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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

产品详情

主要特征

应用/用途

Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 2.7
VIN (V) (max) 6
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 6
IOUT1 (A) (max) 2.5
Switch Type Internal
Output Adjust. Method Resistor
Synchronous Switching? Yes
ICC (mA) (typ) 2
Shutdown Mode Supply Current (µA) (typ) 3
# DC-DC Outputs 1
Switching Frequency (kHz) 500
Package/Pins TSSOP/16
Budgetary
Price (See Notes)
3.12
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参量

Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 2.7
VIN (V) (max) 6
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 6
IOUT1 (A) (max) 2.5
Switch Type Internal
Output Adjust. Method Resistor
Synchronous Switching? Yes
ICC (mA) (typ) 2
Shutdown Mode Supply Current (µA) (typ) 3
# DC-DC Outputs 1
Switching Frequency (kHz) 500
Package/Pins TSSOP/16
Budgetary
Price (See Notes)
3.12

主要特征

  • 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

应用/用途

  • GSM电话
  • PC卡(PCMCIA)
  • 无线手机

描述

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.

简化框图

MAX1687、MAX1688:典型工作电路 MAX1687、MAX1688:典型工作电路 Zoom icon

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在Maxim的知识库中搜索技术问题的答案

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Maxim的专业工程师团队也会为您解答相应的技术问题,请访问Maxim的 支持中心