High Current DC-DC Converter – 12V/6A Output from 16V to 38V DC Input
The project presented here is a low quiescent current, synchronous buck converter featuring the LTC3807. This DC-DC converts a 16V to 38V input voltage to a 12V at 6A output. The main features of this board include an internal LDO for gate drive power from VIN or EXTVCC, RUN pins, a mode selector jumper CN1 that allows the converter to run in constant current mode (CCM), pulse-skipping or Burst Mode operation, and selectable current limit. Output is fixed and provides 12V DC but it supports an adjustable output voltage. Refer to the datasheet below to learn more about the adjustable output. The circuit has also soft-start and tracking. The wide input voltage range of 16V to 38V is suitable for automotive and distributed DC power systems where the low quiescent current is essential. The operating frequency is set to 120Khz using resistor R6. MOSFETs are mounted under the PCB for easy heatsink mounting, it is important to use a heatsink for a full current load.
Main Control Loop
The LTC3807 uses a constant frequency, current mode step-down architecture. During normal operation, the external top MOSFET is turned on when the clock for that channel sets the RS latch and is turned off when the main current comparator, ICMP, resets the RS latch. The peak inductor current at which ICMP trips and resets the latch is controlled by the voltage on the ITH pin, which is the output of the error amplifier, EA. The error amplifier compares the output voltage feedback signal at the VFB pin (which is generated with an external resistor divider connected across the output voltage, VOUT, to ground) to the internal 0.800V reference voltage. When the load current increases, it causes a slight decrease in VFB relative to the reference, which causes the EA to increase the ITH voltage until the average inductor current matches the new load current. After the top MOSFET is turned off each cycle, the bottom MOSFET is turned on until either the inductor current starts to reverse, as indicated by the current comparator IR, or the beginning of the next clock cycle.
Features
- Wide VIN Range: 16V to 38V (40V Abs Max)
- Output 12V DC Load Up to 6Amps
- Low Operating IQ: 50μA
- Output Voltage 12V (Adjustable Range: 0.8V ≤ VOUT ≤ 24V Read Note 2)
- Frequency 120khz
- Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode Operation at Light Load
- Over Current Limit
- Efficiency up to 95%
- Very Low Dropout Operation: 99% Duty Cycle
- Inbuilt Soft-Start
- Output Overvoltage Protection
- Low Shutdown IQ: 14μA
- Internal LDO Powers Gate Drive from VIN or EXTVCC
- No Current Foldback During Start-Up
- PCB Dimensions 71.44 x 41.75mm
- 4 x 3mm Mounting Holes
Share
The project presented here is a low quiescent current, synchronous buck converter featuring the LTC3807. This DC-DC converts a 16V to 38V input voltage to a 12V at 6A output. The main features of this board include an internal LDO for gate drive power from VIN or EXTVCC, RUN pins, a mode selector jumper CN1 that allows the converter to run in constant current mode (CCM), pulse-skipping or Burst Mode operation, and selectable current limit. Output is fixed and provides 12V DC but it supports an adjustable output voltage. Refer to the datasheet below to learn more about the adjustable output. The circuit has also soft-start and tracking. The wide input voltage range of 16V to 38V is suitable for automotive and distributed DC power systems where the low quiescent current is essential. The operating frequency is set to 120Khz using resistor R6. MOSFETs are mounted under the PCB for easy heatsink mounting, it is important to use a heatsink for a full current load.
Main Control Loop
The LTC3807 uses a constant frequency, current mode step-down architecture. During normal operation, the external top MOSFET is turned on when the clock for that channel sets the RS latch and is turned off when the main current comparator, ICMP, resets the RS latch. The peak inductor current at which ICMP trips and resets the latch is controlled by the voltage on the ITH pin, which is the output of the error amplifier, EA. The error amplifier compares the output voltage feedback signal at the VFB pin (which is generated with an external resistor divider connected across the output voltage, VOUT, to ground) to the internal 0.800V reference voltage. When the load current increases, it causes a slight decrease in VFB relative to the reference, which causes the EA to increase the ITH voltage until the average inductor current matches the new load current. After the top MOSFET is turned off each cycle, the bottom MOSFET is turned on until either the inductor current starts to reverse, as indicated by the current comparator IR, or the beginning of the next clock cycle.
Features
- Wide VIN Range: 16V to 38V (40V Abs Max)
- Output 12V DC Load Up to 6Amps
- Low Operating IQ: 50μA
- Output Voltage 12V (Adjustable Range: 0.8V ≤ VOUT ≤ 24V Read Note 2)
- Frequency 120khz
- Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode Operation at Light Load
- Over Current Limit
- Efficiency up to 95%
- Very Low Dropout Operation: 99% Duty Cycle
- Inbuilt Soft-Start
- Output Overvoltage Protection
- Low Shutdown IQ: 14μA
- Internal LDO Powers Gate Drive from VIN or EXTVCC
- No Current Foldback During Start-Up
- PCB Dimensions 71.44 x 41.75mm
- 4 x 3mm Mounting Holes
Dotfry has partnered with reputed logistic partners for our logistic services, to ensure that all our products reach you in the best of conditions with no damages. We ensure you that we use packaging materials of the best quality, which is sourced from reliable vendors, and ensure thorough testing of package worthiness before using them for shipping and delivery of our products.
Related Products
