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参数资料
| 型号： | MAX1802EHJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 22/28页 |
| 文件大小： | 0K |
| 描述： | IC PWR SPLY STEP DOWN 32-TQFP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 360 |
| 应用： | 控制器，数字式相机 |
| 输入电压： | 2.5 V ~ 11 V |
| 输出数： | 5 |
| 输出电压： | 1.25 V ~ 5.5 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-TQFP |
| 供应商设备封装： | 32-TQFP（5x5） |
| 包装： | 托盘 |
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Digital Camera Step-Down
Power Supply
and the output voltage is I OUT R LOAD , which is equal to
I L R LOAD . Thus, the total DC loop gain is:
A VDC = R LOAD A VDV A VEA / (A VCSM R DSP )
180 °
or
A VDC = 215 V REF R LOAD / (V OUT R DS(ON) )
A VDC
P C
PHASE
Because of the current-mode control, there is a single
pole in the loop response due to the output capacitor.
This pole is at the frequency (in Hz):
GAIN
(dB)
Z C = P O
PHASE
MARGIN
90 °
PHASE
P O = 1 / (2 π R LOAD C OUT )
GAIN
Note that as the load resistance increases, the pole
moves to a lower frequency. However, the DC loop
gain increases by the same amount since they are both
dependent on R LOAD . Thus, the crossover frequency
(frequency at which the loop gain drops to 0dB), which
is the product of the pole and the gain, remains at the
same frequency.
O
FREQUENCY
Z 0
0 °
The compensation network creates a pole and zero at
the frequencies (in Hz):
P C = G EA / (4000 π C C ) = 1 / (4x107 π C C )
Figure 6. Current-Mode Step-Down Converter Bode Plot
or
and
Z C = 1 / (2 π R C C C )
P O =
I LOAD ( MAX )
2 π V OUT C OUT
and the ESR of the output filter capacitor causes a zero
in the loop response at the frequency (in Hz):
3) Determine the compensation resistor required to set
the desired crossover frequency:
Z O = 1 / (2 π C OUT ESR)
The DC gain and the poles and zeros are shown in the
R C =
20M ? f C
A VDC P O
Bode plot of Figure 6.
To achieve a stable circuit with the Bode plot of Figure
6, use the following procedure:
1) Determine the desired crossover frequency, either
1/3 of the zero due to the output capacitor ESR:
or, by simplifying and using the typical V REF = 1.25V:
R C = 468k ? /V V OUT C OUT R DSP f C
4) Determine the compensation capacitor to set the
proper error-amplifier pole and zero determined from
f C = Z O / 3 =
1
6 π C OUT E SR
or 1/5 of the switching frequency:
the above equations:
C C =
1
2 π R C P O
f C = SW
whichever is lower.
f
5
Core Converter
Compensating the core converter is similar to the com-
pensation of the main converter described above. The
only difference is that the current is measured internal-
2) Determine the pole frequency due to the output
capacitor and the load resistor:
ly, and the gain (transresistance) of the current-sense
amplifier is R CSC = 1.0V/A. The DC loop gain is:
P O =
1
2 π R LOAD ( MIN ) C OUT
A VDC = 2000 V REF R LOAD / V OUT
22
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相关代理商/技术参数 |
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| MAX1802EHJ+ | 功能描述:直流/直流开关转换器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1802EHJ+T | 功能描述:直流/直流开关转换器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1802EHJ-T | 功能描述:直流/直流开关转换器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1804EUB | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1804EUB+ | 功能描述:电流和电力监控器、调节器 Feedback Integrator for Power Supply RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
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