With the increasing popularity of modern car sales, the automotive industry's process development has also improved qualitatively, but the requirements for automotive power supply systems are increasingly responsible. Everyone knows that there is a special automotive voltage regulator in the power supply system of the car. Nowadays, with the improvement of the automobile manufacturing process, a better requirement is put forward for the applicable performance of the buck type used in the automotive power supply system.
The following is a description of Linear Technology's LTC7138, a step-down regulator for automotive environments. The LTC7138 is a 400mA step-down regulator that operates from an input voltage range of 4V to 140V, making it ideal for industrial, telecommunications, and Automotive and other applications that are often subjected to severe voltage transients. Since the regulator uses a hysteresis architecture, no external compensation is required. The output voltage can be set to 1.8V, 3.3V or 5.0V using the pin, or, if an external divider is used, the output can be adjusted from 0.8V to VIN. With an internal P-channel FET, 100% duty cycle operation is possible. The LTC7138 is packaged in a thermally enhanced high voltage (some pins are removed) MSOP package.
1. Simple 5V/400mA step-down with wide VIN range
Figure 1 shows a 5V step-down converter with a maximum input voltage of 140V and using only four external components. Set the output to 5V by connecting the VPRG1 pin to the SS pin and VPRG2 to ground. This device does not require any external compensation.
Figure 1: High Efficiency 5V, 400mA Step-Down Regulator
Figure 2: Efficiency of the regulator shown in Figure 1.
High efficiency is maintained over a wide load range, thanks in part to the LTC7138's Burst Mode? operation and 12μA unloaded IQ current. With a 12V input, the efficiency peaks up to 87% for a 10mA load and over 80% at a load as low as 0.4mA. This level of energy savings makes it ideal for battery-powered systems that are always on.
2. 24V/800mA step-down using two parallel LTC7138s
Figure 3 shows the situation where two LTC7138s are connected in parallel to provide a 24V/800mA output. Parallel operation is achieved by connecting the feedback comparator output pin (FBO) of the master to the VFB pin of the slave. In this setup, the slave will follow the master to enter and exit the burst cycle (see Figure 4). The output of the 24V buck converter is set with an external feedback divider. When using a 48V input, the regulator's full load efficiency is 93.6% (Figure 5).
Figure 3: High efficiency 24V, 800mA step-down with two parallel LTC7138s
Figure 4: 24V, 800mA Step-Down Converter Operating in Parallel (at VIN = 140V, IOUT = 600mA)
Figure 5: Efficiency of the regulator shown in Figure 3.
3, 32V/400mA surge suppressor
Figure 6 shows another application of the LTC7138. For 32V or lower inputs, the regulator operates in a dropout state where the internal power FET is continuously turned on. When the input exceeds 32V, the LTC7138 will perform a switch to maintain the output voltage in regulation, as shown in Figure 7. For further protection, overvoltage lockout can be achieved by connecting the OVLO pin to a voltage divider across the input supply. This circuit is suitable for protecting downstream converters or loads in industrial, automotive and avionics systems.
Figure 6: 32V, 400mA Surge Suppressor
Figure 7: The output of the surge suppressor (Figure 6) is clamped to 32V during a 127V input transient
More features: The LTC7138 offers features that make it suitable for a wide range of applications. This includes a RUN pin for external UVLO, an ILIM pin for current limit programming or setting the input side current limit, and a soft start function (internal or external).
Edit Comment: This article briefly introduces the LTC7138, a buck regulator for automotive environments. The LTC7138 implements a rugged solution with a low component count for wide input voltage applications. It features a 140V maximum rated input voltage, a thermally enhanced high voltage MSOP package, burst mode operation, low IQ current, pin adjustable output voltage, no external compensation, and operation at 100% duty cycle Features.
Digital display meter is the abbreviation of digital display instrument. LED and LCD are commonly used as display elements.
Digital display meter has the characteristics of visual intuition, convenient setting and high degree of intelligent control. In addition, with the rapid development of current sensing technology, the function of digital display instrument is becoming more and more powerful and the accuracy is constantly improving. Digital display instrument is replacing traditional mechanical instrument in a large number and has been widely used in all walks of life and daily life.
Digital Display Meter,Digital Display Intelligent Meter,Electrical Connection Digital Display Meter,Intelligent Digital Panel Instrument
Taizhou Jiabo Instrument Technology Co., Ltd. , https://www.taizhoujbcbyq.com