汽车中的电源系统有限且棘手。它之所以受到限制，是因为其主要来源是一个定期充电的单个12V电池。最重要的是，每天添加到汽车的电气和电子设备的量增加。新的负载包括扩展的信息娱乐系统，高级驾驶员辅助系统（ADA）和更复杂的LED照明。其他减少排放的系统也包括在内。但这不是全部。除非采取缓解措施，否则新的电子添加增加了车辆中电磁干扰水平（EMI）水平。
As it turns out, there are solutions for all of these design challenges, if you look in the right place. For example, Texas Instruments (TI) offers an array of devices that can accelerate and simplify designs.
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远程用品的LDO
Virtually all new electronic systems in vehicles require a constant stable dc supply voltage. And those sources need to be protected against shorts, opens, overvoltage conditions, and transients. The 12-V battery supply varies widely with constantly changing load conditions and ambient variations in a harsh environment.
结果，负载的电压调节至关重要，该法规不得导致车辆中的EMI/EMC问题。这就是为什么低防流（LDO）调节器是大多数汽车负载的选择 - 它们是有效的，并且没有产生切换噪声。
这infotainment and ADAS equipment often requires a remote or “phantom” dc supply. Power is typically delivered over a signal-carrying coax cable that’s subject to shorts, opens, environment degradation, and other maladies. Examples of remote loads include radio/GPS antennas with internal LNAs, backup cameras, and microphones with integral preamp. LDOs for these remote loads are ideal, but protection must be provided.
1.显示的是用于严重汽车应用的TPS7B770X-Q1 LDO的功能框图。DC在OUT1/OUT2处的直流输出通过也带有天线信号的同轴电缆向负载提供。（由德州仪器提供）
一种解决方案是像TI TPS7B7702-Q1这样的芯片，一个带有电流感的双通道天线LDO（图。1）。It can handle a wide range of input voltages from 4.5 to 40 V with load dump protection. The output voltage is adjustable from 1.5 to 20 V with a current capability up to 300 mA per channel. A notable feature is the current-sense capability that’s adjustable with an external resistor. The current-sense outputs may be multiplexed between channels and devices to minimize the need for multiple ADCs. The device is usually controlled by a companion MCU.
TI还提供了具有数字诊断和集成保护的四通道天线LDO参考设计。指定的TIDA-01569, this reference design demonstrates an approach for powering remote, off-board loads, often over coaxial cables（图2）。
2. TIDA-01569参考设计使用TPS7B7702-Q1 LDO实现了一个通用应用程序，显示了两个涵盖四个负载的两道通道设备。注意将感觉线对ADC和每个设备的MCU控制的多路复用。（由德州仪器提供）
This design offers protection against a variety of faults to which off-board cabling is susceptible, along with digital diagnostics. The I2C and fault flag protect against and diagnose reverse polarity, reverse current, short-to-battery, short-to-ground, and thermal shutdown. The integrated reverse-current protection doesn’t require an external diode at the output of the device, which saves cost and avoids increasing the dropout voltage.
增强前转换器最小化电池电压滴
另一个常见的汽车电源问题是severe drop in battery voltage that occurs during some operations in the vehicle。For example, there’s a serious drop when the engine is starting.
Many vehicles today feature a start-stop system that turns off the engine while stopped and idling. This helps reduce emissions and improve gas mileage. When the vehicle restarts, the battery voltage drops significantly. To help maintain voltages to critical loads during restarting, most vehicles now use pre-boost converters.
这basic requirements of a pre-boost converter are:
- Ability to tolerate an input voltage range between 2.5 and 40 V, 12 V typical.
- 输出电压能力在8.5至40 V之间。
- Output current in the 2- to 4-A range.
- 短唤醒延迟。
One device that more than meets the minimum requirements is the TI LM5150-Q1 boost controller. It can handle an input voltage of 1.5 to 42 V and consumes less than 15 µA of quiescent standby current (I问）。它提供了四个可选的输出电压，为6.8、7.5、8.5和10.5V。
这device is a switching converter whose switching frequency can be set to any value in the 220-kHz to 2.3-MHz range. A frequency of 2.2 MHz is common, as it helps minimize AM radio interference.
3.并非所有的增强前转换器都可以容纳汽车系统中发生的深电压下降和不足的（绿色曲线）。Ti LM5150-Q1基本上解决了此问题（红色曲线）。（由德州仪器提供）
One of the problems that appears with some pre-boost converters isundershoot when the battery voltage drops。电池电压的强烈多压降低是由于增强前转换器的迅速唤醒而发生的。图3显示一个示例。在输出以其集合输出稳定之前，这种不足可以持续数百微秒。
快速的唤醒时间基本上消除了此问题，并增加了转换器错误散布器参考电压。Ti LM5150-Q1解决了这个问题。
A Reference Design for Automotive Start-Stop Problem
这TIDT001参考设计为宽阔的电压下降提供了一个组合解决方案，可能会对苛刻的汽车信息娱乐，工具簇和ADAS设备产生负面影响。它具有低i问LM5150-Q1 boost controller and the LM5141-Q1 buck controller that offer features 2.2-MHz switching, few external components, small solution size, and fast dynamic response even under severe start-stop cranking scenarios.
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