LM2665

SD

V+

CAP+

OUT

GND

OSCILLATOR

Switch Array

Switch Drivers

CAP-

8

LM2665

SNVS009H – NOVEMBER 1999 – REVISED MARCH 2016

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8 Detailed Description

8.1 Overview

The LM2665 CMOS charge-pump voltage converter operates as a voltage doubler for an input voltage in the

range of 2.5 V to 5.5 V. Two low-cost capacitors and a diode (needed during start-up) are used in this circuit to

provide up to 40 mA of output current. The LM2665 can also work as a voltage divider to split a voltage in the

range of 1.8 V to 11 V in half.

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Circuit Description

The LM2665 contains four large CMOS switches which are switched in a sequence to double the input supply

voltage. Energy transfer and storage are provided by external capacitors. Figure 10 illustrates the voltage

MOSFET switches and the ESR of the capacitors) and the charge transfer loss between capacitors. Details are

discussed in Application and Implementation.

Figure 10. Voltage Doubling Principle

8.4 Device Functional Modes

8.4.1 Shutdown Mode

A shutdown (SD) pin is available to disable the device and reduce the quiescent current to 1 µA. In normal

operating mode, the SD pin is connected to ground. The device can be brought into the shutdown mode by

applying to the SD pin a voltage greater than 40% of the V+ pin voltage.