参数资料
型号: MAX1878ETC+
厂商: Maxim Integrated Products
文件页数: 9/12页
文件大小: 0K
描述: IC REG BUCK BST SYNC ADJ 12TQFN
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 75
类型: 降压(降压),升压(升压)
输出类型: 可调式
输出数: 2
输出电压: 1.25 V ~ 28 V
输入电压: 2 V ~ 5.5 V
PWM 型: 电压模式
频率 - 开关: 500kHz
电流 - 输出: 500mA
同步整流器:
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 12-WQFN 裸露焊盘
包装: 管件
供应商设备封装: 12-TQFN-EP(4x4)
Dual-Output Step-Down and LCD Step-Up
Power Supply for PDAs
Design Procedure
FBLCD (Figure 1). Select an R4 from 30k Ω to 300k Ω .
Calculate R3 with the following equation:
R 3 = R 4 ?
? 1 ?
Setting the Output Voltage
Set the MAX1878 step-down converter output voltage
by connecting a resistive voltage-divider from V MAIN to
FB (Figure 1). Select an R2 from 30k Ω to 300k Ω .
? V LCD
? V FBLCD
?
?
Calculate R1 with the following equation:
where V FBLCD = 1.25V and V LCD may range from (V IN
R 1 =
R 2 xR 6 ( V MAIN ? V FB )
V FB ( R 6 + R 2 ) ? V MAIN xR 2
+ 1V) to 28V.
The FB and FBLCD input bias currents are a maximum
of 50nA. These small bias currents allow for large-value
where V FB = 1.25V, R6 = 2M Ω and V MAIN may range
from 1.25V to V IN .
Set the MAX1878 step-up converter output voltage by
connecting a resistive voltage-divider from V LCD to
V IN
feedback resistors that improve light-load efficiency. For
less than 1% output voltage error due to bias current,
feedback resistors should be chosen such that the cur-
rent through R2 is 100 times greater than I FB and the
current through R4 is 100 times greater than I FBLCD .
1
IN
3
AIN1
4
AIN2
MAX1878
LXLCD 9
V LCD
CURRENT
LIMIT
N
P
CURRENT
V MAIN
2 LX
CONTROL
LIMIT
LOGIC
N
TIMERS
5 FB
SOFT-
START
FBLCD 6
OFF
ON
7 ON
ONLCD 10
OFF
ON
Figure 2. Simplified Functional Diagram
PGND
12
AGND
8
PGNDLCD
11
_______________________________________________________________________________________
9
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相关代理商/技术参数
参数描述
MAX1878ETC+ 功能描述:直流/直流开关转换器 Dual-Output Step-Down 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
MAX1878ETC+T 功能描述:直流/直流开关转换器 Dual-Output Step-Down 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
MAX1878EVKIT 功能描述:直流/直流开关转换器 Evaluation Kit for the MAX1878 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
MAX1879EUA 功能描述:电池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel
MAX1879EUA+ 功能描述:电池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel