 is pulled
low, the controller immediately disables the bootstrap
switch and reenables the 5V LDO.
Reference (REF)
The 2V reference is accurate to ±1% over temperature
and load, making REF useful as a precision system ref-
erence. Bypass REF to GND with a 0.1μF or greater
ceramic capacitor. The reference sources up to 50μA
and sinks 5μA to support external loads. If highly accu-
rate specifications are required for the main SMPS out-
put voltages, the reference should not be loaded.
Loading the reference reduces the LDO5, CSL5
(OUT5), CSL3 (OUT3), and OUTA output voltages
slightly because of the reference load-regulation error.
System Enable/Shutdown ( SHDN )
Drive SHDN below the precise SHDN input falling-edge
trip level to place the MAX8744A/MAX8745A in its low-
power shutdown state. The controller consumes only
8μA of quiescent current while in shutdown mode.
When shutdown mode activates, the reference turns off
after the controller completes the shutdown sequence
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8744AEVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX8744A EVAL KIT - Rail/Tube |
| 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 |
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