The A6268 is a DC-to-DC converter controller, providing a
programmable constant current output for driving high power
LEDs in series. Driving the LEDs in series ensures identical
currents and uniform brightness. For automotive applications,
optimum performance is achieved when driving up to 15 LEDs
at currents up to 1 A.
The A6268 provides a cost-effective solution using an external
logic-level MOSFET and minimum additional external
components. The maximum LED current is set with a single
external sense resistor and can be modified using a current
reference input. Direct PWM control is possible via the Enable
input, which also provides a shutdown mode.
This DC-DC converter can be configured as a ground-referenced
boost converter or as a supply-referenced boost converter
providing buck-boost capability. The buck-boost topology used
ensures that there is no leakage path through the LEDs when
in shutdown and no inrush current at power-up.
Integrated diagnostics and two fault outputs give indication of
VIN and VREG undervoltage, chip overtemperature, output
open circuit, LED short circuit and LED undercurrent, and can
be configured to provide short to supply and short to ground
protection for the LED connections, LED overcurrent and
shorted LED string protection. A unique feature is the ability
to detect one or more shorted LEDs.
The device is provided in a 16-pin TSSOP package with exposed
thermal pad (suffix LP). It is lead (Pb) free, with 100% matte
tin leadframe plating.
Applications
- Automotive high power LED lighting systems
- Fog lights, reversing lights, daytime running lights
- Headlights
