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参数资料
| 型号： | MAX8643ETG+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 13/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3A 24TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 3.2 V |
| 输入电压： | 2.35 V ~ 3.6 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 500kHz ~ 2MHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 24-TQFN-EP（4x4） |
3A, 2MHz Step-Down Regulator
with Integrated Switches
The zero-cross frequency of the closed-loop, f C , should
COMPENSATION
TRANSFER
FUNCTION
DOUBLE POLE
OPEN-LOOP
GAIN
THIRD
POLE
be between 10% and 20% of the switching frequency,
f S . A higher zero-cross frequency results in faster tran-
sient response. Once f C is chosen, C1 is calculated
from the following equation:
2 x π x R 3 x ( 1 + L ) × f C
GAIN (dB)
POWER-STAGE
TRANSFER
SECOND
POLE
C 1 =
1 . 5625 V IN
R
R O
FUNCTION
FIRST AND SECOND ZEROS
Figure 4. Type III Compensation Illustration
Due to the underdamped nature of the output LC dou-
ble pole, set the two zero frequencies of the type III
compensation less than the LC double-pole frequency
to provide adequate phase boost. Set the two zero fre-
quencies to 80% of the LC double-pole frequency.
Hence:
f Z 2 _ EA =
1
2 π x R 3 x C 3
R 1 =
1
0 . 8 x C 1
x
L x C O x ( R O + ESR )
R L + R O
f P 3 _ EA =
f P 2 _ EA =
1 L x C O x ( R O + ESR )
1
2 π x R 1 x C 2
1
2 π x R 2 x C 3
C 3 = x
0 . 8 x R 3 R L + R O
Setting the second compensation pole, f P2_EA , at
f Z_ESR yields:
The above equations are based on the assumptions
that C1>>C2, and R3>>R2, which are true in most
applications. Placements of these poles and zeros are
R 2 =
C O x ESR
C 3
C 2 =
determined by the frequencies of the double pole and
ESR zero of the power transfer function. It is also a
function of the desired closed-loop bandwidth. The fol-
lowing section outlines the step-by-step design proce-
dure to calculate the required compensation
components for the MAX8643. When the output voltage
of the MAX8643 is programmed to a preset voltage, R3
is internal to the IC and R4 does not exist (Figure 3b).
When externally programming the MAX8643 (Figure
3a), the output voltage is determined by:
Set the third compensation pole at 1/2 of the switching
frequency to gain some phase margin. Calculate C2 as
follows:
1
π x R 1 x f S × 2
The above equations provide accurate compensation
when the zero-cross frequency is significantly higher
than the double-pole frequency. When the zero-cross
frequency is near the double-pole frequency, the actual
R 4 =
0 . 6 × R 3
( V OUT ? 0 . 6 )
zero-cross frequency is higher than the calculated fre-
quency. In this case, lowering the value of R1 reduces
the zero-cross frequency. Also, set the third pole of the
type III compensation close to the switching frequency
if the zero-cross frequency is above 200kHz to boost
the phase margin. The recommended range for R3 is
2k ? to 10k ? . Note that the loop compensation remains
unchanged if only R4’s resistance is altered to set dif-
ferent outputs.
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8643EVKIT+ | 功能描述:电源管理IC开发工具 MAX8643 Eval Kit 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 |
| MAX8645XETI | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8645XETI+ | 功能描述:LED照明驱动器 1x/1.5x/2x White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX8645XETI+T | 功能描述:LED照明驱动器 1x/1.5x/2x White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX8645YETI+ | 功能描述:LED照明驱动器 1x/1.5x/2x White LED Charge Pump RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
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