DH321 Datasheet PDF – Green Mode Fairchild Power Switch

Part Number: DH321

Function: Green Mode Fairchild Power Switch (FPS)

Package: DIP, SO 8 Pin Type

Manufacturer: Fairchild Semiconductor

DH321 fairchild switch


The DH321, FSDx321(x stands for H, L) are integrated Pulse Width Modulators (PWM) and Sense FETs specifically designed for high performance offline Switch Mode Power Supplies (SMPS) with minimal external components.


DH321 pinouts


• Internal Avalanche Rugged Sense FET
• Consumes only 0.65W at 240VAC & 0.3W load with Advanced Burst-Mode Operation
• Frequency Modulation for low EMI
• Precision Fixed Operating Frequency
• Internal Start-up Circuit
• Pulse by Pulse Current Limiting
• Abnormal Over Current Protection
• Over Voltage Protection
• Over Load Protection
• Internal Thermal Shutdown Function
• Auto-Restart Mode
• Under Voltage Lockout
• Low Operating Current (max 3mA)
• Adjustable Peak Current Limit
• Built-in Soft Start



DH321 Ordering Information

Both devices are integrated high voltage power switching regulators which combine an avalanche rugged Sense FET with a current mode PWM control block. The integrated PWM controller features include: a fixed oscillator with frequency modulation for reduced EMI, Under Voltage Lock Out (UVLO) protection, Leading Edge Blanking (LEB), optimized gate turn-on/turn-off driver, Thermal Shut Down (TSD) protection, Abnormal Over Current Protection (AOCP) and temperature compensated precision current sources for loop compensation and fault protection circuitry.


Block Diagram

DH321 Datasheet

DH321 Datasheet PDF Download

DH321 pdf

Other data sheets are available within the file: DH-321, DL321, FSDH321, FSDH321L, FSDL321

FAN7601 Datasheet – Green Current Mode PWM Controller

Part Number: FAN7601

Function: Green Current Mode PWM Controller

Package: DIP, SOP 8 Pin Type

Manufacturer: Fairchild Semiconductor


FAN7601 datasheet



The FAN7601 is a green programmable frequency current mode PWM controller. It is specially designed for the off-line adapter application and the auxiliary power supplies which require high efficiency at a light load and no load.

The internal high voltage start-up switch and the burst mode reduce the power loss. The FAN7601 includes some protections such as latch protection and over voltage protection. The latch protection can be used for over voltage protection and/or thermal protection and so on. And the soft start prevents the output voltage over shoot at start up.

Image and pinouts :

FAN7601 Block Diagram


1. Green Current Mode PWM Control

2. Low Operating Current: Max 4mA

3. Burst Mode Operation

4. Internal High Voltage Start-up Switch

5. Under Voltage Lockout (UVLO): 12V/8V

6. Latch Protection & Soft Start Function

7. Over Voltage Protection: 19V

8. Operating Frequency up to 300kHz

9. Max Duty Cycle: 95%

Typical Applications:

1. Off-Line Adapter Applications

2. Auxiliary Power Supplies

FAN7601 Datasheet

FAN7601 pdf

Other data sheets are available within the file:  FAN7601B, FAN7601BG, FAN7601BM ,FAN7601BMX

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