参数资料
型号: MAX1775EEE
厂商: Maxim Integrated Products
文件页数: 10/16页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM 16-QSOP
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 100
PWM 型: 控制器
输出数: 2
频率 - 最大: 1.25MHz
占空比: 100%
电源电压: 2.7 V ~ 28 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 85°C
封装/外壳: 16-SSOP(0.154",3.90mm 宽)
包装: 管件
Dual-Output Step-Down
DC-DC Converter for PDA/Palmtop Computers
IN
2.7V TO 5.5V
C1
6
8
1 μ F
ON
OFF
1
SHDNM
IN
CVH
INC
15
M1
C6
10 μ F
ON
OFF
2
SHDNC
PDRV
7
L M
5 μ H
R1
33m ?
MAIN
3.3V
2A
C2
5 CVL
NDRV
4
M2
R2
C4
47 μ F
1 μ F
MAX1775 CS+ 11
C5
C3
0.22 μ F
9
3
14
REF
PGND
GND
CS-
FBM
LXC
12
10
16
L C
5.4 μ H
R4
CORE
1.8V
22 μ F 1.5A
R3
FBC
13
R5
Figure 1. Typical Application Circuit (Low Input Voltage)
Detailed Description
The MAX1775 dual step-down DC-DC converter is
designed to power PDA, palmtop, and subnotebook
computers. Normally, these devices need two separate
power supplies—one for the processor and another
higher voltage supply for the peripheral circuitry. The
MAX1775 provides an adjustable +1.25V to +5.5V main
output designed to power the peripheral circuitry of
PDAs and similar devices. The main output delivers
over 2A output current. The lower voltage core convert-
er has an adjustable +1.0V to +5.0V output, providing
up to 1.5A output current. Both regulators utilize a pro-
prietary regulation scheme, allowing PWM operation at
medium to heavy loads, and automatically switch to
pulse skipping at light loads for improved efficiency.
Figure 1 is the typical application circuit.
Operating Modes for the
Step-Down Converters
When delivering low output currents, the MAX1775
operates in discontinuous conduction mode. Current
through the inductor starts at zero, rises above the min-
imum current limit, then ramps down to zero during
each cycle (see Typical Operating Characteristics).
The switch waveform may exhibit ringing, which occurs
at the resonant frequency of the inductor and stray
capacitance, due to the residual energy trapped in the
core when the rectifier MOSFET turns off. This does not
degrade the circuit performance.
When delivering medium-to-high output currents, the
MAX1775 operates in PWM continuous-conduction
mode. In this mode, current always flows through the
inductor and never ramps to zero. The control circuit
adjusts the switch duty cycle to maintain regulation
without exceeding the peak switching current set by
the current-sense resistor.
100% Duty Cycle and Dropout
The MAX1775 operates with a duty cycle up to 100%.
This feature extends the input voltage range by turning
the MOSFET on continuously when the supply voltage
approaches the output voltage. This services the load
when conventional switching regulators with less than
100% duty cycle would fail. Dropout voltage is defined
as the difference between the input and output volt-
ages when the input is low enough for the output to
drop out of regulation. Dropout depends on the MOS-
FET drain-to-source on-resistance, current-sense resis-
tor, and inductor series resistance, and is proportional
to the load current:
Dropout voltage =
I OUT   [R DS(ON) + R SENSE + R INDUCTOR ]
10
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MAX1775EEE+T 功能描述:直流/直流开关转换器 Dual-Out Step-Down for PDA/Palmtop 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
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MAX1775EEE-TG069 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1775EVKIT 功能描述:直流/直流开关转换器 Evaluation Kit for the MAX1775 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