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参数资料
| 型号： | MAX1778EUG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 31/39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
R 11 = R 12 ? ? SUPB ? - 1 ?
Input-to-Output (Dropout) Voltage and Startup
A linear regulator’s minimum input-to-output voltage dif-
ferential (dropout voltage) determines the lowest use-
able supply voltage. Because the MAX1778/
MAX1881/MAX1883/MAX1884 use an internal pnp tran-
sistor (or external npn transistor), their dropout voltage
is a function of the transistor’s collector-to-emitter satu-
ration voltage (see the Typical Operating
Characteristics). The linear regulator’s quiescent cur-
rent increases when in dropout.
The internal linear regulator tries to start up once its
supply voltage (V SUPL ) exceeds 4V. When the linear
regulator powers up, the linear regulator may be in
dropout if the linear regulator’s output set voltage is
higher than its input supply voltage. Therefore, during
this brief period, the linear regulator draws additional
supply current until the input supply voltage exceeds
the output set voltage plus the pass transistor’s satura-
tion voltage (V LDO(SET ) + V CE(SAT) ).
VCOM Buffer (Operational
Transconductance Amplifier)
Buffer Output Voltage and Capacitor Selection
The positive input (BUF+) features dual-mode opera-
tion. Connect BUF+ to GND for the preset V SUPB /2 out-
put voltage, set by an internal 50% resistive-divider.
Adjust the amplifier’s output voltage by connecting a
L1
voltage-divider from SUPB to BUF+ to GND (Figure 6).
Select R12 in the 10k ? to 100k ? range. Calculate R11
with the following equation:
? ?
? ? V ? ?
? ? V BUF + ? ?
where V SUPB can range from 4.5V to 13V, and V BUF+
can range from 1.2V to (V SUPB - 1.2V). Connect a mini-
mum 1μF ceramic capacitor from BUFOUT to ground.
PCB Layout and Grounding
Careful PCB layout is extremely important for proper
operation. Follow the following guidelines for good PCB
layout:
1) Place the main step-up converter output diode and
output capacitor less than 0.2in (5mm) from the LX
and PGND pins with wide traces and no vias.
2) Separate analog ground and power ground. The
ground connections for the step-up converter’s and
charge pump’s input and output capacitors should
be connected to the power ground plane. The lin-
ear regulator’s and VCOM buffer’s input and output
capacitors should be connected to a separate
power-ground path, star-connected to the PGND
pin to minimize voltage drops. When using multi-
INPUT
6.8 μ H
MAIN
V IN = 3.3V
C IN
4.7 μ F
C1
IN
SHDN
LX
FB
R1
274k ?
C OUT
(2) 4.7 μ F
V MAIN = 8V
0.22 μ F
R2
MAX1778
MAX1883
(MAX1881)*
(MAX1884)*
SUPL
49.9k ?
C LDOIN
1 μ F
C REF
0.22 μ F
INTG
REF
LDOOUT
R5
1.5k ?
C LDOOUT
4.7 μ F
C2
0.01 μ F
Q1
R3
49.9k ?
C LDO
1 μ F
LDO
V LDO = 2.5V
FBL
PGND
GND
C3
0.01 μ F
R4
49.9k ?
Figure 7. External Linear Regulator
Maxim Integrated
31
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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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