一,产品概述(General Description)         
      The JTM3109 is a 180 KHz fixed frequency PWM buck (step-down) DC/DC converter,capable of driving a 2.5A load with high efficiency, low ripple and excellent line and load regulation. Requiring a minimum number of external components, the regulator is simple to use and include internal
frequency  compensation and  a fixed-frequency oscillator.
     The PWM control circuit is able to adjust the duty ratio linearly from 0 to 100%. An over current protection function is built inside. When short protection function happens, the operation frequency will be reduced from 180KHz to 48KHz. An internal compensation block is built in to minimize external component count

二.产品特点(Features)

 Wide 8V to 36V Input Voltage Range
Output Adjustable from 1.25V to 32V
Maximum Duty Cycle 100%
Minimum Drop Out 0.3V
Fixed 180KHz Switching Frequency
Maximum 3A Switching Current
Internal Optimize Power MOSFET
High efficiency
Excellent line and load regulation
With output constant current loop
Built in thermal shutdown function
Built in current limit function
Built in output short protection function
Available in SOP8L package


三,应用范围 (Applications)
Battery Charger
LCD Monitor and LCD TV
Portable instrument power supply
Telecom / Networking Equipment



四,产品封装图 (Package)

Pin Number	Pin Name	Description
1	FB	Feedback Pin (FB). Through an external resistor divider network, FB senses the output voltage and regulates it. The feedback threshold voltage is 1.25V.
2	OCSET	Output Constant Current Set Pin;
3	VC	Internal Voltage Regulator Bypass Capacity. In typical system application, The VC pin connect a 1uf capacity to VIN.
4	VIN	Supply Voltage Input Pin. HM3109 operates from a 8V to 36V DC voltage. Bypass Vin to GND with a suitably large capacitor to eliminate noise on the input.
5,6	SW	Power Switch Output Pin (SW). SW is the switch node that supplies power to the output.
7,8	GND	Ground Pin. Care must be taken in layout. This pin should be placed outside of the Schottky Diode to output capacitor ground path to prevent switching current spikes from inducing voltage noise into JTM3109.

五,电路原理图


六, 产品PCB


PCB 布局指南
1. VIN、GND、SW、VOUT 等功率线，粗、短、直；
2. FB 走线远离电感与肖特基等开关信号地方，建议使用地线包围；
3. 输入电容靠近芯片 VIN 与 GND 引脚。

 
七.产品BOM  

序号	数量	参考位号	说明	生产商型号	生产商
1	3	C1,C2,CC	1uF,50V,Ceramic,X7R,0805	C2012X7R1H105K	TDK
2	1	C3	33pF,50V,Ceramic,CH,0603	C1608CH1H330J	TDK
3	2	CINA,CINB	47uF,50V,Electrolytic,(6.3*11)	YXA-50V-47uF	Rubycon
4	1	COUT	220uF,16V,Electrolytic,(6.3*11)	YXA-16V-220uF	Rubycon
5	1	D1	40V,5A,SMC,Schottky Barrier Rectifier	B540C	DIODES
6	1	DZ	6.2V,500mW,ZENER,MINI MELF	ZMM55C6V2	ICM
7	1	FUSE	2A,63V,High Inrush,1206	F1206HI2000V063T	AEM
8	1	L1	47uH,3A,(10*4)
9	1	L2	100uH,2A(8*10)
10	1	LED	Blue,0805,SMD
11	1	R1	3.3KΩ,1%,1/16W,Thick Film,0603	RC0603XR-073301	Yageo
12	1	R2	10KΩ,1%,1/16W,Thick Film,0603	RC0603XR-071002	Yageo
13	1	R3	1KΩ,1%,1/16W,Thick Film,0603	RC0603XR-071001	Yageo
14	1	R4	33Ω,1%,1/4W,Thick Film,1206	RC1206XR-070330	Yageo
15	1	R5	75KΩ,1%,1/16W,Thick Film,0603	RC0603XR-077502	Yageo
16	2	R6,R8	49.9KΩ,1%,1/16W,Thick Film,0603	RC0603XR-074992	Yageo
17	1	R7	43.2KΩ,1%,1/16W,Thick Film,0603	RC0603XR-074322	Yageo
18	1	RCS	14KΩ,1%,1/16W,Thick Film,0603	RC0603XR-071402	Yageo
19	1	U1	36V,3A,BUCK,DC-DC Converter,SOP-8L	JTM3109
20	1	USB	DIP

