MAX1677：紧凑的、高效率、双输出、升压型和LCD偏置DC-DC转换器

逻辑电路与LCD电源方案，仅消耗35µA的电源电流，外部元件数最少

The MAX1677 is a compact, high-efficiency, dual-output boost converter for portable devices needing two regulated supplies, typically for logic and liquid crystal displays (LCDs). Operation with inputs as low as 0.7V allows the MAX1677 to accept 1, 2, or 3-cell alkaline, NiCd, or NiMH batteries as well as 1-cell lithium-ion batteries. The device requires no external FETs and can maintain regulation while consuming only 20µA, making it ideal for hand-held pen-input and PDA devices operating with low-current "sleep" states. The MAX1677's primary regulator supplies up to 350mA at either a factory-preset 3.3V or an adjustable 2.5V to 5.5V output. On-chip synchronous rectification provides efficiencies up to 95%. 300kHz (or externally clocked) pulse-width-modulation (PWM) operation is particularly suitable for applications needing low noise, such as those with wireless features. The primary converter also features pin-selectable pulse-frequency-modulation (PFM) operation that consumes only 20µA. A 1µA shutdown state also minimizes battery drain. The MAX1677's secondary step-up converter supplies up to +28V or -28V for LCD bias, varactor tuning, or other high-voltage, low-current functions. Other MAX1677 features include precision reference, logic control inputs for both regulators, and an uncommitted comparator for low-battery detection or a reset function. The MAX1677 is supplied in Maxim's compact 16-pin QSOP package, which occupies no more space than a standard SO-8.

关键特性

No External FETs Required
Main Output
- Up to 350mA for Logic Supply
- Fixed 3.3V or Adjustable (2.5V to 5.5V)
- Synchronous Rectification for High Efficiency (up to 95%)
- 300kHz (200kHz to 400kHz Synchronizable)
- Fixed-Frequency PWM Operation
Secondary Output
- Up to +28V or -28V for LCD Bias
- Programmable Current Limit
0.7V to 5.5V Input Voltage Range
20µA Quiescent Current
1µA Shutdown Current
Low-Battery Comparator
Small 16-Pin QSOP Package

MAX1677：典型工作电路

应用

手持式终端
PDA
便携式仪表
便携电话

数据手册DataSheet

语言	下载文件	备注
英文	MAX1677.pdf	Rev 1; 12/2001

关键参数

Part Number	Primary Topology	Monitor/Control Features	DC-DC/Power Features	LCD/LED/Flash/CCD Features	V_IN (V)	V_IN (V)	V_OUT (V)	V_OUT (V)	Max. I_OUT (A)	Max. I_OUT (A)	Oper. Freq. (kHz)	Package/Pins	Budgetary Price
Part Number	Primary Topology	Monitor/Control Features	DC-DC/Power Features	LCD/LED/Flash/CCD Features	min	max	min	max	Max. I_OUT (A)	Max. I_OUT (A)	Oper. Freq. (kHz)	Package/Pins	See Notes
MAX1677	Step-Up	External Synch. Low Batt./POK Output Shutdown	Current Limit Fixed Freq./PWM Internal Switch Soft Start Sync. Rectifier	TFT Bias	0.7	5.5	2.5	5.5	0.35	0.35	400	QSOP/16	$3.26 @1k

开发工具

MAX1677EVKIT

技术资料

Regulated Dual Voltages Control STN-LCD Contrast

订购型号

型号	状况	推荐替代产品	封装	温度	RoHS/无铅
MAX1677EEE	停止供货	MAX1677EEE+	QSOP,；16引脚；30.9mm²	-40°C至+85°C	RoHS/无铅：否
MAX1677EEE+	生产中		QSOP,；16引脚；30.9mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX1677EEE+T	生产中		QSOP,；16引脚；30.9mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX1677EEE-T	停止供货	MAX1677EEE+T	QSOP,；16引脚；30.9mm²	-40°C至+85°C	RoHS/无铅：否

MAX1677.pdf MAX1677

Regulated Dual Voltages Control STN-LCD Contrast MAX1677

典型工作电路 MAX1677