AS1341
Datasheet - Application Information
9.7 Input Capacitor
The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple on the input caused by the
circuit’s switching. The input capacitor must meet the ripple-current requirement (IRMS) imposed by the switching current defined as:
IRMS = (ILOAD x VOUTPUT)/VIN
x
√((4/3) x (VIN - VOUTPUT) - 1)
(EQ 10)
For most applications, non-tantalum type (ceramic, aluminum, polymer, or OS-CON) are preferred due to their robustness 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 7. Recommended Input Capacitor
C
TC Code
Rated Voltage
Manufacturer
Murata www.murata.com
Taiyo Yuden www.t-yuden.com
Kemet www.kemet.com
Panasonic www.panasonic.com
Sanyo www.edc.sanyo.com
10µF
X7R
25V
9.8 Diode Selection
The current in the D1 (see Figure 22 on page 10) changes abruptly from zero to its peak value each time the LX switch turns off. To avoid
excessive losses, the diode must have a fast turn-on time and a low forward voltage.
Note: Ensure that the diode peak current rating exceeds the peak current limit set by the current limit (see Setting Current Limit on page 11),
and that its breakdown voltage exceeds VIN. Schottky diodes are recommended.
9.9 Stable Operation
A well-designed system and selection of high-quality external components can eliminate excessive noise on pins OUT, FB, or GND, which can
lead to unstable device operation. Instability typically manifests itself as grouped switching pulses with large gaps and excessive low-frequency
output ripple (motorboating) during no-load or light-load conditions.
9.10 Recommended Components
Table 8. Recommended Components
Input Voltage
Output Voltage
ILIMIT
Inductor
Output Capacitor
MSS6132-103ML
LQH66SN-100M03
LQH55DN-150M03
CDRH6D28NP-150
T520V107M010ATE018
A700V826M006ATE018
T520B107M006ATE040
EEFUD0J101R
4.5V to 20V
1.25V to 5V
High
CDRH5D18NP-4R1
LPS4018-472ML
10TPB100ML
4.5v to 12V
4.5V to 20V
MSS6132-393ML
CDRH6D28NP-470
LQH66SN-470M03
LQH55DN-470M03
EEFCD0K330R
6TPB47M
T520A336M006ATE070
A700V226M006ATE028
1.25V to 5V
Low
MSS6132-103ML
LPS4018-223ML
CDRH5D18NP-220
4.5V to 12V
6V to 20V
5V to VIN
High or Low
See Inductors above
510X107M020ATE040
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