LT8653S is a dual channel, 2 A, synchronous buckstore, 2 A, synchronous buck regulator. Based on the Silent Switcher® 2 technology, LT8653S can be efficiently operated at high frequencies, and has excellent EMI performance, which can meet the demanding requirements of automotive, industrial, calculation and communication environments.
LT8653S integrates two independent regulator channels into a heat dissipation enhancement 3mm × 4 mm package. Each channel can also provide 2 A continuous output current, which can provide up to 3A current in the pulse load application. LT8653S supports burst mode®, only 6.2μA static current when both outputs are in a regulated state, which is a key feature of the battery power supply system.
LT8653s also provides forced continuous mode and extension (SSFM) operations. The SSFM mode reduces the peak radiation near the fundamental operating frequency by diffusing energy into a wider spectral range.
LT8653s provides external compensation options that can be used to optimize transient responses; or simply start, internal compensation can also be used. Fixed output options are also available, and the two output voltages can produce 5V, 3.3V and 1.8V output without using external feedback resistors.
Dual-channel 2A regulator with low EMI, high efficiency
Figure 1 shows the use of LT8653S with low EMI and high efficiency dual-channel output bucking regulator applications. The input voltage ranges from 5.8V to 42V and outputs 5V / 2A and 3.3V / 2A. The switching frequency is set to 2MHz. The internal regulator is powered by a 3.3V output to reduce power consumption. Enable burst mode (SYNC / MODE to GND) Optimize the efficiency of light load.
Figure 1. High-efficiency and low EMI wide input range, dual channel, 2A bucking regulator.
Figure 2 shows the radiation EMI of Figure 1, which conforms to strict automotive CISPR 255 radiation EMI specifications. When the LT8653S switching frequency is 2 MHz, the peak efficiency of the regulator at 12V input and 5V output reaches 94.8%, while the efficiency is 92.1% when the 24V input and 5V output.
Figure 2. Figure 1 CISPR 25 electromagnetic radiation harassment
Internal or external loop compensation
To minimize the number of components, the LT8653S has built-in internal loop compensation functionality for most systems. For design, external compensation can be used to minimize output voltage offset and transient response time. Figure 3 shows a dual output regulator aimed at optimizing transient response.
Figure 4 shows the 5V output (Vout1) in response to 0A to 2A load steps. In this case, the VOUT deviation is less than 80mV. This rapid transient response is combined with the high initial accuracy of LT8653S to meet the harsh VOUT fault tolerance requirements.
Figure 3.5V / 2A and 3.3V / 2A output, very fast load transient response.
Figure 4. A 0A to 2A load transient response of the circuit 5V rail in Figure 3.
Fixed output voltage option
In order to further reduce the number of components, the pins D0 and D1 of the LT8653S can be utilized to select different fixed output voltages, so that there is no need to use an external resistor to set the LT8653S output voltage. Depending on the selected D0 and D1 pin combinations, the internal feedback resistor divider can be enabled, and the FB pin can be connected directly to the VOUT to adjust 5V, 3.3V or 1.8V output. Since the external resistance network is not required, the overall solution size is small.
The total resistance of the internal feedback resistor divider is 12mΩ, so the no-load static current is low below the conventional static current using an external resistor divider circuit. The adjustment effect of the internal feedback resistor divider is better than that of the outer pressure, and the resistance error of the outer divider usually affects accuracy. Figure 5 shows a dual output regulator optimized for fewer devices - simply sets D0 and D1 pin to set up 5 V and 3.3 V output.
Figure 5. Quantity, dual channel, 2A buck regulator solution.
in conclusion
With Silent Switcher 2 technology, LT8653s can be run under high frequency while providing high efficiency and low EMI radiation. The LT8653S provides a wide input voltage range, low static current, and integrates two 2A regulator channels in a small 4mm × 3 mm package, thereby reducing the number of devices and the size of the solution. The LT8653S size is small and the number of external devices is small, and flexible design can be achieved for various applications.
Reprinted from electronic technology applications.
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