AAT3183 Datasheet, PDF (12/16 Pages) Advanced Analogic Technologies – 300mA Inductorless Step-Down Converter

AAT3183
300mA Inductorless Step-Down Converter
The input capacitor (C_IN) is required to maintain low
input voltage ripple as well as minimize noise cou-
pling to nearby circuitry. The size of the required
input capacitor can vary, and depends on the
source impedance of the input voltage source. A
small 1µF to 2.2µF MLC input capacitor is suitable
in most applications. MLC capacitors sized as
small as 0402 are available which meet these
requirements.
The flying capacitor (C_FLY) transfers energy to the
output during both ‘charge’ and ‘discharge’ inter-
vals. C_FLY is sized to maintain the maximum output
load and maintain acceptable output voltage ripple
at the minimum input voltage.
The ratio C_OUT to C_FLY is determined by the input to
output voltage ratio and should be maintained near
5:1 for best performance across the operating range.
Input Capacitor
Output Capacitor
Input [1µF(min)] and
Flying Capacitors
Size
0402
0603
C_IN (µF/V)
2.2/6.3
4.7/6.3
Size
0603
0603
C_OUT (µF/V)
2.2/6.3
4.7/6.3
Size
0402
0402
C_FLY (µF/V)
0.47/10
1/10
Table 1: AAT3183 Capacitor Size Selection Chart
(see Table 2 for corresponding manufacturer part numbers).
Maximum
Output Current
I_OUT (mA)
220
300
Input and Output Capacitors
C_IN/
C_OUT
Value
2.2µF
4.7µF
2.2µF
4.7µF
2.2µF
4.7µF
Voltage
(size)
16V
(0603)
10V
(0603)
16V
(0603)
6.3V
(0603)
16V
(0603)
10V
(0603)
Mfg
TDK
TDK
Murata
Murata
Taiyo-Yuden
Taiyo-Yuden
Part Number
C1608X5R1C225K
C1608X5R1A475K
GRM188R61C225K
GRM188R60J475K
EMK107BJ225KA
LMK107BJ475KA
Input [1µF(min)] and Flying Capacitors
C_FLY
Value
0.47µF
1µF
0.47µF
1µF
0.47µF
1µF
Voltage
(size)
10V
(0402)
10V
(0402)
10V
(0402)
10V
(0402)
10V
(0402)
16V
(0603)
Mfg
TDK
TDK
Murata
Murata
Taiyo-Yuden
Taiyo-Yuden
Part Number
C1005X5R1A474K
C1005X5R1A105K
GRM155R61A474K
GRM155R61A105K
LMK105BJ474KV
EMK107BJ105KA
Table 2: Ceramic Capacitors for the 300mA AAT3183 Step-Down Charge Pump Converter.
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3183.2007.07.1.2