LTM8020EV-PBF LINER [Linear Technology], LTM8020EV-PBF Datasheet - Page 10

• Manufacturer Part Number: LTM8020EV-PBF
• Description: 200mA, 36V DC/DC ?Module
• Manufacturer: LINER [Linear Technology]

LTM8020
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 effi ciency 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
25cm
Characteristics can be used a guide.
APPLICATIONS INFORMATION
10
2
4-layer FR4 PC board, and the Typical Performance
IMPEDANCE
24V SUPPLY
ENERGIZED
LOW
Figure 4. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures
Reliable Operation When the LTM8020 is Connected to a Live Supply
+
SIMULATES HOT PLUG
CLOSING SWITCH
AI.EI.
0.1μF
10μF
35V
STRAY
INDUCTANCE
DUE TO 6 FEET
(2 METERS) OF
TWISTED PAIR
+
I
IN
1Ω
V
IN
2.2μF
2.2μF
2.2μF
LTM8020
LTM8020
LTM8020
(4a)
(4b)
(4c)
10V/DIV
10A/DIV
10V/DIV
10A/DIV
10V/DIV
10A/DIV
Finally, be aware that at high ambient temperatures the
internal Schottky diode will have signifi cant 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
tie BIAS to V
to V
that the maximum voltage at the BIAS pin is both less than
25V and the sum of V
power is applied from a remote or noisy voltage source, it
may be necessary to apply a decoupling capacitor locally
to the LTM8020.
V
V
V
I
I
I
IN
IN
IN
IN
IN
IN
IN
or some other voltage source. In all cases, ensure
OUT
. If V
10μs/DIV
10μs/DIV
10μs/DIV
OUT
IN
and BIAS is less than 47V. If BIAS
is less than 3V, BIAS can be tied
8020 F04
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