AS1302-BTDT AMSCO [austriamicrosystems AG], AS1302-BTDT Datasheet - Page 13

• Manufacturer Part Number: AS1302-BTDT
• Description: 5V/30mA Adaptive Inductorless Boost Converter
• Manufacturer: AMSCO [austriamicrosystems AG]

AS1302
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
External Component Selection
The high internal oscillator frequency of 1.2MHz permits the use of small capacitors for both, the flying capacitors and
the output capacitors. For any given load the value of the flying- and output capacitors as well as their ESR are
affecting the output voltage performance.
In general, the capacitor’s ESR is inversely proportional to its physical size. Larger capacitances and higher voltage
ratings tend to reduce ESR. The ESR is a function of the frequency too, so it must be rated at the devices operating
frequency. Another factor affecting capacitor ESR is temperature.
Note: Many capacitors have a huge capacity variation over temperature. This can be compensated by choosing a
It is not critical which type of input bypass capacitor C
performance of the charge pump. Low ESR capacitors should be used to minimize V
capacitors are recommended since they have extremely low ESR and are available in small footprints.
Input Capacitor
A 2.2µF input bypass low ESR capacitor such as tantalum or ceramic is recommended to reduce noise and supply
transients. During startup and mode change it supplies a part of the peak input current drawn by the device.
Output Capacitor
The output capacitor is charged to V
in the output voltage waveform whenever the charge pump charges C
age of V
voltage ripple.
Table 4. Recommended Input and Output Capacitors
Figure 35. Load Regulation Comparision with different
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GRM188R61C225KE15
GRM21BR71E225KA73
GRM188R60J106ME47
GRM188R60J475KE19
5.15
5.05
4.95
4.85
5.1
4.9
5
Part Number
capacitor with a better thermal coefficient or by choosing a larger nominal value to ensure proper operation
over temperature.
OUT
0
Capacitors
. Therefore, ceramic or tantalum low ESR capacitors are recommended for C
5
2.2µF 16V 0603
2.2µF 25V 0805
4.7µF 6.3V 0603
10µF 6.3V 0603
Load Current (mA)
10
15
2.2µF
2.2µF
4.7µF
10µF
C
OUT
20
during the pumping phase. The ESR of the output capacitor introduces spikes
TC Code
X5R
X7R
X5R
X5R
25
30
Revision 1.02
BAT
Rated Voltage
and output filter capacitor C
Figure 36. Output Ripple vs. Output Current
6.3V
6.3V
16V
25V
100
80
60
40
20
0
0
49kHz
OUT
Comparision with different Capacitors
. These spikes contribute to the ripple volt-
5
Dimensions
1.2MHz
0603
0805
0603
0603
Load Current (mA)
10
OUT
OUT
15
ripple. Multi-layer ceramic
OUT
is used, but it will affect the
Murata
www.murata.com
to minimize the output
20
Manufacturer
2.2µF 16V 0603
2.2µF 25V 0805
4.7µF 6.3V 0603
10µF 6.3V 0603
25
13 - 18
30