LT8300
applicaTions inForMaTion
Step 7: Select the EN/UVLO Resistors.
Step 8: Ensure minimum load.
Determinetheamountofhysteresisrequiredandcalculate
R1 resistor value:
The theoretical minimum load can be approximately
estimated as:
300µH•(52mA)2 • 7.5kHz
V
= 2.5µA • R1
IN(HYS)
ILOAD(MIN)
=
= 0.25mA
Example:
2 •12V
Choose 2.5V of hysteresis,
R1 = 1M
Remembertochecktheminimumloadrequirementinreal
application. The minimum load occurs at the point where
the output voltage begins to climb up as the converter
delivers more energy than what is consumed at the out-
put. The real minimum load for this application is about
0.6mA, 0.5% of 120mA maximum load. In this example,
a 20k resistor is selected as the minimum load.
Determine the UVLO thresholds and calculate R2 resistor
value:
1.239V •(R1+ R2)
V
=
+ 2.5µA •R1
IN(UVLO+ )
R2
Example:
Set V UVLO rising threshold to 34.5V,
IN
R2 = 40.2k
V
V
= 34.1V
= 31.6V
IN(UVLO+)
IN(UVLO–)
8300f
19
Linear [ Linear ]
