Optimizing your system

AN1818

5/6

The following table summarizes the parameters for each of the above systems:

We can see from the above comparison that by using the TSM1012 and a low-consumption optocoupler,

an economy of nearly 80% in power consumption can be obtained relative to the “typical” CC-CV

secondary side solution. And most importantly, it is possible with this advanced system to descend to only

104mW in no-load conditions.

However, we can also see that only improving the optocoupler and retaining a standard secondary-side

device (such as the TSM103) does not significantly improve the overall power consumption.

System A

“Typical

Configuration”

System B

“Optimized

Configuration”

System C

“Highly-Optimized

Configuration”

Secondary-side IC

TSM103

TSM1011

TSM1012

2.5V (externally polarized)

self-polarizing

self-polarizing

2.5k

Ω

none

none

7mA

none

none

1.5mA

1mA

0.1mA

1mA

1mA

1mA

9.5mA

2mA

1.1mA

no-load condition

20V

20V

20V

190mW

40mW

22mW

380mW

80mW

44mW

Primaryfunction power

dissipation

80mW

80mW

80mW

Total Power Consumption

460mW

160mW

124mW

Target consumption window

<500mW

<200mW

<150mW

Using a low-power optocoupler:

0.5mA

0.5mA

0.5mA

9mA

1.5mA

0.6

180mW

30mW

12mW

360mW

60mW

24mW

Primaryfunction power

dissipation

80mW

80mW

80mW

Total Power Consumption

440mW

140mW

104mW

Target consumption window

<500mW

<150mW

~100mW