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| 型号： | MAX1778EUG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 20/39页 |
| 文件大小： | 0K |
| 描述： | IC DCDC CONV MULTI OUT 24TSSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 62 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 2.7 V ~ 5.5 V |
| 输出数： | 5 |
| 输出电压： | 2.7 V ~ 13 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-TSSOP（0.173"，4.40mm 宽） |
| 供应商设备封装： | 24-TSSOP |
| 包装： | 管件 |
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MAX1778/MAX1880–MAX1885
Quad-Output TFT LCD DC/DC
Converters with Buffer
Main Step-up Controller
During normal pulse-width modulation (PWM) opera-
tion, the MAX1778/MAX1880–MAX1885 main step-up
controllers switch at a constant frequency of 500kHz or
1MHz (see the Selector Guide), allowing the use of low-
profile inductors and output capacitors. Depending on
the input-to-output voltage ratio, the controller regulates
the output voltage and controls the power transfer by
modulating the duty cycle (D) of each switching cycle:
Changes in the feedback voltage-error signal shift the
switch-current trip level, consequently modulating the
MOSFET duty cycle.
Under very light loads, an inherent switchover to pulse-
skipping takes place (Figure 3). When this occurs, the
controller skips most of the oscillator pulses in order to
reduce the switching frequency and gate charge loss-
es. When pulse-skipping, the step-up controller initiates
a new switching cycle only when the output voltage
D ≈
V MAIN - V IN
V MAIN
drops too low. The n-channel MOSFET turns on, allow-
ing the inductor current to ramp up until the multi-input
comparator trips. Then, the MOSFET turns off and the
diode turns on, forcing the inductor current to ramp
On the rising edge of the internal clock, the controller
sets a flip-flop when the output voltage is too low, which
turns on the n-channel MOSFET (Figure 2). The induc-
tor current ramps up linearly, storing energy in a mag-
netic field. Once the sum of the feedback voltage error
amplifier, slope-compensation, and current-feedback
down. When the inductor current reaches zero, the
diode turns off, so the inductor stops conducting
current. This forces the threshold between pulse-skip-
ping and PWM operation to coincide with the boundary
between continuous and discontinuous inductor-
current operation:
?
?
? ?
signals trip the multi-input comparator, the MOSFET
turns off, the flip-flop resets, and the diode (D1) turns
on. This forces the current through the inductor to ramp
back down, transferring the energy stored in the mag-
I LOAD ( CROSSOVER ) ≈
1 ? V IN ?
2 ? ? V MAIN ? ?
2
? V MAIN - V IN ?
f OSC L
netic field to the output capacitor and load. The
MOSFET remains off for the rest of the clock cycle.
OSC
L1
V IN
(2.7V TO 5.5V)
MAX1778
MAX1880
MAX1881
(80% DUTY)
C IN
MAX1882
MAX1883
MAX1884
MAX1885
S
R
Q
LX
D1
C OUT
V MAIN
(UP TO 13V)
I LIM
PWM
COMPARATOR
ILIM
COMPARATOR
PGND
R1
R COMP
(OPTIONAL)
FB
g m
C COMP
(OPTIONAL)
ERROR
AMPLIFIER
INTG
V REF
1.25V
REF
GND
C REF
R2
R1
V MAIN = ( 1 + R2 ) V REF
V REF = 1.25V
C INTG
Figure 2. Main Step-Up Converter Block Diagram
20
Maxim Integrated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1778EUG+ | 功能描述:直流/直流开关转换器 Quad-Output TFT LCD w/Buffer 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 |
| MAX1778EUG+T | 功能描述:直流/直流开关转换器 Quad-Output TFT LCD w/Buffer 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 |
| MAX1778EUG-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 |
| MAX1778EVKIT | 功能描述:电源管理IC开发工具 MAX1778/80/81/82 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 |
| MAX1779EUE | 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 |
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