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参数资料
| 型号： | MAX5974EETE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 15/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR FLYBACK PWM 16-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 600kHz |
| 占空比： | 82% |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 是 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 包装： | 管件 |
MAX5974E/MAX5974F
Current-Mode PWM Controllers for
Low-Cost Flyback Supplies
Design the resistive divider by first selecting the value of
R EN1 to be on the order of 100kω. Then calculate R EN2
as follows:
where V S(MAX) is the maximum supply voltage. Obeying
this relationship eliminates the need for an external zener
diode.
EN2
V = R EN1 ×
V EN(MAX)
V S(UVLO) ? V EN(MAX)
The digital output connected to EN should be capable of
withstanding more than 20V.
Always-On Operation
where V EN(MAX) is the maximum enable threshold volt-
age and is equal to 1.26V and V S(UVLO) is the desired
UVLO threshold for the power source, below which the
device is disabled.
The digital output connected to EN should be capable
of withstanding more than the maximum supply voltage.
MCU Control of Enable Input
When using a microcontroller GPIO to control the enable
input, an 18V zener diode is required on IN as shown in
Figure 2.
High-Voltage Logic Control of Enable Input
In the case where EN is externally controlled by a high-
voltage open-drain/collector output (e.g., PGOOD indi-
cator of a powered device controller), connect IN to EN
through a resistor REN and connect EN to an open-drain
or open-collector output as shown in Figure 3. Select
REN so that the voltage at IN, when EN is low, is less
than 20V (i.e., the maximum gate voltage of the main
For always-on operation, connect EN to IN as shown
in Figure 4. No external zener diode is needed for this
configuration.
Bootstrap Undervoltage Lockout
The devices have an internal bootstrap UVLO that is very
useful when designing high-voltage power supplies (see
the Block Diagram ). This allows the device to bootstrap
itself during initial power-up. The MAX5974E soft-starts
when V IN exceeds the bootstrap UVLO threshold of
V INUVR (16V typ).
Because the MAX5974F is designed for use with low-
voltage power sources such as wall adapters outputting
12V to 24V, they have a lower UVLO wake-up threshold
of 8.4V.
Startup Operation
The devices start up when the voltage at IN exceeds 16V
(MAX5974E) or 8.4V (MAX5974F) and the enable input
voltage is greater than 1.26V.
and AUX FETs):
V S(MAX) ×
R EN
R EN + R IN
< 20V
During normal operation, the voltage at IN is normally
derived from a tertiary winding of the transformer.
However, at startup there is no energy being delivered
V S
R IN
R IN
V S
R EN1
IN
IN
HIGH-VOLTAGE
DIGITAL LOGIC
18V
C IN
EN
MAX5974E
MAX5974F
18V
MCU
C IN
MAX5974E
MAX5974F
N
R EN2
I/O
EN
Figure 1. Programmable UVLO for the Power Source
Maxim Integrated
Figure 2. MCU Control of the Enable Input
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX5974EETE+ | 功能描述:电流型 PWM 控制器 Current-Mode PWM 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 |
| MAX5974EETE+T | 功能描述:电流型 PWM 控制器 Current-Mode PWM 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 |
| MAX5974EEVKIT# | 功能描述:电流型 PWM 控制器 MAX5974E Eval Kit 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 |
| MAX5974FETE+ | 功能描述:电流型 PWM 控制器 Current-Mode PWM 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 |
| MAX5974FETE+T | 功能描述:电流型 PWM 控制器 Current-Mode PWM 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 |
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