LTM8060

14

Rev. 0

For more information www.analog.com

APPLICATIONS INFORMATION

(Ω)

BIAS

CFF

(Hz)

(Ω)

(Hz)

(Ω)

3V to 40V

0.8V Open 4.7µF 50V X5R 1206 2 × 100µF 4V X5R 0805

3.2V to 10V

100pF

400k

100k

600k

64.9k

3V to 40V

1V

1M

4.7µF 50V X5R 1206 2 × 100µF 4V X5R 0805

3.2V to 10V

100pF

400k

100k

725k

52.3k

3V to 40V

1.2V

499k 4.7µF 50V X5R 1206 2 × 100µF 4V X5R 0805

3.2V to 10V

68pF

500k

76.8k

875k

42.2k

3.2V to 40V

1.5V

287k 4.7µF 50V X5R 1206 2 × 100µF 4V X5R 0805

3.2V to 10V

–

600k

64.9k

1M

35.7k

3.5V to 40V

1.8V

200k 4.7µF 50V X5R 1206 1 × 100µF 4V X5R 0805

3.2V to 10V

–

650k

59k

1.3M

25.5k

3.5V to 40V

2V

165k 4.7µF 50V X5R 1206 1 × 100µF 4V X5R 0805

3.2V to 10V

–

700k

54.9k

1.4M

23.2k

4.2V to 40V

2.5V

118k 4.7µF 50V X5R 1206

1 × 47µF 4V X5R 0805

3.2V to 10V

–

800k

46.4k

1.7M

18.2k

5.5V to 40V

3.3V 78.7k 4.7µF 50V X5R 1206 1 × 47µF 6.3V X5R 0805 3.2V to 10V

–

1M

35.7k

2.2M

12.7k

8.5V to 40V

5V

47.5k 4.7µF 50V X5R 1206 1 × 47µF 6.3V X5R 1206 3.2V to 10V

–

1.2M

27.4k

3M

8.06k

11V to 40V

8V

27.4k 4.7µF 50V X5R 1206 1 × 47µF 10V X5R 1206

3.2V to 10V

–

1.6M

19.6k

3M

8.06k

Note 1: The LTM8060 may be capable of the operating at lower input voltages but may skip switching cycles.

Note 2: A bulk input capacitor is required.

Capacitor Selection Considerations

mum recommended values for the associated operating

conditions. Applying capacitor values below those indi-

cated in Table 1 is not recommended and may result in

undesirable operation. Using larger values is generally

acceptable, and can yield improved dynamic response,

if it is necessary. Again, it is incumbent upon the user to

verify proper operation over the intended system’s line,

load and environmental conditions.

Ceramic capacitors are small, robust and have very low

ESR. However, not all ceramic capacitors are suitable. X5R

and X7R types are stable over temperature and applied

voltage and give dependable service. Other types, includ-

ing Y5V and Z5U have very large temperature and voltage

coefficients of capacitance. In an application circuit they

may have only a small fraction of their nominal capaci-

tance resulting in much higher output voltage ripple

than expected.

Ceramic capacitors are also piezoelectric. In Burst Mode

operation, the LTM8060’s switching frequency depends

on the load current, and can excite a ceramic capacitor

at audio frequencies, generating audible noise. Since the

LTM8060 operates at a lower current limit during Burst

Mode operation, the noise is typically very quiet to a

casual ear.

If this audible noise is unacceptable, use a high perfor-

mance electrolytic capacitor at the output. It may also be

a parallel combination of a ceramic capacitor and a low

cost electrolytic capacitor.

A final precaution regarding ceramic capacitors concerns

the maximum input voltage rating of the LTM8060. A

ceramic input capacitor combined with trace or cable

inductance forms a high-Q (underdamped) tank circuit.

If the LTM8060 circuit is plugged into a live supply, the

input voltage can ring to twice its nominal value, possi-

bly exceeding the device’s rating. This situation is easily

avoided; see the Hot-Plugging Safely section.