LT8391D是一款同步4开关降压-升压LED控制器，可根据高于、低于或等于输出电压的输入电压调节LED电流。专有的峰值-降压/峰值-升压电流模式控制方案支持可调节的150kHz至650kHz固定频率运行方式，或支持可降低EMI的内部±15%三角扩频运行方式。LT8391D具有4V至60V输入和0V至60V输出，并支持在操作区域之间的无缝低噪声转换，非常适合汽车、工业和电池供电系统中LED驱动器应用。

LT8391D通过可选低端NMOS开关提供LED电流PWM调光。CTRL引脚提供灵活的20:1模拟调光，在100mV满量程下具有±4%的LED电流精度。提供的故障保护机制可以检测LED开路或短路情况，在此期间LT8391D将处于重试、闩锁或保持运行状态。

应用

• 汽车前照灯/行车灯
• 高频LED照明

• 4开关单电感器架构允许VIN高于、低于或等于VOUT
• 同步开关：效率高达98%
• 专有峰值-降压峰值-升压电流模式
• 宽VIN范围：4V至60V
• 宽VOUT范围：0V至60V
• ±4% LED电流精度

• 在降压或升压模式下没有顶部MOSFET刷新噪声
• 可调频率：150kHz至650kHz
• 无闪烁扩频，帮助实现低EMI
• 开路和短路LED保护，并提供故障报告
• 通过AEC-Q100汽车应用认证

LT8391DJUFDM#WPBF，封装：28-Lead QFN (4mm x 5mm, Plastic Side Wettable)，包装形式及数量：管装，73，工作温度：-40 to 150C，AD官网报价：3.6（100-499个）；3.03（1000+个）

LT8391DJUFDM#WTRPBF，封装：28-Lead QFN (4mm x 5mm, Plastic Side Wettable)，包装形式及数量：卷带，2500，工作温度：-40 to 150C，AD官网报价：3.6（100-499个）；3.03（1000+个）

EVAL-LT8391D-AZ：LT8391D | Synchronous 4-Switch Buck-Boost LED Driver 6V to 45V Input, Up to 50V LED

Evaluation circuit EVAL-LT8391D-AZ is a 4-switch synchronous buck-boost LED driver featuring the LT8391D. It drives a single string of LEDs at up to 1.5A and up to 50V when VIN is between 6V and 45V. EVAL-LT8391D-AZ runs at 400kHz switching frequency and efficiency can exceed 97%. It comes with low EMI features including optimized layout, spread spectrum frequency modulation (SSFM) and input EMI filter. SSFM can be turned on or off with a simple jumper.

The LT8391D 4-swich buck-boost controller is the new member of the LT8391 family (see Table 1 in the user guide). It has an input voltage range of 4V to 60V and output voltage range of 0V to 60V. It has input under voltage lockout (UVLO) which can also be used to enable or disable the controller. On the output side, it is protected against both open and short LED conditions.

The LT8391D allows adjustable switching frequency between 150kHz and 650kHz. It can be PWM dimmed with an external PWM signal. When run with PWM dimming and either fixed switching frequency or SSFM, the internal oscillator aligns itself with the PWM signal for flicker-free operation. On EVAL-LT8391D-AZ, the PWM pin is pulled up to INTVCC through a 100k resistor. Therefore, the LED string is 100% ON when there is no external PWM signal. It can also be analog dimmed with a control voltage on its control pin (CTRL).

EVAL-LT8391D-AZ features MOSFETs that complement the 5V gate drive of the LT8391D to achieve high efficiency. All MOSFETs used on the 4-switch topology are rated at 60V and AEC-Q101 qualified. Ceramic capacitors are used at both input and output side due to their small size and high ripple current capability. In addition to ceramic capacitors, there is one aluminum electrolytic capacitor at the input side to mitigate the effects of the input and output transients.

Sense resistor for LED current can be placed either on high side (LED+) or low side (GND). With high side sense resistor, LED– is directly connected to GND. This gives the option to run only one wire (LED+) to LED string and use chassis ground as return path in automotive or similar applications. LT8391D guarantees ±4% current regulation accuracy with high side sense resistor. Low side sense resistor gives the most accurate LED current regulation. EVAL-LT8391D-AZ implemented both high side and low side sense resistors, with high side sense resistor as default and low side sense resistor as optional.

The LT8391D data sheet gives a complete description of the part, operation and applications information. The data sheet must be read in conjunction with the user guide for evaluation circuit EVAL-LT8391D-AZ. The LT8391DJUFDM is assembled in a 28-lead plastic 4mm × 5mm QFN package with a thermally enhanced GND pad. Proper board layout is essential for maximum thermal performance and EMI performance. Please see the evaluation kit design files for details, including top layer layout, inner traces and grounding.

Refer to the Emission Results section of the user guide for the excellent EMI performance of this evaluation board.