- 您现在的位置：买卖IC网 > PDF目录1837 > MAX1531ETJ/V+T (Maxim Integrated Products)IC PS CTRLR MULTI-OUTPUT 32WQFN PDF资料下载
参数资料
| 型号： | MAX1531ETJ/V+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 24/33页 |
| 文件大小： | 0K |
| 描述： | IC PS CTRLR MULTI-OUTPUT 32WQFN |
| 标准包装： | 2,500 |
| 应用： | 五路电源监控器 |
| 电源电压： | 4.5 V ~ 28 V |
| 电流 - 电源： | 1.7mA |
| 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) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页当前第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页
Multiple-Output Power-Supply
Controllers for LCD Monitors
VL and AGND at ILIM. The threshold is approximately
1/5th the voltage on ILIM over a range of 0.25V to 3V:
I VALLEY × R DS ( ON )_ HOT < 0 . 2 × V ILIM × ( 1 ? K )
the voltage drop across the capacitor’s ESR caused by
the current into and out of the capacitor:
V RIPPLE = V RIPPLE ( ESR ) + V RIPPLE ( C )
V RIPPLE ( ESR ) = I RIPPLE × R ESR
K is the accuracy of the current-limit threshold, which is
20% when the threshold is 250mV.
V RIPPLE ( C ) =
I RIPPLE
8 × C OUT × f SW
For example, Figure 1’s N1 MOSFET has a maximum
R DS(ON) at room temperature of 145m Ω and an esti-
mate of its maximum at our chosen maximum tempera-
ture of +85°C is 188m Ω . Since the inductor ripple
current is 0.5A, the valley current through the MOSFET
is 1.25A. So the maximum valley current-sense signal is
235mV, which is too high to work with the 190mV mini-
mum of the default current-limit threshold. Adding a
divider at ILIM (R12 and R13) adjusts the ILIM voltage to
1.7V and the current-limit threshold to 340mV, providing
more than adequate margin for threshold accuracy.
Input Capacitor
The input filter capacitor reduces peak currents drawn
from the power source and reduce noise and voltage
ripple on the input caused by the regulator’s switching.
It is usually selected according to input ripple current
requirements and voltage rating, rather than capaci-
tance value. The input voltage and load current deter-
mine the RMS input ripple current (I RMS ):
where C OUT is the output capacitance, and R ESR is the
ESR of the output capacitor. In Figure 1’s circuit, the
inductor ripple current is 0.5A. Assume the voltage-rip-
ple requirement is 2% (peak-to-peak) of the 3.3V out-
put, which corresponds to 66mV total peak-to-peak
ripple. Assuming that the ESR ripple component and
the capacitive ripple component each should be less
than 50% of the 66mV total peak-to-peak ripple, then
the ESR should be less than 66m Ω and the output
capacitance should be more than 7.6μF to meet the
total ripple requirement. A 22μF ceramic capacitor with
ESR (including PC board trace resistance) of 10m Ω is
selected for the standard application circuit in Figure 1,
which easily meets the voltage ripple requirement.
The step-down regulator’s output capacitance and ESR
also affect the voltage undershoot and overshoot when
the load steps up and down abruptly. The undershoot
and overshoot have three components: the voltage
steps caused by ESR, the voltage undershoot and
overshoot due to the current-mode control’s AC load
I RMS = I LOAD ×
V OUT × ( V IN ? V OUT )
V IN
regulation, and the voltage sag and soar due to the
finite capacitance and inductor slew rate.
The amplitude of the ESR steps is a function of the load
The worst case is I RMS = 0.5 × I LOAD , which occurs at
V IN = 2 × V OUT .
For most applications, ceramic capacitors are used
because of their high ripple current and surge current
capabilities. For long-term reliability, choose an input
capacitor that exhibits less than +10 ° C temperature
rise at the RMS input current corresponding to the max-
imum load current.
Output Capacitor
The output capacitor and its equivalent series resis-
step and the ESR of the output capacitor:
V ESR _ STEP = Δ I LOAD × R ESR
The amplitude of the sag due to the finite output capac-
itance and inductor slew rate is a function of the load
step, the output capacitor value, the inductor value, the
input-to-output voltage differential, and the maximum
duty cycle:
tance (ESR) affect the regulator’s loop stability, output
ripple voltage, and transient response. The
Compensation Design section discusses the output
V SAG _ LC =
L × ( Δ I LOAD ) 2
2 × C OUT × ( V IN ( MIN ) × D MAX - V OUT )
capacitance requirement based on the loop stability.
This section deals with how to determine the output
capacitance and ESR needs according to the ripple
voltage and load transient requirements.
The output voltage ripple has two components: varia-
tions in the charge stored in the output capacitor, and
The amplitude of the undershoot due to the AC load
regulation is a function of the high-side MOSFET
R DS(ON) , the gain of the current-sense amplifier A VCS ,
the change of the slope compensation during the under-
shoot ( Δ SC UNDER ), the transconductance of the error
24
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1533AETJ+ | IC POWER SUPPLY CONTROLER 32TQFN |
| MAX1533ETJ+ | IC POWER SUPPLY CONTROLER 32TQFN |
| MAX1534ETE+ | IC PWR SUPPLY CONTROLLER 16TQFN |
| MAX1536ETI+ | IC REG BUCK SYNC ADJ 3.6A 28TQFN |
| MAX1538ETI+T | IC PWR SOURCE SELECTOR 28-TQFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1531EVKIT | 功能描述:电源管理IC开发工具 MAX1530/1 Eval Kit 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 |
| MAX1532AETL | 制造商:Maxim Integrated Products 功能描述:DUAL-PHASE, QUICK-PWM CONTROLLER FOR IMVP CPU - Rail/Tube |
| MAX1532AETL+ | 制造商:Maxim Integrated Products 功能描述:DUAL-PHASE, QUICK-PWM CONTROLLER FOR IMVP CPU - Rail/Tube |
| MAX1532AETL+T | 制造商:Maxim Integrated Products 功能描述:DUAL-PHASE, QUICK-PWM CONTROLLER FOR IMVP CPU - Tape and Reel 制造商:Maxim Integrated Products 功能描述:MULTIPLE OUTPUT POWER-SUPPLY CTRL |
| MAX1532AETL-T | 制造商:Maxim Integrated Products 功能描述:DUAL-PHASE, QUICK-PWM CONTROLLER FOR IMVP CPU - Tape and Reel |
发布紧急采购，3分钟左右您将得到回复。