TL3843 Current-Mode PWM Controller

TL3843是固定频率电流模式PWM控制器IC。TL3843 IC提供了实现离线或DC-DC固定频率电流模式控制方案所必需的功能，并具有最少数量的外部组件。

Note: This IC also comes in the 14-Pin package. This article covers only the 8-Pin version of the IC.

Pin Description TL3843:

Pin Number	Pin Name	Description
1	COMP (Comparator)	It is an output pin that outputs low impedance 1MHz signal based on the difference between the set and current-voltage. It is normally connected to the voltage feedback pin of the IC through a resistor and capacitor.
2	VFB（电压反馈）	It is an input to the error amplifier inside the IC. The difference in voltage level is supplied to this pin.
3	Current Sense	分流电阻用于通过电路监视电流，并且在其上方的电压作为对电流sense Pin的反馈提供。
4	RT/CT(Timing Resistor/ Timing Capacitor)	The IC has an internal oscillator which can be set using an external resistor and capacitor connected to this pin.
5	地面	Connected to the ground of the circuit.
6	Output	This pin outputs the PWM signal based on the feedback provided and we can use this to switch the power electronic device.
7	Vcc	IC的电源电压（名义11V）
8	VREF	基于产生PWM信号的参考电压。

TL3843Specifications & Features

• Current-Mode PWM controller
• Supply Voltage: 7.6V to 30V
• Output Voltage: 0V to 30V
• Output pin current: 200 mA
• Switching Frequency: 500 kHz
• Duty Cycle - Max: 100 %
• Optimized for Off-line and DC-to-DC Converters
• 高电流图腾孔输出
• Fall Time: 50ns
• 上升时间：50NS

Note:Complete Technical Details can be found at the TL3843 datasheet given at the end of this page.

当量/苏bstitute forTL3843:UC3843, TL3842

Alternatives PWM controller IC:UC2842,SG2524

Where to use the TL3843 PWM Controller IC:

The UC3844 current Mode PWM Controller can be used for DC to DC conversion regardless of buck or boost topology. TL3843 can be used to provide a constant current by varying the output voltage to the load. This IC features a trimmed oscillator for precise duty cycle control, a temperature compensated reference, a high gain error amplifier, a current sensing comparator, and a high current totem pole output for driving a Power MOSFET.

So if you are looking for an IC to produce PWM signals for controlling a power switch based on the current flowing through the circuit, then this IC might be the right choice for you.

如何使用TL3843：

Using TL3843 in a circuit is very simple as it requires a minimum number of components. A sample application circuit from the TL3843 datasheet is shown below.

The input voltage to the VCC pin should be 7.6V to 30V. The VFB (Voltage feedback) pin acts as feedback based on which the PWM signal is controlled. A shunt resistor is used to monitor the change in current in the circuit and then this difference voltage across the shunt is provided to the feedback pin. VREF is used to provide charging current to the oscillator timing capacitor through the timing resistor. It is important for reference stability that VREF is bypassed to GROUND with a ceramic capacitor connected as close to the pin as possible.

Applications of TL3843:

• SMPS (Switch Mode Power Supplies) circuits
• DC-DC converter circuits
• 电子电源
• Battery drain circuit
• Load machines

2D-Model ofTL3843:

Dimensions for TL3843 IC is given below. These dimensions are for the 8-PinGDIPpackage. If you are using a different package IC, please refer to the TL3843 datasheet.