* From page 10 of AN954:
Figure 10 shows a capacitive power supply with several UL considerations designed in. A fuse is added to protect the circuit during an over-current condition. Adding R2 in parallel with C1 creates a filter that will attenuate EMI from traveling back onto the line. A varistor, or MOV, provides transient protection.
Advantages of Capacitive Power Supply:
Significantly smaller than a transformer-based power supply.
More cost effective than a transformer-based or switcher-based power supply.
Power supply is more efficient than a resistive transformerless power supply.
Disadvantages of Capacitive Power Supply:
Not isolated from the AC line voltage which introduces safety issues.
Higher cost than a resistive power supply.
* Efficiency calculated as (4.1V x 9mA)/(120V x 16mA).
Manufacturer | Microchip Technology |
---|---|
Category | AC/DC and DC/DC Conversion |
Sub-Category | AC/DC SMPS - Single Output |
Eval Board |
Board not Stocked
|
AC Voltage |
115 V
|
Outputs and Type |
1 Non-Isolated
|
Voltage Out |
4.1 V
|
Current Out |
9 mA
|
Output Power |
37 mW
|
Features |
Soft Start
|
Efficiency @ Conditions |
>1%, 120V in, 4.1V @ 9 mA
|
No-load Input Power @ Voltage |
1.92 W @ 120 V
|
Switching Frequency | |
Internal Switch | |
Component Count + Extras |
8 + 0
|
Voltage In |
120 VAC
|
Design Author |
Microchip Technology
|
Application / Target Market |
Power: Auxiliary Power Supply
|
Main I.C. Base Part | |
Date Created By Author | |
Date Added To Library | 2011-10 |