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| 型号： | MAX1802EHJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 24/28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： | 2,500 |
| 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： | 带卷 (TR) |
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Digital Camera Step-Down
Power Supply
3) Place the compensation zero at the same frequency
as the maximum output pole frequency (in Hz):
80
180 °
Z C =
1
2 π R C C C
=
2V OUT ? V IN
2 π ( V OUT ? V IN ) R LOAD ( MIN ) C OUT
A VDC
60
P C
PHASE
? ? V ?
C C = C OUT OUT ?
?
V OUT IN
? ? R C OUT ( MAX ) ( 2V OUT IN ) ? ?
? V
Solving for CC:
V
I
GAIN
(dB)
40
20
Z C = P O
GAIN
90 °
PHASE
Use values of C C <10nF. If the above calculation deter-
O
0 °
mines that the capacitor should be >10nF, use C C =
10nF, skip step 4, and go to step 5.
-20
FREQUENCY
Z 0
4) Determine the crossover frequency (in Hz):
Figure 7. Discontinuous-Current, Voltage-Mode, Step-Up
f C =
V REF
π D C OUT
Controller Bode Plot
increasing the phase margin. If a low-value, low-ESR
and to maintain at least 10dB gain margin, make sure
that the crossover frequency is ≤ 1/3 of the ESR zero
frequency, or 3f C ≤ Z O , or ESR ≤ D / 6 V REF .
If this is not the case, go to step 5 to reduce the error-
amplifier high-frequency gain to decrease the
crossover frequency.
5) The high-frequency gain may be reduced, thus
reducing the crossover frequency, as long as the
zero due to the compensation network remains at or
output capacitor (such as a ceramic capacitor) is used,
the ESR-related zero occurs at too high a frequency
and does not increase the phase margin. In this case,
use a lower value inductor so that it operates with dis-
continuous current (see the Discontinuous Inductor
Current section).
For continuous inductor current, the gain of the voltage
divider is A VDV = V REF / V OUT, and the DC gain of the
error amplifier is A VEA = 2000. The gain through the
PWM controller in continuous current is:
ESR ≤
below the crossover frequency. In this case:
D
G EA R C 6 V REF
A VO =
V OUT 2
V IN V REF
Thus, the total DC loop gain is: A VDC = 2000 V OUT / V IN .
f C =
≥
P O =
P C =
=
and
G EA R C V REF 1
π D C OUT 2 π R C C C
Choose C OUT , R C , and C C to satisfy both equations
simultaneously.
Continuous Inductor Current
For continuous inductor current, there are two condi-
tions that change, requiring different compensation.
The response of the control loop includes a right-half-
The complex pole pair due to the inductor and output
capacitor occurs at the frequency (in Hz):
V OUT
2 π V IN LC OUT
The pole and zero due to the compensation network at
COMP occur at the frequencies (in Hz):
G EA 1
( 4000 π C C ) 4 × 10 7 π C C
plane zero and a complex pole pair due to the inductor
and output capacitor. For stable operation, the con-
troller-loop gain must drop below unity (0dB) at a much
lower frequency than the right-half-plane zero frequen-
cy. The zero arising from the ESR of the output capaci-
tor is typically used to compensate the control circuit
by increasing the phase near the crossover frequency,
Z C =
1
2 π R C C C
24
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| MAX1804EUB+T | 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 |
| MAX1804EUB-T | 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 |
| MAX1805EEE | 制造商:Maxim Integrated Products 功能描述: |
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