八.产品PDF文档 

JTM3109

九,功能概述
产品JTM3109 制作的演示板，用于 DC8V~36V 输入，输出电压 5V，输出电流 2.1A 的车充应用演
示，最高转换效率可以达到 93%。
JTM3109 是开关降压型 DC-DC 转换芯片；固定开关频率 180KHz，可减小外部元器件尺寸，方便 EMC 设计。芯片
具有出色的线性调整率与负载调整率，输出电压支持 1.25V~32V 间任意调节。芯片内部集成过流保护、过温保护、短
路保护等可靠性模块。
JTM3109 为标准 SOP-8L 封装，集成度高，外围器件少，应用灵活

十,相关产品

DC-DC降压IC
型号	输入耐压	输出电压	输出电流	反馈电压	工作频率	效率	静态	待机电流	封装	直接替换
							工作电流
LM2596	45V	5.0V/可调输出	3A	1.23V	150K	90%	10mA	80uA	TO-263-5L	LM2596/AP1501
		/3.3/12V				(Max)			TO-220-5L
LM2576	45V	5.0V/可调输出	3A	1.23V	50K	90%	10mA	80uA	TO-263-5L	LM2576
		/3.3/12V				(Max)			TO-220-5L
JTM1507	45V	5.0V/可调输出	3A	1.23V	380K	73%	2mA	0.2uA	TO-252-5L	AP1507
MP1410	27V	可调输出	2A	1.22V	420K	95%	1mA	25uA	SOP8	MP1410/ACT4060
										MP9141/RT826
										AP1534
JTM1509	45V	5.0V/可调输出	2A	1.23V	150K	82%	2mA	80uA	SOP8	AP1509
		3.3V/12V
JTM1513	20V	可调输出	2A	0.8V	150K	89%	2mA	1uA	SOP-8	AP1513
JTM1530	20V	可调输出	3A	0.8V	380K	88%	3mA	1uA	SOP-8	AP1510
JTM1583	28V	可调输出	3A	1.22V	380K	89%	3mA	1uA	SOP-8	MP1583
JTM3111	42V	可调输出	3A	0.8V	50-500K	91%	3mA	150uA	ESOP8	AX3111
JTM3112	40V	可调输出/	2A	1.18V	110K	93%	10mA	2mA	SOP8
		带CC/CV模式
JTM3113B	40V	可调输出/	2.5A	1.0V	250K	91%	10mA	2mA	ESOP8
		带CC/CV模式
JTM3101	45V	可调输出/	2A	1.235V	150K	83%	2.0mA		ESOP8
		带CC模式
JTM3102	45V	可调输出/	3A	1.25V	150K	89%	2.0mA		ESOP8
		带CC模式
JTM3109	40V	可调输出/	3A	1.25V	180K	89%	2.1mA		SOP8
		带CC/CV模式
JTM3108	40V	可调输出/	3.5A	1.25V	180K	87%	2.1mA		ESOP8
		带CC/CV模式
JTM4523	40V	可调输出/	3A	0.8V	225K	92%	2.84mA	75uA	ESOP8	AC4523/F5335
		带CC/CV模式
JTM3501	50V	5V固定输出	1.8A		150K	90%	4.7mA		SOP-8
JTM3511	50V	5V固定输出	2.1A		150K	90%	4.7mA		SOP-8
JTM3512	50V	5V固定输出	2.4A		150K	89%	4.7mA		SOP-8
JTM3513	50V	5V固定输出	3.2A		150K	87%	4.7mA		TO-252-5L