MAX16821A

The MAX16821A pulsewidth-modulation (PWM) LED driver controllers provide high output-current capability in a compact package with a minimum number of external components. The MAX16821A is suitable for use in synchronous and nonsynchronous step-down (buck), boost, buck-boost, SEPIC, and Cuk LED drivers. A logic input (MODE) allows the devices to switch between synchronous buck and boost modes of operation. These devices are the first high-power drivers designed specifically to accommodate common-anode HBLEDs.

Features of the MAX16821A are:(1)up to 30A output current; (2)true-differential remote output sensing; (3)average current-mode control; (4)4.75V to 5.5V or 7V to 28V input-voltage range; (5)thermal shutdown; (6)nonlatching output overvoltage protection; (7)low-side buck mode with or without synchronous rectification; (8)high-side buck and low-side boost mode with or without synchronous rectification; (9)125kHz to 1.5MHz programmable/synchronizable switching frequency; (10)integrated 4A gate drivers; (11)clock output for 180° out-of-phase operation for second driver.The ICs offer average current-mode control that enable the use of MOSFETs with optimal charge and on-resistance figure of merit, thus minimizing the need for external heatsinking even when delivering up to 30A of LED current.

The absolute maximum ratings of the MAX16821A can be summarized as:(1)IN to GND:-0.3V to +30V;(2)storage temperature range:-65 to +150;(3)operating temperature range:-40 to +125;(4)junction temperature:+150;(5)continuous power dissipation:2758mW.Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied.Exposure to absolute maximum rating conditions for extended periods may affect device reliability.The VEA sets the gain of the voltage control loop, and determines the error between the differential amplifier output and the internal reference voltage. The VEA output clamps to 0.93V relative to the internal commonmode voltage, VCM (+0.6V), limiting the average maximum current. The maximum average current-limit threshold is equal to the maximum clamp voltage of the VEA divided by the gain (34.5) of the current-sense amplifier. This results in accurate settings for the average maximum current.