参数资料
型号: MAX5975AETE+
厂商: Maxim Integrated Products
文件页数: 14/20页
文件大小: 0K
描述: IC REG CTRLR FLYBK ISO CM 16TQFN
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: 84%
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 85°C
封装/外壳: 16-WFQFN 裸露焊盘
包装: 管件
Current-Mode PWM Controllers with Frequency
Dithering for EMI-Sensitive Power Supplies
8.7 × 10 9
R RT =
R CS =
Oscillator/Switching Frequency
The ICs’ switching frequency is programmable between
100kHz and 600kHz with a resistor R RT connected
between RT and GND. Use the following formula to
determine the appropriate value of R RT needed to gen-
erate the desired output-switching frequency (f SW ):
f SW
where f SW is the desired switching frequency.
Peak Current Limit
The current-sense resistor (R CS in the Typical
Application Circuits ), connected between the source
of the n-channel MOSFET and PGND, sets the current
limit. The current-limit comparator has a voltage trip level
(V CS-PEAK ) of 400mV. Use the following equation to cal-
culate the value of R CS :
400mV
I PRI
where I PRI is the peak current in the primary side of
the transformer, which also flows through the MOSFET.
When the voltage produced by this current (through the
current-sense resistor) exceeds the current-limit com-
parator threshold, the MOSFET driver (NDRV) terminates
the current on-cycle, within 35ns (typ).
V CSBL
(BLANKED CS
The devices implement 115ns of leading-edge blanking
to ignore leading-edge current spikes. These spikes
are caused by reflected secondary currents, current-
discharging capacitance at the FET’s drain, and gate-
charging current. Use a small RC network for additional
filtering of the leading-edge spike on the sense wave-
form when needed. Set the corner frequency between
10MHz and 20MHz.
After the leading-edge blanking time, the device moni-
tors V CS for any breaches of the peak current limit of
400mV. The duty cycle is terminated immediately when
V CS exceeds 400mV.
Output Short-Circuit Protection
with Hiccup Mode
When the device detects eight consecutive peak current-
limit events, the driver output is turned off for a restart
period, t RSTRT . After t RSTRT , the device undergoes
soft-start. The duration of the restart period depends
on the value of the capacitor at SS (C SS ). During this
period, C SS is discharged with a pulldown current of
I SS-DH (2 F A typ). Once its voltage reaches 0.15V, the
restart period ends and the device initiates a soft-start
sequence. An internal counter ensures that the minimum
restart period (t RSTRT-MIN ) is 1024 clock cycles when
the time required for C SS to discharge to 0.15V is less
than 1024 clock cycles. Figure 3 shows the behavior of
the device prior and during hiccup mode.
V CS-PEAK
(400mV)
VOLTAGE)
HICCUP
DISCHARGE WITH I SS_DS
V SS_H
SOFT-START
VOLTAGE,
V SS
t SS
t RSTRT
V SS_SD
Figure 3. Hiccup Mode Timing Diagram
14
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相关代理商/技术参数
参数描述
MAX5975AETE+ 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
MAX5975AETE+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
MAX5975BETE+ 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
MAX5975BETE+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
MAX5975CETE+ 制造商:Maxim Integrated Products 功能描述:CURRENT-MODE PWM CONTROLLERS WITH FREQUENCY DITHERING FOR EM - Rail/Tube