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参数资料
| 型号： | MAX5975AETE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/20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： | 无 |
| 升压： | 无 |
| 回扫： | 是 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 是 |
| 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
m = CSSC SW
f TRI =
V OUT REF × FB1 FB2
= V
4 R RT
where V MIN is described in the Duty-Cycle Clamping
section, f SW is the switching frequency as set by the
resistor connected between RT and GND, and f SYNC is
the external clock frequency.
Frequency Dithering for
Spread-Spectrum Applications (Low EMI)
The switching frequency of the converter can be dith-
ered in a range of Q 10% by connecting a capacitor from
SYNC/DITHER to GND, and a resistor from DITHER to
RT as shown in the Typical Applications Circuits . This
results in lower EMI.
A current source at SYNC/DITHER charges the capaci-
tor C DITHER to 2V at 50 F A. Upon reaching this trip point,
it discharges C DITHER to 0.4V at 50 F A. The charging
and discharging of the capacitor generates a triangular
waveform on SYNC/DITHER with peak levels at 0.4V and
2V and a frequency that is equal to:
50 μ A
C DITHER × 3.2V
Typically, f TRI should be set close to 1kHz. The resistor
R DITHER connected from SYNC/DITHER to RT deter-
mines the amount of dither as follows:
%DITHER = ×
3 R DITHER
where %DITHER is the amount of dither expressed as a
percentage of the switching frequency. Setting R DITHER
to 10 x R RT generates Q 10% dither.
Programmable Slope Compensation
The devices generate a current ramp at CSSC such
that its peak is 50 F A at 80% duty cycle of the oscillator.
An external resistor connected from CSSC to CS then
converts this current ramp into programmable slope-
compensation amplitude, which is added to the current-
16
sense signal for stability of the peak current-mode
control loop. The ramp rate of the slope compensation
signal is given by:
R × 50 μ A × f
80%
where m is the ramp rate of the slope-compensation
signal, R CSSC is the value of the resistor connected
between CSSC and CS used to program the ramp rate,
and f SW is the switching frequency.
Error Amplifier
The MAX5975A/MAX5975B include an internal error
amplifier. The noninverting input of the error ampli-
fier is connected to the internal 1.215V reference and
feedback is provided at the inverting input. High 80dB
open-loop gain and 30MHz unity-gain bandwidth allow
good closed-loop bandwidth and transient response.
Calculate the power-supply output voltage using the fol-
lowing equation:
R + R
R FB2
where V REF = 1.215V.
Applications Information
Startup Time Considerations
The bypass capacitor at IN, C IN , supplies current
immediately after the devices wake up (see the Typical
Application Circuits ). Large values of C IN increase
the startup time, but also supply gate charge for more
cycles during initial startup. If the value of C IN is too
small, V IN drops below 7V because NDRV does not have
enough time to switch and build up sufficient voltage
across the tertiary output, which powers the device. The
device goes back into UVLO and does not start. Use a
low-leakage capacitor for C IN .
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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 |
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