/a>LM3463″ title=”LM3463″>LM3463″ title=”LM3463″>LM3463 is a four-channel high-voltage LED driver. The input voltage of LM3464 is 12V-80V, and the input voltage of LM3464A is 12V-95V. The four outputs can be independently current stable High precision between channels, digital PWM or analog dimming control interface, dynamic headroom control to maximize efficiency, mainly used for street lighting and solid-state lighting solutions. This article introduces the main features, block diagrams, typical application circuit diagrams of LM3464/64A, main features of LM3464 4-way LED driver evaluation board, circuit diagrams, bill of materials and PCB component layout diagrams.
LM3464/64A is a 4-channel high-voltage current stabilizer with 4 separate current stabilizer channels, which work in conjunction with external N-channel MOSFETs and sense resistors to provide accurate drive current for each LED string. In addition, the dynamic headroom control (DHC) output can be connected to an external power supply in order to adjust the LED power supply voltage to the lowest level that is sufficient to keep all the light strings in a regulated state, so as to achieve the best overall efficiency.
Digital PWM or analog voltage signals can be used to control the duty cycle of all channels. When using analog control, the dimming frequency can be programmed through an external capacitor. Provides minimum duty cycle control when analog dimming is configured as thermal feedback.
Protection features include VIN undervoltage lockout, LED open/short circuit protection, and sending a fault signal to the system controller in the event of overheating.
Figure 1 Block diagram of LM3464/64A
Main features of LM3464/64A
• Wide input voltage range
• Dynamic headroom control can ensure the highest efficiency
• 4 output channels with independent current adjustment function
• High accuracy between channels
• Digital PWM/analog dimming control interface
• Resistor programmable dimming frequency and minimum duty cycle (analog dimming mode)
• Direct interface to thermal sensor
• Overheating protection
• Thermal shutdown
• Undervoltage lockout
• Thermally enhanced eTSSOP-28 package
Figure 2 LM3464/64A typical application circuit diagram
• Street lights
• Solid-state lighting solutions
LM3464 4-channel LED driver evaluation board
LM3464 is a linear LED driver with dynamic headroom control (DHC) technology, designed to drive 4 serial high-power/high-brightness LED strings. Four independent linear current regulators using low-end N-channel MOSFETs realize LED current regulation. DHC can automatically optimize system efficiency while maintaining a stable and accurate LED current. LM3464 includes a voltage regulator, which is used to supply power for internal circuits operating in a wide input voltage range (12~80V), which simplifies the design of driver stages for different power supply voltages. The thermal protection feature is designed to reduce the average LED current under high ambient temperature to extend the life of the LED.
LM3464 has a fault handling circuit, which can avoid system faults caused by accidental short-circuit or open-circuit of the LED string. Two or more LM3464 can be connected in parallel to increase the number of output channels, thus realizing flexible system architecture design.
This evaluation board demonstrates the system efficiency and LED current adjustment accuracy of the LM3464 LED driver. Its typical application circuit is a 50W LED lighting system.
Figure 3 LM3464 4-channel LED driver evaluation board PCB component layout
Main features of LM3464 4-channel LED driver evaluation board
• Input voltage range: 12~80V
• LED turn-on voltage: 48V
• LED current of each channel: 350mA
• Thermal protection dimming frequency: 2kHz
Because the LED turn-on voltage of the LM3464 evaluation board is designed to be 48V, it is recommended to set the power supply voltage of the evaluation board below 60V to avoid high power consumption on the MOSFET of the low-side current regulator when the system is started. In order to drive different numbers of LEDs, the starting voltage needs to be adjusted by modifying the values of the resistors RFB1 and RFB2.
Figure 4 LM3464 4-channel LED driver evaluation board outline drawing
Other features of LM3464 4-channel LED driver evaluation board
• Dynamic headroom control (DHC)
• Thermal protection control
• High-speed PWM dimming
• Minimum brightness limit, thermal protection control can be achieved
• Cascade operation can realize output channel expansion
• Vin undervoltage lockout
• Fault protection and indication
• Programmable starting voltage
• Thermal shutdown