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| 型号： | MAX1533AETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 31/38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
V RIPPLE ( P ? P ) = R ESR LOAD ( MAX ) LIR
energy while transitioning from full-load to no-load con-
ditions without tripping the overvoltage fault protection.
When using high-capacitance, low-ESR capacitors (see
the Output-Capacitor Stability Considerations section),
the filter capacitor’s ESR dominates the output voltage
ripple. So the output capacitor’s size depends on the
maximum ESR required to meet the output voltage rip-
ple (V RIPPLE(P-P) ) specifications:
I
In idle mode, the inductor current becomes discontinu-
ous, with peak currents set by the idle-mode current-
sense threshold (V IDLE = 0.2V LIMIT ). In idle mode, the
no-load output ripple can be determined as follows:
selection, the ESR needed to support 25mV P-P ripple is
25mV/1.5A = 16.7m Ω . One 220μF/4V Sanyo polymer
(TPE) capacitor provides 15m Ω (max) ESR. This results
in a zero at 48kHz, well within the bounds of stability.
For low-input-voltage applications where the duty cycle
exceeds 50% (V OUT /V IN ≥ 50%), the output ripple volt-
age should not be greater than twice the internal slope-
compensation voltage:
V RIPPLE ≤ 0.02 x V OUT
where V RIPPLE equals Δ I INDUCTOR x R ESR . The worst-
case ESR limit occurs when V IN = 2 x V OUT , so the
above equation can be simplified to provide the follow-
ing boundary condition:
R ESR ≤ 0.04 x L x f OSC
V RIPPLE ( P ? P ) =
V IDLE R ESR
R SENSE
Do not put high-value ceramic capacitors directly
across the feedback sense point without taking precau-
tions to ensure stability. Large ceramic capacitors can
have a high-ESR zero frequency and cause erratic,
The actual capacitance value required relates to the
physical size needed to achieve low ESR, as well as to
the chemistry of the capacitor technology. Thus, the
capacitor is usually selected by ESR and voltage rating
rather than by capacitance value (this is true of tanta-
lums, OS-CONs, polymers, and other electrolytics).
When using low-capacity filter capacitors, such as
ceramic capacitors, size is usually determined by the
capacity needed to prevent V SAG and V SOAR from
causing problems during load transients. Generally,
once enough capacitance is added to meet the over-
shoot requirement, undershoot at the rising load edge
is no longer a problem (see the V SAG and V SOAR equa-
tions in the Transient Response section). However, low-
capacity filter capacitors typically have high-ESR zeros
that may affect the overall stability (see the Output-
Capacitor Stability Considerations).
Output-Capacitor Stability Considerations
Stability is determined by the value of the ESR zero rel-
ative to the switching frequency. The boundary of insta-
bility is given by the following equation:
unstable operation. However, it is easy to add enough
series resistance by placing the capacitors a couple of
inches downstream from the feedback sense point,
which should be as close as possible to the inductor.
Unstable operation manifests itself in two related but
distinctly different ways: short/long pulses or cycle skip-
ping resulting in a lower switching frequency. Instability
occurs due to noise on the output or because the ESR
is so low that there is not enough voltage ramp in the
output voltage signal. This “fools” the error comparator
into triggering too early or skipping a cycle. Cycle skip-
ping is more annoying than harmful, resulting in nothing
worse than increased output ripple. However, it can
indicate the possible presence of loop instability due to
insufficient ESR. Loop instability can result in oscilla-
tions at the output after line or load steps. Such pertur-
bations are usually damped, but can cause the output
voltage to rise above or fall below the tolerance limits.
The easiest method for checking stability is to apply a
very fast zero-to-max load transient and carefully
observe the output-voltage-ripple envelope for over-
shoot and ringing. It can help to simultaneously monitor
f ESR ≤
where f ESR =
f OSC
π
1
2 π R ESR C OUT
the inductor current with an AC-current probe. Do not
allow more than one cycle of ringing after the initial
step-response under/overshoot.
Input Capacitor Selection
The input capacitor must meet the ripple current
For a typical 300kHz application, the ESR zero frequency
must be well below 95kHz, preferably below 50kHz.
Tantalum and OS-CON capacitors in widespread use at
the time of publication have typical ESR zero frequen-
cies of 25kHz. In the design example used for inductor
requirement (I RMS ) imposed by the switching currents.
For an out-of-phase regulator, the total RMS current in
the input capacitor is a function of the load currents, the
input currents, the duty cycles, and the amount of over-
lap as defined in Figure 10.
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| MAX1533ETJ-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 |
| 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 |
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