LTM8055

10

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For more information www.linear.com/LTM8055

APPLICATIONS INFORMATION

For most applications, the design process is straight for-

ward, summarized as follows:

1. Look at Table 1 and find the row that has the desired

input range and output voltage.

values.

3. Apply the output sense resistor to set the output current

resistor in ohms.

Whilethesecomponentcombinationshavebeentestedfor

proper operation, it is incumbent upon the user to verify

proper operation over the intended system’s line, load and

environmental conditions. Bear in mind that the maximum

output current is limited by junction temperature, the rela-

tionship between the input and output voltage magnitude

and other factors. Please refer to the graphs in the Typical

Performance Characteristics section for guidance.

which the LTM8055 should be allowed to switch is given

There are additional conditions that must be satisfied if

the synchronization function is used. Please refer to the

Synchronization section for details.

Note that Table 1 calls out both ceramic and electrolytic

output capacitors. Both of the capacitors called out in

the table must be applied to the output. The electrolytic

capacitors in Table 1 are described by voltage rating,

value and ESR. The voltage rating of the capacitor may

be increased if the application requires a higher voltage

stress derating. The LTM8055 can tolerate variation

in the ESR; other capacitors with different ESR may

be used, but the user must verify proper operation

over line, load and environmental conditions. Table 2

gives the description and part numbers of electrolytic

capacitors used in the LTM8055 development testing and

design validation.

5V to 24V

3.3V 2 × 4.7µF, 50V, X5R, 0805 22µF, 6.3V, X5R, 0805

100µF, 6V, 75mΩ, Electrolytic

100k/56.2k

600

36.5k

800

24.9k

5V to 28V

5V 2 × 4.7µF, 50V, X5R, 0805 22µF, 6.3V, X5R, 0805

100µF, 6V, 75mΩ, Electrolytic

100k/31.6k

550

39.2k

800

24.9k

5V to 31V

8V 2 × 4.7µF, 50V, X5R, 0805 47µF, 10V, X5R, 1206

100µF, 16V, 100mΩ, Electrolytic

100k/17.4k

500

45.3k

800

24.9k

5V to 36V

12V 2 × 4.7µF, 50V, X5R, 1210 22µF, 25V, X5R, 0805

68µF, 16V, 200mΩ, Electrolytic

100k/11k

600

36.5k

800

24.9k

5V to 36V

18V 2 × 4.7µF, 50V, X7R, 1210 2 x 22µF, 25V, X5R, 1210

47µF, 25V, 900mΩ, Electrolytic

100k/6.98k

500

45.3k

800

24.9k

5V to 36V

24V 2 × 4.7µF, 50V, X7R, 1210 22µF, 25V, X5R, 1210

33µF, 35V 300mΩ, Electrolytic

100k/5.23k

650

31.6k

800

24.9k

5.5V to 36V

36V 2 × 4.7µF, 50V, X7R, 1210 10µF, 50V, X5R, 1206

10µF, 50V 120mΩ, Electrolytic

100k/3.40k

650

31.6k

800

24.9k

Notes: An input bulk capacitor is required. The output capacitance uses a combination of a ceramic and electrolytic in parallel. Other combinations of

resistor values for the RFB network are acceptable.

Table 2. Electrolytic Caps Used in LTM8055 Testing

DESCRIPTION

MANUFACTURER

PART NUMBER

100µF, 6V, 75mΩ, Tantalum C Case

AVX

TPSC107M006R0075

100µF, 16V, 100mΩ, Tantalum Y Case

AVX

TPSY107M016R0100

68µF, 16V, 200mΩ, Tantalum C Case

AVX

TPSC686M016R0200

47µF, 25V, 900mΩ, Tantalum D Case

AVX

TAJD476M025R

33µF, 35V, 300mΩ, Tantalum D Case

AVX

TPSD336M035R0300

10µF, 50V, 120mΩ, Aluminum 6.3 × 6mm case

Suncon

50HVP10M