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参数资料
| 型号： | MAX1800 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | Digital Camera Step-Up Power Supply |
| 中文描述： | 数码相机升压型电源 |
| 文件页数： | 17/24页 |
| 文件大小： | 461K |
| 代理商： | MAX1800 |
M
Digital Camera Step-Up
Power Supply
______________________________________________________________________________________
17
Auxiliary Controllers
The auxiliary controllers use voltage mode to regulate
their output voltages, so the control-loop compensation
is slightly more complex than that for the main convert-
er. Use one of the two following procedures:
Discontinuous Inductor Current
For discontinuous inductor current, the PWM converter
has a single pole. The pole frequency and DC gain of
the PWM controller are dependent on the operating
duty cycle, which is:
where R
E
is the equivalent load resistance, or:
The frequency of the single pole due to the PWM con-
verter is:
(
(
The DC gain of the PWM controller is:
Note that the pole frequency decreases and the DC
gain increases proportionally as the load resistance
(R
LOAD
) is increased. Since the crossover frequency is
the product of the pole frequency and the DC gain, it
remains independent of the load.
The gain through the voltage-divider is:
The DC gain of the error amplifier is A
VEA
= 2000V/V.
Thus, the DC loop gain is:
A
VDC
= A
VDV
A
VEA
A
VO
The compensation resistor-capacitor pair at COMP
cause a pole and zero at frequencies (in Hz):
The equivalent series resistance (ESR) of the output fil-
ter capacitor causes a zero in the loop response at the
frequency (in Hz):
The DC gain, and the poles and zeros are shown in the
Bode plot of Figure 6.
To achieve a stable circuit with the Bode plot of Figure
6, perform the following procedure:
1) Choose the compensation resistor R
C
that is equiv-
alent to the inverse of the transconductance of the
error amplifier, 1/ R
C
= G
EA
= 100μS, or R
C
= 10k
.
This sets the high-frequency voltage gain of the
error amplifier to 0dB.
2) Determine the maximum output pole frequency:
where:
R
LOAD(MIN)
OUT
V
OUT(MAX)
I
=
P
2(V
- V
V
- V
C
O(MAX)
OUT
) R
IN)
OUT
IN
LOAD(MIN)
OUT
=
2
π
(
Z
C
ESR
O
OUT
=
1
2
π
P
G
C
C
Z
R C
C
EA
π
C
C
C
C
=
=
=
4000
1
7
4 10
1
2
π
π
A
V
V
VDV
REF
OUT
=
A
V
V
V
V
V
R
C
VO
OUT
OUT
IN
IN
OUT
LOAD
OUT
=
(
)
2
2
(
)
π
P
V
V
V
V
R
C
O
OUT
IN
OUT
IN
LOAD
OUT
=
)
)
2
2
π
R
V
R
V
V
V
E
IN
LOAD
OUT
OUT
IN
=
(
)
2
D
Lf
R
OSC
E
=
2
1
2
FREQUENCY
A
VDC
GAIN
(dB)
PHASE
180
°
90
°
0
°
O
-20
80
60
40
20
PHASE
GAIN
Z
C
= P
O
P
C
Z
O
Figure 6. MAX1800 Discontinuous-Current, Voltage-Mode,
Step-Up Converter Bode Plot
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1800EHJ | 功能描述:直流/直流开关转换器 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 |
| MAX1800EHJ-T | 功能描述:直流/直流开关转换器 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 |
| MAX1800EVKIT | 功能描述:电源管理IC开发工具 RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX1801EKA | 制造商:Maxim Integrated Products 功能描述:DIGITAL CAMERA STEP-UP SLAVE DC-DC - Rail/Tube |
| MAX1801EKA+ | 制造商:Maxim Integrated Products 功能描述:DC DC CNTRLR SGL-OUT STEP UP 2.7V TO 5.5V 8PIN SOT-23 - Rail/Tube |
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