AS3682

Data Sheet

Capacitor and Resistor Selection

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Revision 2.21

37 - 43

12 External Components

12.1 Capacitor and Resistor Selection

Use low-ESR ceramic capacitors with X7R or X5R dielectric – these capacitors allow good filtering and have a wide

temperature range. The connections of all external capacitors should be kept as short as possible.

All resistors should have a tolerance of ±1%.

12.2 Usage of PCB Wire Inductance

(EQ 1)

It is recommended to apply a minimum of 20nH (maximum 200nH) with low impedance. This inductance can be real-

ized on the PCB without any discrete coil. Assuming that 1mm signal line corresponds to approximately 1nH (valid if

the length (L) is significantly bigger than the width (W) of the line (L/W <10)). Thus a line length of:

20mm < L < 200mm

(EQ 2)

is recommended. The shape of the line is not important.

Figure 24. PCB Wire Inductance Example 1

Figure 25. PCB Wire Inductance Example 2

12.3 External Component Specifications

Notes:

1. See Usage of PCB Wire Inductance on page 37.

Table 39. External Components List

Part

Number

Value

Tol

(Min)

Rating

(Max)

Notes

Package

(Min)

Min

Typ

Max

2.2µF

±20%

6.3V

Ceramic, X5R

0603

C3

1µF

4.7µF

±20%

6.3V

Ceramic, X5R

0603

C4

1µF

±20%

6.3V

Ceramic, X5R

0603

C5

1µF

±20%

6.3V

Ceramic, X5R

0603

C6

2.2µF

±20%

6.3V

Ceramic, X5R

0603

R1

240k

Ω

±1%

Bias Resistor

0201

L

PIN VBAT

BATTERY

Connector

L_total=L

Cin

Cbat

GND

GND

PIN VBAT

BATTERY

Connector

Cin

Cbat

GND

GND

L1

L2

L_total=L1+10xL2