LTM8020

10

8020fb

High Temperature Considerations

The die temperature of the LTM8020 must be lower than

the maximum rating of 125°C, so care should be taken

in the layout of the circuit to ensure good heat sinking of

the LTM8020. To estimate the junction temperature, ap-

proximate the power dissipation within the LTM8020 by

applying the typical efficiency stated in this datasheet to

the desired output power, or, if you have an actual module,

by taking a power measurement. Then calculate the inter-

nal temperature rise of the LTM8020 above the surface

of the printed circuit board by multiplying the module’s

power dissipation by the thermal resistance. The actual

thermal resistance of the LTM8020 to the printed circuit

board depends upon the layout of the circuit board, but the

thermal resistance given on page 2, which is based upon a

Characteristics can be used a guide.

Finally, be aware that at high ambient temperatures the

internal Schottky diode will have significant leakage current

increasing the quiescent current of the LTM8020.

BIAS Pin Considerations

The BIAS pin is used to provide drive power for the internal

power switching stage and operate internal circuitry. For

proper operation, it must be powered by at least 3V. If the

output voltage is programmed to be 3V or higher, simply

that the maximum voltage at the BIAS pin is both less than

power is applied from a remote or noisy voltage source, it

may be necessary to apply a decoupling capacitor locally

to the LTM8020.

APPLICATIONS INFORMATION

Figure 4. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures

Reliable Operation When the LTM8020 is Connected to a Live Supply

+

LTM8020

2.2μF

10V/DIV

10A/DIV

10V/DIV

10A/DIV

10V/DIV

10A/DIV

10μs/DIV

10μs/DIV

10μs/DIV

CLOSING SWITCH

SIMULATES HOT PLUG

(4a)

(4b)

(4c)

LOW

IMPEDANCE

ENERGIZED

24V SUPPLY

STRAY

INDUCTANCE

DUE TO 6 FEET

(2 METERS) OF

TWISTED PAIR

+

LTM8020

2.2μF

10μF

35V

AI.EI.

LTM8020

2.2μF

0.1μF

1Ω

8020 F04