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Author ：Iflowpower – Portable Power Station Supplier
DC / DC converters for automotive applications must work in extreme environments, input transients may exceed 5 times the nominal battery voltage, and last hundreds of milliseconds, while the temperature in the hood may rise sharply to far exceeding typical commercial use Level IC can withstand. In this harsh environment, space is shortage, so even more powerful devices must perform multiple functions. LT3694 / LT3694-1 adopts a compact 4mmx5mmqfn package or heat-resistant TSSOP package, and 2.
6A switch regulator and two low pressure difference linear regulators can meet these harsh requirements. The switching regulator only has a single inductor, with an internal power switch, a week-round period limit stream, and tracking / soft start control function. Each LDO only has an external NPN path transistor, and it is folded back current limit and tracking / soft start control capabilities.
When Vin exceeds 38V, the internal output detector turns off the switching regulator, thereby protecting the switch and Schottky rectifier. This allows the VIN pin of the device to withstand the transients of up to 70V without damaging the device itself or rectifier. Switch regulators of 4V to 36V LT3694 / LT3694-1 include a 36V single-chip switching regulator that supplies up to 2.
6A output current from a low to 4V input voltage. The output voltage can be set to be the same as the 0.75V feedback reference.
This regulator uses current mode, constant frequency architecture, which maintains a simple loop compensation. External compensation allows custom loop bandwidth, transient response, phase margin. Two low pressure difference linear regulators LT3694 / LT3694-1 include two LDO linear regulators, which use an external NPN path transistor to supply up to 0.
5A output current. The base driving can supply up to 10 mA of base current to the passage transistor, and is currently limited. LDO is internal compensation, which is stable with 2.
2F or greater output capacitance. LDO and switch regulator use the same 0.75V baseline.
If the BIAS pin is at least 0.9V higher than the DRIVE pin voltage, then the LDO takes the drive current from the BIAS pin, otherwise the LDO absorbs the drive current from VIN. This reduces the power consumption of LDO, especially when VIN is relatively high.
By monitoring the detection resistance on the NPN path transistor collecting electrode, the LDO realizes the re-return current limit. The initial threshold is set to 60mV, but with the VFB falls, it is folded until VFB = 0, the threshold is 26mV. 0.
1ωThe detection resistor sets the operating current limit to 600 mA, but the short-circuit current limit is reduced to 260 mA. This reduces the power consumption of the passage transistor when the short circuit is output. Figure 1: LT3694 / LT3694-1 For a wide input range, 3 output applications by pulling the FB pin above 1.
25V at a current of at least 30A, can turn off the LDO. If you want to perform independent control of LDO, you can pull down its TRK / SS pin low, forget each LDO output equal to 0V. If you want to track or soft start, use a tracking or a soft boot circuit described below.
If you don't track and start, then 1KωThe standard CMOS output (1.8V to 5V) of the series resistor can be done well.
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