Experimental results

AN2872

14/23

Doc ID 15305 Rev 1

Figure 7.

Output voltage ripple for different input voltages

4.2

Standby

The VIPer16 is designed to operate without any external power source. The device can be

supplied, thanks to its very low consumption, directly from an internal high voltage circuit

(see Section 6: References: 3). A major benefit of this feature is a reduction of the external

component count, as well as the possibility to generate output voltages that are below

voltage lockout. The buck converter based on the VIPer16 can directly generate, with

a simple inductor, 5 V (for example). On the other hand, as this method of self-supply is

based on the resistive principle, this method of supply increases power losses, which is

mainly visible in standby power losses. If low standby power losses is a priority, it is

used for feedback and consequently to reduce standby consumption.

Another aspect which significantly influences standby consumption are the balancing

resistors. The value of the balancing resistor was set to 1.5 M

Ω, respecting the fact that

there is no resolutely defined manufacturer of the capacitors, and consequently the worse

case is presented for calculation of the balancing resistors. The effect of these resistors on

standby consumption can be partly reduced (mainly for voltages below 400 VAC) using

Zener diodes instead of resistors (see Figure 8).