Application information

ST619LB

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7

Application information

7.1

Charge pump capacitors C1 and C2

The values of charge pump capacitors C1 and C2 are critical to ensure adequate output

current and avoid excessive peak currents. It is suggested to use values in the range of 0.22

performance. Ceramic or tantalum capacitors are recommended.

7.2

Input and output capacitors C3 and C4

The type of input capacitor (C3) and output filter capacitor (C4) used is not critical, but it

does affect performance. Tantalum, ceramics or aluminium electrolytic are suggested. For

lowest ripple, use large, low effective series resistance (ESR) ceramic tantalum capacitors.

If the input supply source impedance is very low, C3 can be omitted. The typical application

circuit shows the component values for proper operation using minimal board space. The

input bypass capacitor (C3) and output filter capacitor (C4) should be at least 10 µF. Many

capacitors exhibit 40% to 50% variation over temperature. Compensate for capacitor

temperature coefficient by selecting a large nominal value to ensure proper operation over

temperature.

7.3

Layout consideration

In the below figure, the typical application evaluation board of ST619LB is reported. A good

layout ensures stability and helps maintain the output voltage under heavy loads. For best

performance, use very short connections to the capacitors.

Figure 14.

Typical application circuit