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| 型号： | MAX1533ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 33/38页 |
| 文件大小： | 0K |
| 描述： | IC POWER SUPPLY CONTROLER 32TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 电源控制器 |
| 输入电压： | 4.5 V ~ 26 V |
| 电流 - 电源： | 15µA |
| 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, 5x Output, Main Power-Supply
Controllers for Notebook Computers
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
C BST =
Q GATE
200 mV
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:
where Q GATE is the total gate charge specified in the
high-side MOSFET’s data sheet. For example, assume
the FDS6612A n-channel MOSFET is used on the high
side. According to the manufacturer’s data sheet, a sin-
gle FDS6612A has a maximum gate charge of 13nC
(V GS = 5V). Using the above equation, the required
? ? ( I LOAD ) R DS ( ON )
? ? V ? ?
PD ( N L Re sistive ) = ? 1 - ?
OUT
? V IN ( MAX ) ? ? ?
?
?
2
boost capacitance is:
C BST =
13 nC
200 mV
= 0 . 065 μ F
? ? I INDUCTOR ?
?
?
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 LOAD = I LIMIT - ? ?
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
Selecting the closest standard value. This example
requires a 0.1μF ceramic capacitor.
Applications Information
Duty-Cycle Limits
Minimum Input Voltage
The minimum input operating voltage (dropout voltage)
is restricted by the maximum duty-cycle specification
(see the Electrical Characteristics table). However,
keep in mind that the transient performance gets worse
as the step-down regulators approach the dropout volt-
age, so bulk output capacitance must be added (see
the voltage sag and soar equations in the Design
Procedure section). The absolute point of dropout
occurs when the inductor current ramps down during
the off-time ( ? I DOWN ) as much as it ramps up during
the on-time ( ? I UP ). This results in a minimum operating
voltage defined by the following equation:
V IN ( MIN ) = V OUT + V CHG + h ?
- 1 ? ( V OUT + V DIS )
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.
?
?
1
D MAX
?
?
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:
where V CHG and V DIS are the parasitic voltage drops in
the charge and discharge paths, respectively. A rea-
sonable minimum value for h is 1.5, while the absolute
minimum input voltage is calculated with h = 1.
Maximum Input Voltage
The MAX1533/MAX1537 controllers include a minimum
on-time specification, which determines the maximum
input operating voltage that maintains the selected
switching frequency (see the Electrical Characteristics
table). Operation above this maximum input voltage
results in pulse-skipping operation, regardless of the
operating mode selected by SKIP . At the beginning of
each cycle, if the output voltage is still above the feed-
______________________________________________________________________________________
33
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1533EVKIT | 功能描述:电流和电力监控器、调节器 Evaluation Kit for the MAX1533 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 |
| MAX1534ETE | 功能描述:电流和电力监控器、调节器 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 |
| MAX1534ETE+ | 功能描述:电流和电力监控器、调节器 PS Controllers for for Notebooks 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 |
| MAX1534ETE+T | 功能描述:电流和电力监控器、调节器 PS Controllers for for Notebooks 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 |
| MAX1534ETE-T | 功能描述:电流和电力监控器、调节器 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 |
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