- 您现在的位置：买卖IC网 > Sheet目录341 > MAX8513EVKIT (Maxim Integrated Products)EVAL KIT FOR MAX8513
Wide-Input, High-Frequency, Triple-Output Supplies
with Voltage Monitor and Power-On Reset
diode on the secondary side (Q2 and D2 in the Typical
Applications Circuits ). n 2 and n 1 are the number of
turns of the secondary winding and the primary wind-
dropping out of regulation. The value of the storage
capacitor, C S , can be calculated as:
C S = ? 0 . 5 × ? × ?
t WARN
( V PFI - V DROOP )
ing, respectively.
It is important to have the secondary winding tightly
coupled with the primary winding to minimize leakage
inductance for higher efficiency. The positive voltage
generated by the secondary winding can also be
×
? P OUT 1 ? ? 1
? η ? ? V PFI
-
1 ?
V DROOP ? ?
stacked with the main DC-DC step-down converter out-
put to further improve efficiency and reduce winding
cost. In this case, the secondary-side voltage is:
where P OUT1 is the total output power, η is the total
converter efficiency, V PFI is the input voltage value at
the input power-fail (PFI) trip threshold, and V DROOP is
) × ? ? nn 2 ? ?
V SEC = ( V OUT 1 + V Q 2
? ?
1
+ V OUT 1 - V D2
the input voltage value where V OUT1 starts dropping
out of regulation.
V PFI and V DROOP can be calculated as:
V PFI = 1 . 22 V × ? 1 +
R 11 ?
Input Capacitor
The input-filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
?
?
R 10 ?
?
ripple on the input caused by the AC-RMS current
through the ESR of the input capacitor (C2 in the Typical
Applications Circuits ). The input capacitor must meet
where R10 and R11 are the resistive-dividers from IN to
PFI to GND in the Typical Applications Circuits .
the ripple-current requirement (I IN_RMS ) imposed by the
switching currents defined by the following equation:
V DROOP =
V OUT1
D MAX
V OUT 1 × ( V IN OUT 1 )
I IN _ RMS =
I OUT 1 ×
V IN
- V
where D MAX is the maximum duty cycle.
To ensure for worst-case component tolerances such
I IN_RMS has a maximum value when the input voltage
equals twice the output voltage (V IN = 2 × V OUT1 ), so
I IN_RMS(MAX) = I OUT1 / 2. Ceramic capacitors are rec-
ommended due to their low ESR and ESL at high fre-
quency, with relatively low cost. Choose a capacitor that
exhibits less than 10 ° C temperature rise at the maximum
operating RMS current for optimum long-term reliability.
For applications that require input power-fail warning,
such as dying gasp, add a large-value electrolytic
capacitor (C S ) to the input as a local energy storage
device to provide the power to the converter in case of
input power-fail. The capacitor value must be high
enough to meet the desired power-fail warning time,
t WARN , where t WARN is the time from when PFI trips the
PFO output to when the main output (OUT1) starts
as capacitance of C S , converter efficiency, V PFI , and
V DROOP ’s threshold over the operating temperature
range, it is recommended to select C S at least 1.5 times
the calculated value above.
Output Capacitor
The key selection parameters for the output capacitor
are the actual capacitance value, the equivalent series
resistance (ESR), the equivalent series inductance
(ESL), and the voltage-rating requirements. All of these
affect the overall stability, output ripple voltage, and
transient response.
The output ripple is composed of three components: vari-
ations in the charge stored in the output capacitor, the
voltage drop across the capacitor’s equivalent series
resistance (ESR), and equivalent series inductance (ESL)
caused by the current into and out of the capacitor.
______________________________________________________________________________________
19
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
MAX8552EUB+
IC DRIVER MOSFET HS 10-UMAX
MAX8595XETA+T
IC LED DRIVR WHITE BCKLGT 8-TDFN
MAX8607ETD+T
IC LED DRIVR PHOTO FLASH 14-TDFN
MAX8608YETD+T
IC LED DRVR WT/OLED BCKLT 14TDFN
MAX8631XETI+T
IC LED DRVR WHITE BCKLGT 28-TQFN
MAX8645YETI+T
IC LED DRVR WHITE BCKLGT 28-TQFN
MAX8647ETE+T
IC LED DRVR WT/RGB BCKLGT 16TQFN
MAX8702ETP+
IC DRVR MOSFET DUAL 20-TQFN
相关代理商/技术参数
MAX8514AEI
功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK
MAX8514AEI-T
功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK
MAX8514EEI
功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK
MAX8514EEI-T
功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK
MAX8515AEXK
制造商:Maxim Integrated Products 功能描述:WIDE-INPUT 0.6V SHUNT REGULATOR FOR - Rail/Tube 制造商:Rochester Electronics LLC 功能描述:
MAX8515AEXK+
制造商:Maxim Integrated Products 功能描述:V-REF ADJUSTABLE 0.2V TO 18V 20MA 5PIN SC-70 - Rail/Tube
MAX8515AEXK+T
功能描述:基准电压& 基准电流 Shunt Regulator RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel
MAX8515AEXK-T
功能描述:基准电压& 基准电流 RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel