The TL284xB and TL384xB series of control integrated circuits provide the features that are necessary to implement off-line or dc-to-dc fixed-frequency current-mode control schemes, with a minimum number of external components. Internally implemented circuits include an undervoltage lockout (UVLO) and a precision reference that is trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator that also provides current-limit control, and a totem-pole output stage designed to source or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the off state.

The TL284xB and TL384xB series are pin compatible with the standard TL284x and TL384x with the following improvements. The start-up current is specified to be 0.5 mA (max), while the oscillator discharge current is trimmed to 8.3 mA (typ). In addition, during undervoltage lockout conditions, the output has a maximum saturation voltage of 1.2 V while sinking 10 mA (V_CC = 5 V).

Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges. Typical UVLO thresholds of 16 V (on) and 10 V (off) on the TLx842B and TLx844B devices make them ideally suited to off-line applications. The corresponding typical thresholds for the TLx843B and TLx845B devices are 8.4 V (on) and 7.6 V (off). The TLx842B and TLx843B devices can operate to duty cycles approaching 100%. A duty-cycle range of 0% to 50% is obtained by the TLx844B and TLx845B by the addition of an internal toggle flip-flop, which blanks the output off every other clock cycle.The TL284xB-series devices are characterized for operation from -40°C to 85°C. The TL384xB-series devices are characterized for operation from 0°C to 70°C.

• Low Start-Up Current (<0.5 mA)
• Trimmed Oscillator Discharge Current
• Current Mode Operation to 500 kHz
• Automatic Feed-Forward Compensation
• Latching PWM for Cycle-by-Cycle Current Limiting
• Internally Trimmed Reference With Undervoltage Lockout
• High-Current Totem-Pole Output Undervoltage Lockout With Hysteresis
• Double-Pulse Suppression

• Topology
• Flyback, Boost,
• Duty cycle (Max) (%)
• 100
• Supply voltage (Max) (V)
• 30
• UVLO thresholds on/off (V)
• 16/10
• Features
• Adjustable Switching Frequency, Error Amplifier, Multi-topology
• Operating temperature range (C)
• -40 to 85
• Rating
• Catalog
• Frequency (Max) (kHz)
• 500
• Gate drive (Typ) (A)
• 1

TL2842B的完整型号有：TL2842BD、TL2842BD-8、TL2842BDR、TL2842BDR-8、TL2842BP，以下是这些产品的关键参数及官网采购报价：

TL2842BD，工作温度：-40 to 85，封装：SOIC (D)-14，包装数量MPQ：50个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网TL2842BD的批量USD价格：.384（1000+）

TL2842BD-8，工作温度：-40 to 85，封装：SOIC (D)-8，包装数量MPQ：75个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网TL2842BD-8的批量USD价格：.384（1000+）

TL2842BDR，工作温度：-40 to 85，封装：SOIC (D)-14，包装数量MPQ：2500个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网TL2842BDR的批量USD价格：.209（1000+）

TL2842BDR-8，工作温度：-40 to 85，封装：SOIC (D)-8，包装数量MPQ：2500个，MSL 等级/回流焊峰值温度：Level-1-260C-UNLIM，引脚镀层/焊球材料：NIPDAU，TI官网TL2842BDR-8的批量USD价格：.16（1000+）

TL2842BP，工作温度：-40 to 85，封装：PDIP (P)-8，包装数量MPQ：50个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：NIPDAU，TI官网TL2842BP的批量USD价格：.24（1000+）

PMP22899 — 24-W, 120-VAC to 24-VDC buck converter reference design

该参考设计使用 TL2842B 作为高侧降压转换器，将 120Vac 输入转换为 24Vdc 输出，能够承受 1A 的负载。在满载时，该参考设计可实现低峰峰值输出纹波以及超过 88% 的效率。该参考设计采用 2 层 PCB 和单面组装方式构建而成。