www.austriamicrosystems.com/DC-DC_Step-Down/AS1332

Revision 1.02

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AS1332

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

External Component Selection

Inductor Selection

For the external inductor, a 3.3µH inductor is recommend. Minimum inductor size is dependant on the desired effi-

ciency and output current. Inductors with low core losses and small DCR at 2MHz are recommended.

Capacitor Selection

recommend as they retain capacitance over wide ranges of voltages and temperatures.

Input and Output Capacitor Selection

Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Also low

have extremely low ESR and are available in small footprints.

For input decoupling the ceramic capacitor should be located as close to the device as practical. A 4.7µF input capaci-

tor is sufficient for most applications. Larger values may be used without limitations.

A 2.2µF to 10µF output ceramic capacitor is sufficient for most applications. Larger values up to 22µF may be used to

obtain extremely low output voltage ripple and improve transient response.

EN Pin Control

Drive the EN pin using the system controller to turn the AS1332 ON and OFF. Use a comparator, Schmidt trigger or

logic gate to drive the EN pin. Set EN high (>1.2V) for normal operation and low (<0.5V) for a 0.01µA (typ.) shutdown

mode. Set EN low to turn off the AS1332 during power-up and under voltage conditions when the power supply is less

than the 2.7V minimum operating voltage. The part is out of regulation when the input voltage is less than 2.7V.

Table 6. Recommended Inductors

Part Number

L

DCR

Current Rating Dimensions (L/W/T)

Manufacturer

LPS4018-222ML_

2.2µH

0.070Ω

2.9A

3.9x3.9x1.7mm

Coilcraft

www.coilcraft.com

LPS4018-332ML_

3.3µH

0.080Ω

2.4A

3.9x3.9x1.7mm

LPS4018-472ML_

4.7µH

0.125Ω

1.9A

3.9x3.9x1.7mm

Table 7. Recommended Capacitors for the Step-Down Converter

Part Number

C

Voltage

Type

Size

Manufacturer

GRM21BR60J226ME39

22µF

6.3V

X5R

0805

Murata

www.murata.com

GRM21BR60J106KE01

10µF

6.3V

X5R

0805

GRM21BR61C475KA88

4.7µF

16V

X5R

0805

GRM188R61C225KE15

2.2µF

16V

X5R

0603

GRM188R61A225KE34

2.2µF

10V

X5R

0603

C0603C475K8PAC7867

4.7µF

10V

X5R

0603

KEMET

www.kemet.com