MAX1687：升压型DC-DC转换器，提供精密的自适应限流，用于GSM

能够使GSM电池的峰值电流降低6倍，可消除发射过程中的DC-DC电源噪声，用户可选择禁止

The MAX1687/MAX1688 step-up DC-DC converters deliver up to 2W from a single Li-Ion or three NiMH cells. The devices are ideal for burst-load applications such as GSM cell phones and wireless LANs, where the RF power amplifiers require short, high current bursts. The MAX1687/MAX1688 reduce battery surge current by slowly charging a reservoir capacitor, which supplies the necessary peak energy for the load current burst. As a result, the peak battery current is limited, thus maximizing battery life and minimizing battery voltage sag and transient dips. An internal synchronous rectifier provides over 90% conversion efficiency and eliminates the need for an external Schottky diode. A logic shutdown mode reduces the shutdown current to only 3µA. The devices can be disabled during current bursts (RF transmit mode) to eliminate switching noise. The switching frequency of the MAX1687/MAX1688, controlled by the selected inductor, can exceed 1MHz. Two external resistors set the output voltage from 1.25V to 6V. The MAX1687 controls peak battery current, while the MAX1688 features a more advanced, adaptive constant-recharge-time algorithm that maximizes battery life. The MAX1687/MAX1688 are available in thin 16-pin TSSOP (1.1mm max height) or standard 8-pin SO packages.

关键特性

Low 450mA Peak Battery Current Provides 2A, 5V GSM Burst
90% Efficiency
Internal Power MOSFETs and Current-Sense Resistor
Output Disconnects from Input During Shutdown
3µA Shutdown Current
Precise Voltage-Controlled Current Limit (MAX1687)
Adaptive Constant-Recharge-Time Capability (MAX1688)
1.25V to 6V Adjustable Output
2.7V to 6V Input Range (1 Li-Ion cell or 3 NiMH cells)
Switching Frequency Can Exceed 1MHz
Standby Mode Disables DC-DC During Transmission Burst
Low Inrush Current at Start-Up

MAX1687、MAX1688：典型工作电路

应用

GSM电话
PC卡(PCMCIA)
无线手机

数据手册DataSheet

语言	下载文件	备注
英文	MAX1687-MAX1688.pdf	Rev 0; 02/1999

关键参数

Part Number	V_IN (V)	V_IN (V)	V_OUT1 (V)	V_OUT1 (V)	I_OUT1 (A)	Output Adjust. Method	Switch Type	Synchronous Switching	I_CC (mA)	Shutdown Mode Supply Current (µA)	DC-DC Outputs	Oper. Freq. (kHz)	Package/Pins	Budgetary Price
Part Number	min	max	min	max	max	Output Adjust. Method	Switch Type	Synchronous Switching	typ	typ	DC-DC Outputs	Oper. Freq. (kHz)	Package/Pins	See Notes
MAX1687	2.7	6	1.25	6	2.5	Resistor	Internal	Yes	2	3	1	500	SOIC(N)/8 TSSOP/16	$2.48 @1k
MAX1688	2.7	6	1.25	6	2.5	Resistor	Internal	Yes	2	3	1	500	SOIC(N)/8 TSSOP/16	$2.48 @1k

开发工具

质量和环境数据

MAX1687.pdf

订购型号

型号	状况	推荐替代产品	封装	温度	RoHS/无铅
MAX1687ESA	停止供货	MAX1687ESA+	SOIC(N),；8引脚；30.9mm²	-40°C至+85°C	RoHS/无铅：否
MAX1687ESA+	生产中		SOIC(N),；8引脚；30.9mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX1687ESA+T	生产中		N.SO；8引脚	-40°C至+85°C	参考数据资料
MAX1687ESA-T	停止供货	MAX1687ESA+T	N.SO；8引脚	-40°C至+85°C	参考数据资料
MAX1687EUE	最后一次购买		TSSOP,；16引脚；33.4mm²	-40°C至+85°C	RoHS/无铅：否
MAX1687EUE+	生产中		TSSOP,；16引脚；33.4mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX1687EUE+T	生产中		TSSOP,；16引脚；33.4mm²	-40°C至+85°C	RoHS/无铅：无铅
MAX1687EUE-T	停止供货	MAX1687EUE+T	TSSOP,；16引脚；33.4mm²	-40°C至+85°C	RoHS/无铅：否