参数资料
| 型号： | MAX17497AATE+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 15/30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
R DC1
V DC
V DC
V DC
D1
V OUTF
R SUM
R DC2
R DC3
R START
R IN1
R IN2
C OUTF
R EN
EN/UVLO
MAX17497A
MAX17497B
V OUTF
D2
R IN3
IN
MAX17497A
LDO
LXF
R OVI
OVI
C START
C VCC
V CC
? Q GATE sw ? ?
C START IN + ? ? ? × SSF μF
=
10
?
?
10
? ?
Figure 3. Programming EN/UVLO and OVI
Startup Operation
The MAX17497A is optimized for implementing offline
flyback converters. A cost-effective RC startup circuit
is used in offline applications. In this startup method,
when the input DC voltage is applied, the startup
resistor (R START ) charges the startup capacitor (C START ),
causing the voltage at the IN pin to increase towards the
rising IN UVLO threshold (20V typ). During this time, the
MAX17497A draws a low startup current of 20 F A (typ)
through R START . When the voltage at IN reaches the
rising IN UVLO threshold, the MAX17497A commences
switching operations and drives the internal nMOSFET
whose drain is connected to the LXF pin. In this con-
dition, the MAX17497A draws 2.5mA current in from
C START , in addition to the current required to switch the
gate of the external nMOSFET (Q1). Since this current
cannot be supported by the current through R START ,
the voltage on C START starts to drop. When suitably
configured as show in Figure 4 , the external nMOSFET
is switched by the LXF pin and the flyback converter
generates an output voltage (V OUTF ) bootstrapped to
the IN pin through the diode (D2). If V OUTF exceeds
the sum of 6V and the drop across D2 before the
voltage on C START falls below 5V, then the IN volt-
age is sustained by V OUTF , allowing the MAX17497A
to continue operating with energy from V OUTF . The
large hysteresis (15V typ) of the MAX17497A allows
for a small startup capacitor (C START ). The low startup
Maxim Integrated
Figure 4. MAX17497A RC-Based Startup Circuit
current (20 F A typ) allows the use of a large startup resis-
tor (R START ), thus reducing power dissipation at higher
DC bus voltages. R START may need to be implemented
as equal, multiple resistors in series (R IN1 , R IN2 and
R IN3 ) to share the applied high DC voltage in offline
applications, such that the voltage across each resistor
is limited to the maximum continuous operating-voltage
rating. R START and C START can be calculated as:
? × f t
6
where I IN is the supply current drawn at the IN pin in mA,
Q GATE is the gate charge of the external MOSFET used in
nC, f SW is the switching frequency of the converter in Hz,
and t SSF is the soft-start time programmed for the flyback
converter in ms (see the Programming the Soft-Start of the
R START
= ( V START ? 10 ) × 50 k ?
? ? 1 + C START ? ?
where C START is the startup capacitor in F F.
For designs that cannot accept power dissipation in
the startup resistors at high DC input voltages in offline
applications, the startup circuit can be set up with a
current source instead of a startup resistor, as shown
15
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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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