Maxim's MAX16834 is a current-mode high-brightness LED (HB LED) driver for boost, boost-buck, SEPIC, and high-side buck topologies. In addition to driving an n-channel power MOSFET switch controlled by the switching controller, it also drives an n-channel PWM dimming switch to achieve LED PWM dimming. The MAX16834 integrates all the building blocks necessary to implement a fixed-frequency HB LED driver with wide-range dimming control. The MAX16834 features constant-frequency peak current-mode control with programmable slope compensation to control the duty cycle of the PWM controller.
A dimming driver designed to drive an external n-channel MOSFET in series with the LED string provides wide-range dimming control up to 20 kHz. In addition to PWM dimming, the MAX16834 provides analog dimming using a DC input at REFI. The programmable switching frequency (100 kHz to 1 MHz) allows design optimization for efficiency and board space reduction. A single resistor from RT/SYNC to ground sets the switching frequency from 100 kHz to 1 MHz while an external clock signal at RT/SYNC disables the internal oscillator and allows the MAX16834 to synchronize to an external clock. The MAX16834's integrated high-side current-sense amplifier eliminates the need for a separate high-side LED current-sense amplifier in boost-buck applications.
The MAX16834 operates over a wide supply range of 4.75 V to 28 V and includes a 3 A sink/source gate driver for driving a power MOSFET in high-power LED driver applications. It can also operate at input voltages greater than 28 V in boost configuration with an external voltage clamp. The MAX16834 is also suitable for DC-DC converter applications such as boost or buck-boost. Additional features include external enable/disable input, an on-chip oscillator, fault indicator output (active-low FLT) for LED open/short or overtemperature conditions, and an overvoltage protection sense input (OVP+) for true overvoltage protection.
The MAX16834 is available in a thermally enhanced 4 mm x 4 mm, 20-pin TQFN-EP package and in a thermally enhanced 20-pin TSSOP-EP package and is specified over the automotive -40°C to +125°C temperature range.
Full size diagram
- Wide Input Operating Voltage Range (4.75 V to 28 V)
- Works for Input Voltage > 28 V with External Voltage Clamp on VIN for Boost Converter
- 3000:1 PWM Dimming/Analog Dimming
- Integrated PWM Dimming MOSFET Driver
- Integrated High-Side Current-Sense Amplifier for LED Current Sense in Boost-Buck Converter
- 100 kHz to 1 MHz Programmable High-Frequency Operation
- External Clock Synchronization Input
- Programmable UVLO
- Internal 7 V Low-Dropout Regulator
- Fault Output (Active-Low FLT) for Overvoltage, Overcurrent, and Thermal Warning Faults
- Programmable True Differential Overvoltage Protection
- 20-Pin TQFN-EP and TSSOP-EP Packages
- Architectural and Decorative Lighting (MR16, MR111)
- Automotive Rear and Front Lighting
- DC-DC Boost/Boost-Buck Converters
- Projection System RGB LED Light Sources
- Single-String LED LCD Backlighting
- Spot and Ambient Lights