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| 型号： | MAX17004ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 31/36页 |
| 文件大小： | 0K |
| 描述： | IC PS CTRLR FOR NOTEBOOKS 32TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 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，2 V ~ 5.5 V |
| 工作温度： | -40°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
? ( I LOAD ) R DS ( ON )
V IN ( MAX ) ? ? ? ?
? 1 ? ?
? ?
PD ( N H Re sistive ) = ? OUT ? ( I LOAD DS ( ON )
) 2 R
I LOAD LIMIT ? ?
? Δ I INDUCTOR ?
?
?
? I LOAD Q G ( SW ) C OSS V IN ( MAX ) ?
? V IN ( MAX ) f SW
?
? I GATE ?
lower losses in between. If the losses at V IN(MIN) are
significantly higher, consider increasing the size of N H .
Conversely, if the losses at V IN(MAX) are significantly
higher, consider reducing the size of N H . If V IN does not
vary over a wide range, maximum efficiency is achieved
by selecting a high-side MOSFET (N H ) that has conduc-
tion losses equal to the switching losses.
Choose a low-side MOSFET (N L ) that has the lowest pos-
sible on-resistance (R DS(ON) ), comes in a moderate-sized
package (i.e., 8-pin SO, DPAK, or D 2 PAK), and is reason-
ably priced. Ensure that the MAX17003/MAX17004 DL_
gate driver can supply sufficient current to support the
gate charge and the current injected into the parasitic
drain-to-gate capacitor caused by the high-side MOSFET
turning on; otherwise, cross-conduction problems may
occur. Switching losses are not an issue for the low-side
MOSFET since it is a zero-voltage switched device when
used in the step-down topology.
Power-MOSFET Dissipation
Worst-case conduction losses occur at the duty-factor
extremes. For the high-side MOSFET (N H ), the worst-
case power dissipation due to resistance occurs at mini-
mum input voltage:
? V ?
? V IN ?
Generally, use a small high-side MOSFET to reduce
switching losses at high input voltages. However, the
R DS(ON) required to stay within package power-dissipa-
tion limits often limits how small the MOSFET can be. The
optimum occurs when the switching losses equal the
conduction (R DS(ON) ) losses. High-side switching losses
do not become an issue until the input is greater than
approximately 15V.
Calculating the power dissipation in high-side MOSFETs
(N H ) due to switching losses is difficult, since it must
allow for difficult-to-quantify factors that influence the turn-
on and turn-off times. These factors include the internal
gate resistance, gate charge, threshold voltage, source
inductance, and PC board layout characteristics. The fol-
lowing switching-loss calculation provides only a very
rough estimate and is no substitute for breadboard evalu-
ation, preferably including verification using a thermocou-
ple mounted on N H :
PD ( N H Re sistive ) =
+
2
where C OSS is the output capacitance of N H , Q G(SW) is
the charge needed to turn on the N H MOSFET, and I GATE
is the peak gate-drive source/sink current (1A typ).
Switching losses in the high-side MOSFET can become
a heat problem when maximum AC adapter voltages
are applied, due to the squared term in the switching-
loss equation (C x V IN 2 x f SW ). If the high-side MOSFET
chosen for adequate R DS(ON) at low battery voltages
becomes extraordinarily hot when subjected to
V IN(MAX) , consider choosing another MOSFET with
lower parasitic capacitance.
For the low-side MOSFET (N L ), the worst-case power
dissipation always occurs at maximum battery voltage:
PD ( N L Re sistive ) =
? ? V OUT ? ? 2
?
The absolute worst case for MOSFET power dissipation
occurs under heavy overload conditions that are
greater than I LOAD(MAX) but are not high enough to
exceed the current limit and cause the fault latch to trip.
To protect against this possibility, “overdesign” the cir-
cuit to tolerate:
= I ?
2
where I LIMIT is the peak current allowed by the current-
limit circuit, including threshold tolerance and sense-
resistance variation. The MOSFETs must have a
relatively large heatsink to handle the overload power
dissipation.
Choose a Schottky diode (D L ) with a forward-voltage
drop low enough to prevent the low-side MOSFET’s
body diode from turning on during the dead time. As a
general rule, select a diode with a DC current rating
equal to 1/3rd the load current. This diode is optional
and can be removed if efficiency is not critical.
Boost Capacitors
The boost capacitors (C BST ) must be selected large
enough to handle the gate-charging requirements of
the high-side MOSFETs. Typically, 0.1μF ceramic
capacitors work well for low-power applications driving
medium-sized MOSFETs. However, high-current appli-
cations driving large, high-side MOSFETs require boost
capacitors larger than 0.1μF. For these applications,
select the boost capacitors to avoid discharging the
capacitor more than 200mV while charging the high-
side MOSFETs’ gates:
______________________________________________________________________________________
31
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17005AETP+ | 功能描述:电池管理 1.2MHz High-Perf Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17005AETP+T | 功能描述:电池管理 1.2MHz High-Perf Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17005BETP+ | 功能描述:电池管理 1.2MHz High-Perf Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17005BETP+T | 功能描述:电池管理 1.2MHz High-Perf Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17005DEVKIT+ | 功能描述:电源管理IC开发工具 Programmers, Development Systems RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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