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参数资料
| 型号： | MAX5974EETE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/22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
V S
R IN
V S
C IN
R EN
IN
MAX5974E
MAX5974F
R IN
HIGH-VOLTAGE
DIGITAL LOGIC
EN
C IN
IN
MAX5974E
MAX5974F
N
Figure 3. High-Voltage Logic Control of the Enable Input
through the transformer; hence, a special bootstrap
sequence is required. In the Typical Application Circuit ,
C IN charges through the startup resistor, R IN , to an
intermediate voltage. Only 100 F A of the current supplied
through R IN is used by the ICs, the remaining input cur-
rent charges C IN until V IN reaches the bootstrap UVLO
wake-up level. Once V IN exceeds this level, NDRV
begins switching the n-channel MOSFET and transfers
energy to the secondary and tertiary outputs. If the volt-
age on the tertiary output builds to higher than 7V (the
bootstrap UVLO shutdown level), then startup has been
accomplished and sustained operation commences.
If V IN drops below 7V before startup is complete, the
device goes back to low-current UVLO. In this case,
increase the value of C IN to store enough energy to allow
for the voltage at the tertiary winding to build up.
Soft-Start
A capacitor from SS to GND, C SS , programs the soft-
start time. V SS controls the oscillator duty cycle during
startup to provide a slow and smooth increase of the
duty cycle to its steady-state value. Calculate the value
of C SS as follows:
EN
Figure 4. Always-On Operation
A resistor can also be added from the SS pin to GND to
clamp V SS < 2V and, hence, program the maximum duty
cycle to be less than 80% (see the Duty-Cycle Clamping
section).
NDRV Driver
The NDRV output drives an external n-channel MOSFET.
NDRV can source/sink in excess of 650mA/1000mA
peak current; therefore, select a MOSFET that yields
acceptable conduction and switching losses. The exter-
nal MOSFET used must be able to withstand the maxi-
mum clamp voltage.
AUXDRV Driver
The AUXDRV output drives the output synchronous recti-
fier to lower conduction losses.
Dead Time
Dead time between the main and AUX output edges
allow ZVS to occur, minimizing conduction losses and
improving efficiency. The dead time (t DT ) is applied to
both leading and trailing edges of the main and AUX out-
puts as shown in Figure 5. Connect a resistor between
DT and GND to set t DT to any value between 40ns and
400ns:
C SS = SS-CH SS
I × t
2V
where I SS-CH (10 F A typ) is the current charging C SS dur-
ing soft-start and t SS is the programmed soft-start time.
16
R DT
=
10k ?
40ns
× t DT
Maxim Integrated
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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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