A6271is a new DC-DC converter controller that provides a programmable constant-current output to drive high power series LEDs. shouldcontrollerBased on a programmable fixed-frequency, peak current-mode control architecture. DC-DC converters can be set in a variety of different switch configurations, including boost, buck-boost, SEPIC and buck (ground-referenced switch).
The A6271 provides a cost-effective solution with external logic-level MOSFETs and minimal external components. The maximum LED current can be set using a separate external sense resistor and can be precisely adjusted using a current reference input (analog control). External PWM dimming is available via the PWMIN input, and a shutdown mode is provided. As an alternative, the PWMIN and DR pins can be programmed to use internal PWM dimming circuitry. Either PWM scheme can control the PWMOUT output, which drives external p-channel MOSFETs connected in series to LED strings. This MOSFET also isolates the load during certain fault conditions, including output short-to-ground.
The A6271 has been carefully designed to minimize electromagnetic emissions through distributed decoupling and externally programmable frequency jitter circuitry configured as required by the EMI specification CISPR 25. The basic switching frequency can also be set below 150 kHz as required by most EMI standards.
The A6271 has comprehensive integrated protection to protect against faults in ICs, LED driver systems, and LED strings. Fixed output overvoltage protection ensures that the maximum voltage rating is not exceeded even when a single point of fault occurs in the programmable output overvoltage protection circuit. Other protection features include: LED overload (boost, SEPIC), output undervoltage (buck or buck-boost), input supply (VIN) undervoltage, 5 V regulator (VREG) output undervoltage, high-side power supply (PWM PMOS) undervoltage, and thermal protection.
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- High-power LED lighting systems for vehicles
- Fog lights, reversing lights, daytime running lights (DRL), position lights, and headlights.
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- AEC – Q100 compliant for the automotive industry
- Constant current LED driver
- 4.5 V - 50 V power supply
- LED string maximum voltage 53.3 V
- Boost, buck-boost, SEPIC and buck switching converters
- 70 kHz - 700 kHz programmable switching frequency
- PWM-controlled PMOS drivers drive LEDs
- Current control at low duty cycles
- Dimming via external PWM, internal PWM, and/or analog dimming functions
- Frequency jitter schemes effectively spread the spectrum to reduce electromagnetic interference
- Comprehensive fault protection and fault flagging