AS3661 datasheet(83/87 Pages) AMSCO

83 / 87 page

www.austriamicrosystems.com

Revision 1.3

82 - 85

AS3661

Datasheet - Ty p i c a l A p p l i c a t i o n

9.1 Recommended External Components

The AS3661 requires 4 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors are

recommended. Tantalum and aluminium capacitors are not recommended because of their high ESR. For the flying

capacitors (C1 and C2) multi-layer ceramic capacitors should always be used. These capacitors are small, inexpensive

and have very low equivalent series resistance (ESR <20m

Ω typ.). Ceramic capacitors with X7R or X5R temperature

characteristic are preferred for use with the AS3661. These capacitors have tight capacitance tolerance (as good as

±10%) and hold their value over temperature (X7R: ±15% over -55°C to 125°C; X5R: ±15% over -55°C to 8 5°C).

Capacitors with Y5V or Z5U temperature characteristic are generally not recommended for use with the AS3661.

Capacitors with these temperature characteristics typically have wide capacitance tolerance (+80%, -20%) and vary

significantly over temperature (Y5V: +22%, -82% over -30°C to +85°C range; Z5U: +22%, -56% over +10°C to +85°C

range). Under some conditions, a nominal 1µF Y5V or Z5U capacitor could have a capacitance of only 0.1µF. Such

detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum capacitance requirements

of the AS3661. For proper operation it is necessary to have at least 0.24 µF of effective capacitance for each of the

flying capacitors under all operating conditions. The output capacitor CVCPOUT directly affects the magnitude of the

output ripple voltage. In general, the higher the value of CVCPOUT, the lower the output ripples magnitude. For proper

operation it is recommended to have at least 0.50µF of effective capacitance for CVBAT and CVCPOUT under all

operating conditions. The voltage rating of all four capacitors should be 6.3V; 10V is recommended. Recommended

External Components below lists recommended external components from some leading ceramic capacitor

manufacturers. It is strongly recommended that the AS3661 circuit be thoroughly evaluated early in the design-in

process with the mass-production capacitors of choice. This will help ensure that any variability in capacitance does

not negatively impact circuit performance.

Figure 37. Recommended External Components

Model

Type

Vendor

Voltage Rating

Package Size

1µF for CVBAT and CVCPOUT

C1005X5R1A105K

Ceramic X5R

TDK

10V

0402

LMK105BJ105KV-F

Ceramic X5R

Taiyo Yuden 10V

0402

ECJ0EB1A105M

Ceramic X5R

Panasonic

10V

0402

ECJUVBPA105

Ceramic X5R, array

of two

Panasonic

10V

0504

470F for CFLY1 and CFLY2

C1005X5R1A474K

Ceramic X5R

TDK

10V

0402

LMK105BJ474KV-F

Ceramic X5R

Taiyo Yuden 10V

0402

ECJ0EB0J474K

Ceramic X5R

Panasonic

6.3V

0402

LEDs

User defined. Note that D7, D8 and D9 outputs are

powered from VBAT when specifying the LEDs.

AS3661 Datasheet(PDF) 83 Page - ams AG

AS3661 Datasheet(HTML) 83 Page - ams AG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87

Datasheet Download

Link URL