LM2662, LM2663

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SNVS002E – JANUARY 1999 – REVISED OCTOBER 2014

Typical Applications (continued)

The peak-to-peak output voltage ripple is determined by the oscillator frequency, and the capacitance and ESR

(2)

Again, using a low ESR capacitor will result in lower ripple.

9.2.1.2.1

Paralleling Devices

Any number of LM2662 devicess (or LM2663 devices) can be paralleled to reduce the output resistance. Each

Figure 18. The composite output resistance is:

(3)

Figure 18. Lowering Output Resistance by Paralleling Devices

9.2.1.2.2

Cascading Devices

Cascading the LM2662 devices (or LM2663 devices) is an easy way to produce a greater negative voltage (as

shown in Figure 19). If n is the integer representing the number of devices cascaded, the unloaded output

(4)

A three-stage cascade circuit shown in Figure 20 generates

Cascading is also possible when devices are operating in doubling mode. In Figure 21, two devices are

An example of using the circuit in Figure 20 or Figure 21 is generating +15 V or

−15 V from a +5-V input.

Note that, the number of n is practically limited since the increasing of n significantly reduces the efficiency and

increases the output resistance and output voltage ripple.

Figure 19. Increasing Output Voltage by Cascading Devices

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