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参数资料
| 型号： | MAX1878ETC+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/12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： | 是 |
| 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
Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12
—
NAME
IN
LX
AIN1
AIN2
FB
FBLCD
ON
AGND
LXLCD
ONLCD
PGNDLCD
PGND
EP
FUNCTION
Step-Down Converter Power Input. Connect IN to the step-down converter power source. Bypass IN to
PGND with a 10μF or greater low-ESR capacitor.
Step-Down Converter Switching Node. Connect LX to the step-down converter output LC filter. LX swings
between IN and PGND.
Analog Input Power 1. AIN1 supplies power to the MAX1878 internal circuitry. Connect AIN1 to the 2.0V to
5.5V input power source. Bypass AIN1 to AGND with a 1μF or greater low-ESR capacitor.
Analog Input Power 2. Connect AIN1 and AIN2 together as close to the MAX1878 as possible.
Step-Down Converter Feedback Input. Connect a resistive voltage-divider from the step-down converter
output voltage to FB. The regulation threshold is 1.25V at FB.
LCD Step-Up Converter Feedback Input. Connect a resistive voltage-divider from the step-up converter
output voltage to FBLCD. The regulation threshold is 1.25V at FBLCD.
Step-Down Converter On/Off Input. Drive ON high to turn on the step-down converter. Drive ON low to
turn off the converter. For automatic startup, connect ON to AIN1.
Analog (Low-Noise) Ground. The exposed pad and the corner tabs on the TQFN package are internally
connected to analog ground. See the PC Board Layout and Grounding section.
LCD Step-Up Converter Switching Node. Connect LXLCD to the step-up converter inductor and rectifier.
LCD Step-Up Converter On/Off Input. Drive ONLCD high to turn on the step-up converter. Drive ONLCD
low to turn off the converter. For automatic startup, connect ONLCD to AIN1.
LCD Step-Up Converter Power Ground. PGNDLCD is the source of the step-up converter’s internal
N-channel MOSFET switch. Connect PGNDLCD to PGND as close to the MAX1878 as possible.
Power Ground. PGND is the source of the step-down converter’s internal N-channel MOSFET
synchronous rectifier. Connect PGND to PGNDLCD as close to the MAX1878 as possible.
Exposed Pad. Internally connected to AGND. Connect to a large analog ground (AGND) plane to
maximize thermal performance. Not intended to use as an electrical connection point.
Detailed Description
The MAX1878 step-down and step-up DC-DC convert-
er operates from a 2.0V to 5.5V supply. Consuming
only 19μA of quiescent supply current, the main step-
down converter delivers over 500mA to an output as
low as 1.25V and the LCD step-up converter delivers
over 15mA and an output as high as 28V. The
MAX1878 uses a unique proprietary current-limited
control scheme that provides excellent performance
and high efficiency.
Step-Down Converter Control Scheme
The MAX1878 step-down converter uses a proprietary,
current-limited control scheme to ensure high efficiency,
fast transient response, and physically small external
components. This control scheme is simple: when the
output voltage is out of regulation, the error comparator
begins a switching cycle by turning on the high-side
switch. This switch remains on until the minimum on-
time of 440ns expires and the output voltage regulates
or the current-limit threshold is exceeded. Once off, the
high-side switch remains off until the minimum off-time
of 390ns expires and the output voltage falls out of regu-
lation. During this period, the low-side synchronous rec-
tifier turns on and remains on until either the high-side
switch turns on again or the inductor current approach-
es zero. The internal synchronous rectifier eliminates the
need for an external Schottky diode.
This control scheme allows the MAX1878 step-down
converter to provide excellent performance throughout
the entire load-current range. When delivering light
loads, the high-side switch turns off after the minimum
on-time and after the inductor current reaches the
135mA ideal mode threshold to reduce peak inductor
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相关代理商/技术参数 |
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| 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 |
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