Highly recommended: Universal high-performance power supply solution that FPGA developers love to use
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Dual digitally adjustable analog loops and a digital interface for control and monitoring
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Wide input voltage range: 4.5V to 16V
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Wide output voltage range: 0.5V to 3.3V
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±0.5% Maximum DC Output Error Over Temperature
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±5% current readback accuracy
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Sub 1mΩ DCR Current Sensing
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Integrated input current sense amplifier
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400kHz PMBus-compatible I2C serial interface
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Supports remote sampling polling rate up to 125Hz
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An integrated 16-bit sigma-delta ADC
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Constant Frequency Current Mode Control
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With balanced current sharing capability, it can be used in parallel
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16mm×16mm×5.86mm CoP-BGA package
I2C-based PMBus interface and programmable loop compensation
The LTM4678 is part of ADI's Power System Management (PSM) µModule family and can be configured and monitored via a PMBus/SMBus/I2C digital interface. The PC-based LTpowerPlay® tool enables visual monitoring and control of supply voltage, current, power usage, sequencing, margining, and fault logging data. The LTM4678 is the first µModule regulator with programmable loop compensation (gm and RTH), which greatly reduces design time because dynamic performance tuning does not require repeated construction or modification of PCB boards.
CoP-BGA package for improved thermal performance, small size and high power density
The high power LTC4678 is implemented in a small 16mm x 16mm PCB footprint using a thermally enhanced component-on-package (CoP) BGA package. The inductor is stacked and acts as a heat sink to effectively reduce board temperature.
Easily scales to higher currents using current mode control
The LTM4678 uses peak current mode control to monitor and control current cycle by cycle, thereby achieving current sharing in multi-phase parallel applications.
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In high current applications, remote dual output sensing can compensate for voltage drops on the traces.
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±0.5% maximum DC output error over temperature provides additional regulation margin
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Direct input current sensing measures accurate input current and power
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A dedicated PGOOD pin signals the downstream system when the output voltage is within regulation.
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EXTVCC pin maximizes efficiency at high V IN
Dual output converter (1 V/25 A and 1.8 V/25 A)
Figure 1 shows a typical 5.75V to 16V input, dual output solution. The two channels of the LTM4678 operate with a relative phase shift of 180°, thus reducing input rms current ripple and capacitor size.
Figure 1. 1V/25A and 1.8V/25A outputs (with I2C serial control and monitoring interface)
As shown in Figure 2, in forced continuous current mode (CCM), the total solution efficiency is 85.8% (1.0V/25A output) and 90.4% (1.8V/25A).
Figure 2. Efficiency of two outputs.
Figure 3 shows the thermal performance of the LTM4678 operating at V IN = 12V, V OUT0 = 1.0V/25A, and V OUT1 = 1.8V/25A at 200 LFM. The hot spot (inductor on CH1) temperature rise is 63°C, while the ambient temperature is approximately 24°C.
Figure 3. Thermal performance of a dual-output converter.
Polyphase, single output high current (12V to 1V/250A)
The LTM4678 can be configured as a multiphase single output converter to create a higher current solution. Figure 4 shows a block diagram for connecting multiple LTM4678s. To increase the output current, simply add additional LTM4678s and connect their respective V IN , V OUT , V OSNS+ , V OSNS− , PGOODs, COMPa/b, RUN, FAULT, SYNC and GND pins together.
Figure 4. Block diagram showing the simplicity of multiphase operation.
Figure 5 shows the current provided by each phase when five LTM4678s are connected in parallel (10 phases). The maximum current difference between the 10 phases is 0.75A (3% based on 25A), representing balanced current sharing.
Figure 5. Current sharing between five LTM4678 devices (10 phases in parallel).
Figure 6 shows a thermal image of five LTM4678s in parallel at 220A output and 450LFM airflow. The maximum temperature difference between the five µModule regulators is 10°C. Figure 7 shows a complete schematic for an 8-phase solution.
Figure 6. Thermal performance of a multiphase converter.
Figure 7. 8-phase operation using four LTM4678s (generating 1V/200A output).
in conclusion
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