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AS1341

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

Output Capacitor

Choose the output capacitor to service the maximum load current with acceptable voltage ripple. The output ripple has

two components: variations in the charge stored in the output capacitor with each LX pulse, and the voltage drop

across the capacitor’s equivalent series resistance (ESR) caused by the current into and out of the capacitor:

(EQ 7)

The output voltage ripple as a consequence of the ESR and output capacitance is:

(EQ 8)

Where:

Equations 7, 8, and 9 are suitable for initial capacitor selection, but actual values should be set by testing a prototype

or evaluation circuit. As a general rule, a smaller amount of charge delivered in each pulse results in less output ripple.

Since the amount of charge delivered in each oscillator pulse is determined by the inductor value and input voltage, the

voltage ripple increases with larger inductance, and as the input voltage decreases.

Input Capacitor

The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple on

imposed by the switching current defined as:

(EQ 10)

For most applications, non-tantalum type (ceramic, aluminum, polymer, or OS-CON) are preferred due to their robust-

ness to high in-rush currents typical of systems with low-impedance battery inputs. Alternatively, connect two (or more)

smaller value low-ESR capacitors in parallel to reduce cost. Choose an input capacitor that exhibits less than +10ºC

temperature rise at the RMS input current for optimal circuit life.

Table 6. Recommended Output Capacitor

Part Number

C

ESR

Rated Voltage

Circuit

Manufacturer

T520V107M010ATE018

100µF

18m

Ω

10V

1, 2

Kemet

www.kemet.com

A700V826M006ATE018

82µF

18m

Ω

6.3V

1, 2

T520B107M006ATE040

100µF

40m

Ω

6V

1, 2

T520A336M006ATE070

33µF

70m

Ω

6.3V

3, 4

A700V226M006ATE028

22µF

28m

Ω

6.3V

3, 4

510X107M020ATE040

10µF

40m

Ω

20V

5

EEFUD0J101R

100µF

15m

Ω

6.3V

1, 2

Panasonic

www.panasonic.com

EEFCD0K330R

33µF

18m

Ω

8V

3, 4

10TPB100ML

100µF

55m

Ω

10V

1, 2

Sanyo

www.edc.sanyo.com

6TPB47M

47µF

70m

Ω

6.3V

3, 4

Table 7. Recommended Input Capacitor

C

TC Code Rated Voltage

Circuit

Manufacturer

10µF

X7R

25V

1-5

Murata www.murata.com

Taiyo Yuden www.t-yuden.com

Kemet www.kemet.com

Panasonic www.panasonic.com

Sanyo www.edc.sanyo.com