a first-order approximation, the LED voltage is assumed

constant. The duty cycle at the peak of the input voltage

is, therefore:

×

= −

= −

+

+

×

MIN

LED

LED

13.2V

2

18.66V

D1

1

V

18.66V

V

13.2V

2

to 60% range of the maximum input current. Assuming a

current is given by:

The minimum inductor value is given by:

2

MIN

MIN

IN

18.66V D

L

0.6I

300kHz

×

=

×

where the switching frequency is 300kHz. The saturation

Output Diode (D1)

A Schottky diode must be used as rectifier diode D1 to

reduce power dissipation. The voltage rating of diode D1

must be greater than the maximum peak input voltage

plus the maximum output voltage. Choose a diode that

minimizes dissipation at temperatures in the +90NC to

+100NC range. The diode should be selected to minimize

reverse leakage at the maximum output voltage while

minimizing forward losses when the diode is conducting.

Package Information

For the latest package outline information and land patterns (foot-

prints), go to www.maximintegrated.com/packages. Note that a

“+”, “#”, or “-” in the package code indicates RoHS status only.

Package drawings may show a different suffix character, but the

drawing pertains to the package regardless of RoHS status.

PACKAGE

TYPE

PACKAGE

CODE

OUTLINE

NO.

LAND

PATTERN NO.

10 TDFN-EP

T1033+1

21-0137

90-0003

MAX16840

LED Driver with Integrated MOSFET

for MR16 and Other 12V AC Input Lamps

www.maximintegrated.com

MaximIntegrated│ 11