Allegro Microsystems ALT80800

Description

The ALT80800 is a synchronous buck switching regulator that provides constant-current output to drive high-power LEDs. It integrates both high-side and low-side N-channel DMOS switches for DC-to-DC step-down conversion. A true average current is output using a cycle-by-cycle, controlled on-time method. Output current is user-selectable by an external current sense resistor. Output voltage is automatically adjusted to drive various numbers of LEDs in a single string. This ensures the optimal system efficiency. LED dimming is accomplished by a direct logic input pulsewidth modulation (PWM) signal at the PWM pin while EN is enabled. Alternatively, applying a PWM signal at the EN pin while PWM pin is high can enable “chopped battery” PWM dimming for legacy control modules. Furthermore, an Analog Dimming input (ADIM pin) can be used, for example, to calibrate the LED current or implement thermal foldback in conjunction with external NTC thermistor. The ALT80800 is provided in a 16-pin TSSOP (suffix LP), with exposed pad for enhanced thermal dissipation.

Features

• AEC-Q100 qualified
• Supply voltage 4.5 to 55 V
• 2.0 A maximum output over operating temperature range
• Integrated high-side and low-side MOSFETs: 200 mΩ / 150 mΩTYP
• True average output current control
• Internal control loop compensation
• Integrated 5 V, 14 mA LDO regulator for peripheral circuits
• Dimming via PWM pin or EN pin down to 0.1% at 200 Hz
• Analog dimming (ADIM pin) for brightness calibration and thermal foldback
• Low-power shutdown (1 μA typical)
• Cycle-by-cycle current limit
• Active low fault flag output
• LED open fault mask setting for low VIN operation
• Undervoltage lockout (UVLO) and thermal shutdown protection
• Switching frequency dithering for improved EMC
• Robust protection against: Adjacent pin-to-pin short, Pin-to-ground short, Component open/short faults

Typical applications

• Automotive lighting/ Daytime running lights/ Front and rear fog lights/ Turn/stop lights/ Map light/ Dimmable interior lights

More information

• Datasheet