MAX840是Maxim美信半导体公司的一款电荷泵产品，MAX840是低噪声、稳压型、-2V GaAsFET偏置电源，本站介绍了MAX840的封装应用图解、特点和优点、功能等，并给出了与MAX840相关的Maxim元器件型号供参考。
MAX840 - 低噪声、稳压型、-2V GaAsFET偏置电源 - 电荷泵 - 可使用小电容工作，低至0.22µF - 美信半导体
The MAX840/MAX843/MAX844 low-noise, inverting charge-pump power supplies are ideal for biasing GaAsFETs in cellular telephone transmitter amplifiers. They operate with inputs down to 2.5V.
The MAX840 offers both a -2V preset output and a -0.5V to -9.4V adjustable output. The MAX843/MAX844 use an external positive control voltage to set the negative output voltage. Input voltage range for all the devices is 2.5V to 10V, and output current is 4mA with VIN > 2.7V. These circuits can operate with small capacitors, as low as 0.22µF.
An internal linear regulator reduces the MAX840's output voltage ripple to 1mVp-p. With a well-filtered control voltage (VCTRL), the MAX843/MAX844 also achieve less than 1mVp-p typical output ripple. Supply current is 750µA, and reduces to less than 1µA in shutdown (MAX840/MAX843). The MAX844's unregulated output is active in shutdown, with the charge pump switching at 20kHz. It provides a low-power LCD supply.
