MAX16840_15 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – LED Driver with Integrated MOSFET

MAX16840
EVALUATION KIT AVAILABLE
LED Driver with Integrated MOSFET
for MR16 and Other 12V AC Input Lamps
General Description
The MAX16840 is an LED driver IC for lighting applica-
tions. It includes all the necessary features to design low-
component-count LED drivers for 12V AC and 24V AC
input (e.g., MR16) light bulbs. A proprietary input-current
control scheme allows LED lamps based on this device
to be compatible with electronic transformers, and dim-
mable with standard trailing-edge dimmers (where elec-
tronic transformers are present).
The IC can be used in buck, boost, and buck-boost
topologies and features. It has an integrated 0.2I (max),
48V switching MOSFET.
The IC uses constant-frequency average current-mode
control. It senses the input current through the voltage
at the FB pin, and regulates its average. An input pin
(REFI) allows the setting of the input-current level. When
the voltage at this pin is set below a certain threshold, the
input current is proportional to this voltage, while when
that voltage is beyond the threshold, the input current is
set at a fixed, predefined level. This nonlinear behavior of
REFI allows its use to achieve thermal foldback, by con-
necting it to an NTC resistor.
The IC also features an internal overvoltage protection on
the IN pin to protect the internal switching MOSFET from
damage if the LED string is open or if the voltage on the
LED string is too high.
The IC has a separate EXT pin that can be used to guar-
antee that there is a kick-start of current at turn-on for low-
input voltages for proper operation with electronic trans-
formers. EXT drives an external npn transistor. Once the
UVLO threshold of 5.5V is crossed on IN, EXT is pulled
to ground and the external npn transistor is turned off.
The IC is available in a 3mm x 3mm, 10-pin TDFN power
package, and is rated over the -40NC to +125NC operat-
ing temperature range.
Applications
MR16 and Other 12V AC or DC Input LED
Lighting Applications
Benefits and Features
●● Cost-Effective Solution for MR16 and Other SSL
Applications
• Proprietary Input Current-Control Scheme to
Achieve Electronic Transformer Compatibility
and Dimmability
• Buck, Boost, SEPIC, and Buck-Boost
Topologies
• Analog Dimming
●● Minimal Component Count Saves Cost and Space
• Integrated 0.2Ω (max) 48V Switching MOSFET
●● Protection Features and Wide Operating Temperature
Range Improves Reliability
• Thermal-Foldback Protection
• Output Overvoltage Protection
• Internal Overtemperature Protection
• Available in a 10-Pin Thermally Enhanced TDFN
Package
• Operation Over -40°C to +125°C Temperature
Range
Ordering Information
PART
TEMP RANGE
MAX16840ATB+ -40NC to +125NC
PIN-PACKAGE
10 TDFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Typical Operating Circuit
L1
BD1
12V AC
L2
D1
R3
C1
DRAIN
REFI
IN
EXT ^MAX16840
COMP
C4
SOURCE
FB
GND
R2
LED-
C2
LED+
R1
19-5671; Rev 4; 1/15