MAX849：1节至3节电池、大功率、低噪声、升压型DC-DC转换器

集成2路ADC，提供精确的电池电压监测

The MAX848/MAX849 boost converters set a new standard of high efficiency and high integration for noise-sensitive power-supply applications, such as portable phones and small systems with RF data links. The heart of the these devices is a synchronous boost-topology regulator that generates a fixed 3.3V output (or 2.7V to 5.5V adjustable output) from one to three NiCd/NiMH cells or one Li-Ion cell. Synchronous rectification provides a 5% efficiency improvement over similar nonsynchronous boost regulators. In standby mode, pulse-skipping PFM operation keeps the output voltage alive with only 150µW quiescent power consumption. Fixed-frequency PWM operation ensures that the switching noise spectrum is limited to the 300kHz fundamental and its harmonics, allowing easy post-filtering noise reduction. For even tighter noise spectrum control, synchronize to a 200kHz to 400kHz external clock. Battery monitoring is provided by a two-channel, voltage-to-frequency analog-to-digital converter (ADC). One channel is intended for a single-cell battery input (0.625V to 1.875V range), while the other channel is for monitoring higher voltages (0V to 2.5V range). Two control inputs are provided for push-on, push-off control via a momentary pushbutton switch. Upon power-up, an internal comparator monitors the output voltage to generate a power-good output (POK). The devices differ only in the current limit of the N-channel MOSFET power switch: 0.8A for the MAX848, and 1.4A for the MAX849.

关键特性

Up to 95% Efficiency
3.3V Dual Mode™ or 2.7V to 5.5V Adj. Output
0.7V to 5.5V Input Range
0.15mW Standby Mode
300kHz PWM Mode or Synchronizable
Two-Channel ADC with Serial Output
Power-Good Function

MAX848、MAX849：典型工作电路

应用

蜂窝电话
数字无绳电话
手持式仪表(PDA、掌上电脑)
本地3.3V至5V转换电源
掌上电脑
PCS电话
个人通信装置

数据手册DataSheet

语言	下载文件	备注
英文	MAX848-MAX849.pdf	Rev 2; 12/1997

关键参数

Part Number	V_IN (V)	V_IN (V)	V_OUT1 (V)	V_OUT1 (V)	Preset V_OUT (V)	I_OUT1 (A)	Output Adjust. Method	Switch Type	Synchronous Switching	I_CC (mA)	Shutdown Mode Supply Current (µA)	Shutdown Mode Supply Current (µA)	DC-DC Outputs	Oper. Freq. (kHz)	Package/Pins	Budgetary Price
Part Number	min	max	min	max	Preset V_OUT (V)	max	Output Adjust. Method	Switch Type	Synchronous Switching	typ	typ	max	DC-DC Outputs	Oper. Freq. (kHz)	Package/Pins	See Notes
MAX848	0.7	5.5	2.7	5.5	3.3	0.3	Preset Resistor	Internal	Yes	0.035	4	20	1	400	SOIC(N)/16	$2.38 @1k
MAX849	0.7	5.5	2.7	5.5	3.3	1	Preset Resistor	Internal	Yes	0.035	4	20	1	400	SOIC(N)/16	$2.50 @1k

开发工具

MAX849EVKIT

技术资料

Linear Regulators in Portable Applications

订购型号

型号	状况	推荐替代产品	封装	温度	RoHS/无铅
MAX849ESE	停止供货	MAX849ESE+	SOIC(N),；16引脚；61.9mm²	-40°C至+85°C	RoHS/无铅：否
MAX849ESE+	生产中		SOIC(N),；16引脚；61.9mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX849ESE+T	生产中		SOIC(N),；16引脚；61.9mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX849ESE-T	停止供货	MAX849ESE+T	N.SO；16引脚	-40°C至+85°C	参考数据资料

MAX848-MAX849.pdf MAX849

Linear Regulators in Portable Applications MAX883

典型工作电路 MAX849