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| 型号： | MAX1533AETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 29/38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： | 60 |
| 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： | 管件 |
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High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
The transformer turns ratio (N) is determined by:
where D MAX is the maximum duty factor (see the
N =
V SEC + V FWD
V OUT 5 + V RECT + V SENSE
Electrical Characteristics table), 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 calculat-
( Δ I LOAD ( MAX ) )
where V SEC is the minimum required rectified sec-
ondary voltage, V FWD is the forward drop across the
secondary rectifier, V OUT5(MIN) is the minimum value of
the main output voltage, and V RECT is the on-state volt-
age drop across the synchronous-rectifier MOSFET.
ed as:
V SOAR =
2
2 C OUT V OUT
L
The transformer secondary return is often connected to
I LIMIT LOAD ( MAX ) + ?
? Δ I INDUCTOR ?
?
?
the main output voltage instead of ground to reduce
the necessary turns ratio. In this case, subtract V OUT5
from the secondary voltage (V SEC - V OUT5 ) in the trans-
former turns-ratio equation above. The secondary
diode in coupled-inductor applications must withstand
flyback voltages greater than 60V. Common silicon rec-
tifiers, such as the 1N4001, are also prohibited
because they are too slow. Fast silicon rectifiers such
as the MURS120 are the only choice. The flyback volt-
age across the rectifier is related to the V IN - V OUT5 dif-
ference, according to the transformer turns ratio:
V FLYBACK = V SEC + (V IN - V OUT5 ) x N
where N is the transformer turns ratio (secondary wind-
ings/primary windings), and V SEC is the maximum sec-
ondary DC output voltage. If the secondary winding is
returned to V OUT5 instead of ground, subtract V OUT5
from V FLYBACK in the equation above. The diode ’s
reverse-breakdown voltage rating must also accommo-
date any ringing due to leakage inductance. The
diode’s current rating should be at least twice the DC
load current on the secondary output.
Transient Response
The inductor ripple current also impacts transient-
response performance, especially at low V IN - V OUT dif-
ferentials. Low inductor values allow the inductor
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
sag before the next pulse can occur.
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
the ripple current; therefore:
> I ?
2
where I LIMIT equals the minimum current-limit threshold
voltage divided by the current-sense resistance
(R SENSE ). For the default setting, the minimum current-
limit threshold is 70mV.
Connect ILIM_ to V CC for the default current-limit
threshold. In adjustable mode, the current-limit thresh-
old is precisely 1/10th 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 500mV 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
10μA to prevent significant inaccuracy in the current-
limit tolerance.
The current-sense method (Figure 9) and magnitude
determine the achievable current-limit accuracy and
power loss. Typically, higher current-sense limits pro-
vide tighter accuracy, but also dissipate more power.
( )
L Δ I LOAD ( MAX )
2 C OUT ( V IN × D MAX OUT )
V SAG =
2
- V
Δ I LOAD ( MAX ) ( T - Δ T )
C OUT
+
Most applications employ a current-limit threshold
(V LIMIT ) of 50mV to 100mV, so the sense resistor can
be determined by:
R SENSE = V LIMIT /I LIM
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
______________________________________________________________________________________
29
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1533AETJ+ | 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 |
| MAX1533AETJ+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 |
| MAX1533ETJ | 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 |
| MAX1533ETJ+ | 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 |
| MAX1533ETJ+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 |
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