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参数资料
| 型号： | MAX1847EEE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR FLYBK INV CM 16QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 345kHz |
| 占空比： | 98% |
| 电源电压： | 3 V ~ 16.5 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 是 |
| 反相： | 是 |
| 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-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1410 (CN2011-ZH PDF) |
High-Efficiency, Current-Mode,
Inverting PWM Controller
Select the next smaller standard value of resistor and
then calculate the compensation capacitor required to
cancel out the output-capacitor-induced pole (P OUT1 )
determined previously.
Applications Information
Maximum Output Power
The maximum output power that the MAX1846/MAX1847
can provide depends on the maximum input power
C COMP =
1
6 . 28 x P OUT 1 x R COMP
available and the circuit’s efficiency:
P OUT(MAX) = Efficiency P IN(MAX)
Furthermore, the efficiency and input power are both
Choose the next larger standard value of capacitor.
In order for p COMP to compensate the loop, the open-
loop gain must reach unity at a lower frequency than
the right-half-plane zero or the second output pole,
whichever is lower in frequency. If the second output
pole and the right-half-plane zero are close together in
frequency, the higher resulting phase shift at unity gain
may require a lower crossover frequency. For duty
cycles greater than 50%, slope compensation reduces
A DC , reducing the actual crossover frequency from
f CROS . It is also a good practice to reduce noise on
COMP with a capacitor (C COMP2 ) to ground. To avoid
adding extra phase margin at the crossover, the
capacitor (C COMP2 ) should roll-off noise at five times
the crossover frequency. The value for C COMP2 can be
found using:
functions of component selection. Efficiency losses can
be divided into three categories: 1) resistive losses
across the inductor, MOSFET on-resistance, current-
sense resistor, rectification diode, and the ESR of the
input and output capacitors; 2) switching losses due to
the MOSFET’s transition region, and charging the MOS-
FET’s gate capacitance; and 3) inductor core losses.
Typically, 80% efficiency can be assumed for initial cal-
culations. The required input power depends on the
inductor current limit, input voltage, output voltage, out-
put current, inductor value, and the switching frequen-
cy. The maximum output power is approximated by the
following formula:
P MAX = [V IN - (V LIM + I LIM x R DS(ON) )] x I LIM x
[1 - (LIR / 2)] x [(-V OUT + V D ) / (V IN - V SW - V LIM
- V OUT + V D )]
C COMP 2 =
R O + R COMP
5 x 6 . 28 x f CROS x R O x R COMP
where I LIM is the peak current limit and LIR is the
inductor current-ripple ratio and is calculated by:
LIR = I LPP / I LDC
It might require a couple iterations to obtain a suitable
combination of compensation components.
Finally, the zero introduced by the output capacitor’s
ESR must be compensated. This compensation is
accomplished by placing a capacitor between REF
and FB creating a pole directly in the feedback loop.
Calculate the value of this capacitor using the frequen-
cy of z ESR and the selected feedback resistor values
with the formula:
Again, remember that V OUT for the MAX1846/
MAX1847 is negative.
Diode Selection
The MAX1846/MAX1847 ’s high-switching frequency
demands a high-speed rectifier. Schottky diodes are
recommended for most applications because of their fast
recovery time and low forward voltage. Ensure that the
diode’s average current rating exceeds the peak inductor
current by using the diode manufacturer ’s data.
Additionally, the diode’s reverse breakdown voltage must
C FB = R ESR x C OUT x
R 1 + R 2
R 1 xR 2
exceed the potential difference between V OUT and the
input voltage plus the leakage-inductance spikes. For
high output voltages (-50V or more), Schottky diodes may
When using low-ESR, ceramic chip capacitors (MLCCs)
at the output, calculate the value of C FB as follows:
not be practical because of this voltage requirement. In
these cases, use an ultrafast recovery diode with ade-
quate reverse-breakdown voltage.
C FB =
R 1 + R 2
2 × 3 . 14 × f OSC × R 1 × R 2
Input Filter Capacitor
The input capacitor (C IN ) must provide the peak current
into the inverter. This capacitor is selected the same way
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1847EEE+ | 功能描述:电流型 PWM 控制器 Current-Mode Invert 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 |
| MAX1847EEE+ | 制造商:Maxim Integrated Products 功能描述:PWM CONTROLLER ((NW)) |
| MAX1847EEE+T | 功能描述:电流型 PWM 控制器 Current-Mode Invert 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 |
| MAX1847EEE-T | 功能描述:电流型 PWM 控制器 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 |
| MAX1848EKA | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY UNIFORM-BRIGHTNESS - Rail/Tube |
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