参数资料
| 型号： | MAX17498AATE+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 12/20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) |
MAX17498A/MAX17498B/MAX17498C
AC-DC and DC-DC Peak Current-Mode Converters
for Flyback/Boost Applications
= 0.75 ? C VCC IN SS × 0.1 +
+ I
× t
? μ F
C START
?
?
10
Startup Operation
The MAX17498A is optimized for implementing an offline
single-switch flyback converter and has a 20V IN UVLO
wake-up level with hysteresis of 15V (min). In offline appli-
cations, a simple cost-effective RC startup circuit is used.
When the input DC voltage is applied, the startup resis-
tor (R START ) charges the startup capacitor (C START ),
causing the voltage at the IN pin to increase towards the
wake-up IN UVLO threshold (20V typ). During this time,
the MAX17498A draws a low startup current of 20μA
(typ) through R START . When the voltage at IN reaches
the wake-up IN UVLO threshold, the MAX17498A com-
mences switching operations and drives the internal
n-channel MOSFET whose drain is connected to the LX
pin. In this condition, the MAX17498A draws 1.8mA cur-
rent from C START , in addition to the current required to
switch the gate of the external nMOSFET. Since this cur-
rent cannot be supported by the current through R START ,
the voltage on C START starts to drop. When suitably con-
figured, as shown in Figure 10 , the external nMOSFET is
switched by the LX pin and the flyback converter gener-
ates pulses in bias winding NB. The soft-start period of
the converter should be programmed so the bias winding
pulses sustain the voltage on C START before it falls below
5V, thus allowing continued operation. The large hystere-
sis (15V typ) of the MAX17498A allows for a small startup
capacitor (C START ). The low startup curent (20μA typ)
allows the use of a large start resistor (R START ), thus reduc-
ing power dissipation at higher DC bus voltages. Figure 3
shows the typical RC startup scheme for the MAX17498A.
R START might 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 so that
the voltage across each resistor is limited to the maximum
continuous operating-voltage rating. R START and C START
can be calculated as:
? 0.04 × t SS × Q G × f sw ?
6
where I IN is the supply current drawn at the IN
pin in mA, Q G is the gate charge of the external
nMOSFET in nC, f SW is the switching frequency of
the converter in Hz, and t SS is the soft-start time
programmed for the flyback converter in ms. C VCC is
the cummulative capacitor used in VCC node. See the
(SS) section.
R START
= ( V START ? 10 ) × 50 k ?
? ? 1 + C START ? ?
where C START is the startup capacitor in μF.
For designs that cannot accept power dissipation in the
startup resistors at high DC input voltages in offline appli-
cations, the startup circuit can be set up with a current
V DC
D2
V DC
D1
V OUT
R IN1
D2
V DC
D1
V OUT
V DC
R START
R IN2
NB
NP
NS
C OUT
NB
NP
NS
C OUT
R IN1
R IN3
IN
R START
R IN2
R IN3
C START
C VCC
IN
V CC
MAX17498A
LDO
LX
C START
R ISRC
C VCC
IN
V CC
MAX17498A
LDO
LX
Figure 3. MAX17498A RC-Based Startup Circuit
Maxim Integrated
Figure 4. MAX17498A Current Source-Based Startup Circuit
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17498BATE+ | 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 |
| MAX17498BATE+CER | 功能描述:直流/直流开关转换器 ACDC & DCDC Peak Crnt-Mode Cnvtrs RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX17498BATE+T | 功能描述:电流型 PWM 控制器 MAX17498BATE+T 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 |
| MAX17498BATE+TCER | 功能描述:直流/直流开关转换器 Universal ACDC & Iso DCDC Flyback cntlr RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX17498BEVKIT# | 功能描述:电源管理IC开发工具 MAX17498 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 |
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