Smallest` package
Packaged in a tiny 3-by-3mm TDFN, these devices are said to be the smallest LED drivers to provide LED-driver designs with such a wide power range. Moreover, a high-voltage current-sense amplifier and up to 2MHz switching frequency further reduce space and component-count requirements. These highly integrated devices minimize power dissipation, increase reliability and reduce manufacturing costs, making them suitable for light sources such as the energy-efficient LED MR16 (an alternative to the traditional halogen MR16) and front and rear automotive lighting (RCL, DRL and fog/low-beam lights).
Unlike the general-purpose buck controllers most commonly used to power HB LEDs, the MAX16819/MAX16820 LED drivers employ hysteretic control. With this control technique, the drivers ensure rapid transient response and turn-on/-off times during PWM dimming, which translates into a wide dimming range (up to 5000:1) or the ability to dim at very high switching frequencies (up to 20kHz) using a dedicated DIM input. Hysteretic control also offers a high level of input-supply rejection, as well as rapid response during LED dimming. There is no control-loop compensation, which simplifies the design and further minimizes component count.
High-side current sensing
High-side current sensing further differentiates these drivers from standard buck PWM controllers. Because the voltage drop across the external sense resistor is only 200mV, the MAX16819/MAX16820 reduce power dissipation. In addition, the high-side current sensing and integrated current-setting circuitry minimize the number of external components while delivering an LED current with ±5 percent accuracy. The MAX16819 and MAX16820 offer 30 percent and 10 percent LED current ripple, respectively, without the use of an output capacitor.
A wide input-voltage range (4.5V to 28V) allows the MAX16819/MAX16820 to be optimized for different input-voltage standards in architectural and ambient lighting, and ensures cold-start and load dump compliance in automotive applications. These LED drivers are specified for the automotive temperature range (-40°C to 125°C) and are available in a Pb-free, 3-by-3mm, 6-pin TDFN package with exposed pad. Prices start at 58 cents (1,000-up, FOB USA).
Specifications:
- High-Side Current Sense
- Dedicated Dimming Control Input
- 20kHz Maximum Dimming Efficiency
- Hysteretic Control: No Compensation
- Up to 2MHz Switching Frequency
- ±5% LED Current Accuracy
- Adjustable Constant LED Current
- 4.5V to 28V Input Voltage Range
- Over 25W Output Power
- 5V, 10mA On-Board Regulator
- -40°C to +125°C Operating Temperature Range
