参数资料
| 型号： | MAX17497AATE+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 19/30页 |
| 文件大小： | 0K |
| 描述： | IC OFF-LINE CONVERTER 16TQFN |
| 产品培训模块： | Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 输出隔离： | 隔离 |
| 频率范围： | 235kHz ~ 265kHz |
| 输入电压： | 4.5 V ~ 29 V |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 供应商设备封装： | 16-TQFN-EP（3x3） |
| 包装： | 带卷 (TR) |
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MAX17497A/MAX17497B
AC-DC and DC-DC Peak Current-Mode Converters
with Integrated Step-Down Regulator
2.5 × L PRI × ( V OUTF + V D ) × I OUTF × f SW
D NEW =
( V OUTF + V D ) × (1 ? D NEW )
2 × L LK × I PRIPEAK 2 × K 2
V OUTF 2
I PRIPEAK = INMIN NEW
6.25 × V OUTF 2
P SNUB × K 2
= V 2.5 × OUTF
V DSNUB INMAX + ? ?
Duty-Cycle Calculation
The accurate value of the duty cycle (D NEW ) for the
selected primary inductance L PRI can be calculated
using the following equation:
V INMIN
Turns Ratio Calculation (Ns/Np)
Transformer turns ratio (K = Ns/Np) can be calculated as:
K =
V INMIN × D NEW
Peak/RMS Current Calculation
RMS current values in the primary and secondary are
needed by the transformer manufacturer to design the
wire diameter for the different windings. Peak current
calculations are useful in setting the current limit. Use the
following equations to calculate the primary and second-
ary peak and RMS currents:
Maximum primary peak current:
V × D
L PRI × f SW
Maximum primary RMS current:
parasitic inductances and capacitors in the circuit, such
as leakage inductance of the flyback transformer, cause
voltage overshoot and ringing. Snubber circuits are used
to limit the voltage overshoots to safe levels within the
voltage rating of the external nMOSFET. The snubber
capacitor can be calculated using the following equation:
C SNUB =
where L LK is the leakage inductance obtained from the
transformer specifications (usually 1% to 2% of the pri-
mary inductance).
The power dissipated in the snubber resistor is calcu-
lated using the following equation:
P SNUB = 0.833 × L LK × I PRIPEAK 2 × f SW
The snubber resistor can be calculated based on the
following equation:
R SNUB =
The voltage rating of the snubber diode is:
? V ?
? K ?
I PRIRMS
= I PRIPEAK ×
D NEW
3
Output-Capacitor Selection
X7R ceramic output capacitors are preferred in industrial
I SECPEAK = PRIPEAK
2 × I OUT × I PRIPEAK
I SECRMS =
C OUTF = STEP RESPONSE
t RESPONSE ? (
+
)
Maximum secondary RMS current:
I
K
Maximum secondary peak current:
3 × K
For current-limit setting, the peak current can be calcu-
lated as:
I LIMF
= I PRIPEAK × 1.2
Primary Snubber Selection
Ideally, the external nMOSFET experiences a drain-
source-voltage stress equal to the sum of the input volt-
age and the reflected voltage across the primary wind-
ing during the off period of the nMOSFET. In practice,
Maxim Integrated
applications due to their stability over temperature. The
output capacitor is usually sized to support a step load
of 50% of the maximum output current in the application
so that the output-voltage deviation is contained to 3% of
the output-voltage change. The output capacitance can
be calculated as:
I × t
? V OUTF
0.33 1
f C f SW
where I STEP is the load step, t RESPONSE is the response
time of the controller, D V OUTF is the allowable output volt-
age deviation, and f C is the target closed-loop crossover
frequency. f C is chosen to be 1/10 of the switching fre-
quency (f SW ). For the flyback converter, the output
capacitor supplies the load current when the main switch
19
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PDF描述 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17497AEVKIT# | 功能描述:电源管理IC开发工具 MAX17497 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 |
| MAX17497BATE+ | 功能描述:电流型 PWM 控制器 Univ AC/DC-Iso DC/DC Flyback controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17497BATE+T | 功能描述:电流型 PWM 控制器 Univ AC/DC-Iso DC/DC Flyback controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17498AATE+ | 功能描述:电流型 PWM 控制器 Uvrsl AC/DC & Iso DC/DC Flyback ctlr RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17498AATE+T | 功能描述:电流型 PWM 控制器 Uvrsl AC/DC & Iso DC/DC Flyback ctlr RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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