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| 型号： | MAX8742EAI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/34页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP 28-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 4.2 V ~ 30 V |
| 输出数： | 2 |
| 输出电压： | 3.3V，5V，2.5 V ~ 5.5 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 供应商设备封装： | 28-SSOP |
| 包装： | 带卷 (TR) |
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500kHz Multi-Output Power-Supply Controllers
with High Impedance in Shutdown
Table 3. SKIP PWM Table
SKIP
Low
Low
High
High
LOAD CURRENT
Light
Heavy
Light
Heavy
MODE
Idle
PWM
PWM
PWM
DESCRIPTION
Pulse skipping, supply current = 250μA at V IN =12V, discontinuous inductor
Constant-frequency PWM continuous-inductor current
Constant-frequency PWM continuous-inductor current
Constant-frequency PWM continuous-inductor current
V L
R1
R2
UNCOMPENSATED
TO PWM
LOGIC
FB_
HIGH-SPEED
LEVEL TRANSLATOR
AND BUFFER
OUTPUT DRIVER
I1
I2
I3
V BIAS
REF
CSH_
CSL_
SLOPE COMPENSATION
Figure 4. Main PWM Comparator Block Diagram
The output filter capacitors (Figure 1, C1 and C2) set a
dominant pole in the feedback loop that must roll off the
loop gain to unity before encountering the zero intro-
duced by the output capacitor’s parasitic resistance
(ESR) (see the Design Procedure section). A 50kHz
pole-zero cancellation filter provides additional rolloff
above the unity-gain crossover. This internal 50kHz
lowpass compensation filter cancels the zero due to fil-
ter-capacitor ESR. The 50kHz filter is included in the
loop in both fixed-output and adjustable-output modes.
Synchronous Rectifier Driver (DL)
Synchronous rectification reduces conduction losses in
the rectifier by shunting the normal Schottky catch
diode with a low-resistance MOSFET switch. Also, the
synchronous rectifier ensures proper startup of the
boost gate-driver circuit.
If the circuit is operating in continuous-conduction
mode, the DL drive waveform is the complement of the
DH high-side drive waveform (with controlled dead time
to prevent cross-conduction or “shoot-through”). In dis-
continuous (light-load) mode, the synchronous switch is
turned off as the inductor current falls through zero. The
synchronous rectifier works under all operating condi-
tions, including idle mode.
The SECFB signal further controls the synchronous switch
timing in order to improve multiple-output cross-regulation
(see the Secondary Feedback Regulation Loop section).
Internal V L and REF Supplies
An internal regulator produces the 5V supply (V L ) that
powers the PWM controller, logic, reference, and other
blocks within the IC. This 5V low-dropout linear regula-
tor supplies up to 25mA for external loads, with a
reserve of 25mA for supplying gate-drive power.
Bypass V L to GND with 4.7μF.
Important: Ensure that V L does not exceed 6V.
Measure V L with the main output fully loaded. If it is
pumped above 5.5V, either excessive boost-diode
capacitance or excessive ripple at V+ is the probable
cause. Use only small-signal diodes for the boost cir-
cuit (10mA to 100mA Schottky or 1N4148 are pre-
ferred), and bypass V+ to PGND with 4.7μF directly at
the package pins.
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8743EEI | 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 |
| MAX8743EEI+ | 功能描述:电流型 PWM 控制器 Dual Step-Down 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 |
| MAX8743EEI+T | 功能描述:电流型 PWM 控制器 Dual Step-Down 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 |
| MAX8743EEI-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 |
| MAX8743ETX | 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 |
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